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rfRXD0420/0920
UHF ASK/FSK/FM Receiver
Features:
* Low cost single conversion superheterodyne receiver architecture * Compatible with rfPICTM and rfHCS series of RF transmitters * Easy interface to PICmicro(R) microcontroller (MCU) and KEELOQ(R) decoders * VCO phase locked to quartz crystal reference: - Narrow receiver bandwidth - Maximizes range and interference immunity * Selectable LNA gain control for improved dynamic range * Selectable IF bandwidth via external ceramic IF filter * Received Signal Strength Indicator (RSSI) for signal strength indication (FSK, FM) and ASK demodulation * FSK/FM quadrature (phase coincidence) detector demodulator * 32-Lead LQFP package
Pin Diagram:
LQFP
VDD LNAIN VSS LF ENRX VDD XTAL VSS 32 31 30 29 28 27 26 25 VSS LNAGAIN LNAOUT 1IFIN VSS 1IF+ 1IFVDD
1 2 3 4 5 6 7 8
rfRXD0420 RFRXD0920
24 23 22 21 20 19 18 17
DEMOUTDEMOUT+ VSS RSSI OPA+ OPAOPA VDD
16 15 14 13 12 11 10 9 DEMIN 2IFOUT VDD FBC2 FBC1 2IFIN VSS 1IFOUT
Applications:
* * * * * * * Wireless remote command and control Wireless security systems Remote Keyless Entry (RKE) Low power telemetry Low power FM receiver Home automation Remote sensing
UHF ASK/FSK Receiver:
* Single frequency receiver set by crystal frequency * Receive frequency range: Device rfRXD0420 RFRXD0920 Frequency Range 300 MHz to 450 MHz 800 MHz to 930 MHz
* Maximum data rate: - ASK: 80 Kbps NRZ - FSK: 40 Kbps NRZ * IF frequency range: 455 kHz to 21.4 MHz * RSSI range: 70 dB * Frequency deviation range: 5 kHz to 120 kHz * Maximum FM modulation frequency: 15 kHz
Bi-CMOS Technology:
* Wide operating voltage range * Low current consumption in Active and Standby modes - rfRXD0420 - 8.2 mA (typical, LNA High Gain mode) - <100 nA standby - RFRXD0920 - 9.2 mA (typical, LNA High Gain mode) - <100 nA standby * Wide temperature range: - Industrial: -40C to +85C
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 1
rfRXD0420/0920
1.0 DEVICE OVERVIEW
The rfRXD0420/0920 are low cost, compact single frequency short-range radio receivers requiring only a minimum number of external components for a complete receiver system. The rfRXD0420 covers the receive frequency range of 300 MHz to 450 MHz and the RFRXD0920 covers 800 MHz to 930 MHz. The rfRXD0420 and RFRXD0920 share a common architecture. They can be configured for Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), or FM modulation. The rfRXD0420/0920 are compatible with rfPICTM and rfHCS series of RF transmitters. * High frequency stability over temperature and power supply variations * Low spurious signal emission * High large-signal handling capability with selectable LNA gain control for improved dynamic range * Selectable IF bandwidth via external low cost ceramic IF filter. The IF Frequency range is selectable between 455 kHz to 21.4 MHz. This facilitates the use of readily available low cost 10.7 MHz ceramic IF filters in a variety of bandwidths. * ASK or FSK for digital data reception * FM modulation for analog signal reception * FSK/FM demodulation using quadrature detector (phase coincidence detector) * Received Signal Strength Indication (RSSI) for signal strength indication and ASK detection * Wide supply voltage range * Low active current consumption * Very low standby current The rfRXD0420/0920 is a single conversion superheterodyne architecture. A block diagram is illustrated in Figure 1-1. The rfRXD0420/0920 consists of: * Low-noise amplifier (LNA) - Gain selectable * Mixer for down-conversion of the RF signal to the Intermediate Frequency (IF) followed by an IF preamplifier * Fully integrated Phase-Locked Loop (PLL) frequency synthesizer for generation of the Local Oscillator (LO) signal. The frequency synthesizer consists of: - Crystal oscillator - Phase-frequency detector and charge pump - High-frequency Voltage Controlled Oscillator (VCO) - Fixed feedback divider - rfRXD0420 = divide by 16 - RFRXD0920 = divide by 32 * IF limiting amplifier to amplify and limit the IF signal and for Received Signal Strength Indication (RSSI) generation * Demodulator (DEMOD) section consists of a phase detector (MIXER2) and amplifier creating a quadrature detector (also known as a phase coincidence detector) to demodulate the IF signal in FSK and FM modulation applications * Operational amplifier (OPA) that can be configured as a comparator for ASK or FSK data decision or as a filter for FM modulation. * Bias circuitry for bandgap biasing and circuit shutdown
DS70090A-page 2
Preliminary
2003 Microchip Technology Inc.
FIGURE 1-1:
VSS
VSS
VDD 9
VSS 11
VDD 15
1IF+ 7 1IFIF Preamp
VDD 17
1IF IN
2IF IN 12
FBC1 13
1IF OUT 10
FBC2 14
2IF OUT 16
LNA GAIN
LNA OUT
VDD
MIXER1
MIXER2
32
DEM IN
DEMOD OPA + OPA19 OPA+ 20 RSSI Crystal Oscillator + 21
LNA IN LNA Fixed Divide by 16: rfRXD0420 32: RFRXD0920 Frequency Synthesizer Voltage Controlled Oscillator Phase Detector and Charge Pump
IF Limiting Amplifier with RSSI
rfRXD0420/0920 BLOCK DIAGRAM
LF
VDD
XTAL
VSS
ENRX
DEM OUT+
rfRXD0420/0920
24
DEM OUT-
29
28
27
26
25
23
22
VSS
Preliminary
Bias
31
VSS
30
OPA 18
2003 Microchip Technology Inc.
1 3 4 2 5 6 8
DS70090A-page 3
rfRXD0420/0920
TABLE 1-1:
Pin Name LNAGAIN LNAOUT 1IFIN 1IF+ 1IF1IFOUT 2IFIN FBC1 FBC2 2IFOUT DEMIN OPA OPAOPA+ RSSI DEMOUT+ DEMOUTXTAL ENRX LF LNAIN VDD VSS
rfRXD0420/0920 PINOUT I/O DESCRIPTION
Pin Number 2 3 4 6 7 9 11 12 13 15 16 18 19 20 21 23 24 26 28 29 31 8, 14, 17, 27, 32 1, 5, 10, 25, 30 Pin Type I O I --O I --O I O I I O O O I I I I P P Buffer Type CMOS Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog Analog CMOS Analog Analog Description LNA gain control (with hysteresis) LNA output (open collector) 1st IF stage input MIXER1 bias (open collector) MIXER1 bias (open collector) 1st IF stage output 2nd IF stage input Limiter IF Amplifier external feedback capacitor Limiter IF Amplifier external feedback capacitor 2nd IF stage output Demodulator input Operational amplifier output Operational amplifier input (negative) Operational amplifier input (positive) Received signal strength indicator output Demodulator output (positive) Demodulator output (negative) Crystal oscillator input Receiver enable input External loop filter connection. Common node of charge pump output and VCO tuning input. LNA input Positive supply Ground reference
Legend: I = Input, O = Output, I/O = Input/Output, P = Power, CMOS = CMOS compatible input or output
DS70090A-page 4
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
2.0 CIRCUIT DESCRIPTION
This section gives a circuit description of the internal circuitry of the rfRXD0420/0920 receiver. External connections and components are given in the APPLICATION CIRCUITS section. The PLL consists of a phase-frequency detector, charge pump, voltage-controlled oscillator (VCO), and fixed divide-by-16 (rfRXD0420) or divide-by-32 (RFRXD0920) divider. The rfRXD0420/0920 employs a charge pump PLL that offers many advantages over the classical voltage phase detector PLL: infinite pull-in range and zero steady state phase error. The charge pump PLL allows the use of passive loop filters that are lower cost and minimize noise. Charge pump PLLs have reduced flicker noise thus limiting phase noise. An external loop filter is connected to pin LF (Pin 29). The loop filter controls the dynamic behavior of the PLL, primarily lock time and spur levels. The application determines the loop filter requirements. The VCO gain for the rfRXD0420/0920 receivers are listed in Table 2-2.
2.1
Bias Circuitry
Bias circuitry provides bandgap biasing and circuit shutdown capabilities. The ENRX (Pin 28) modes are summarized in Table 2-1. The ENRX pin is a CMOS compatible input and is internally pulled down to Vss.
TABLE 2-1: BIAS CIRCUITRY CONTROL
ENRX(1) 0 1 Description Standby mode Receiver enabled
TABLE 2-2:
Device rfRXD0420 RFRXD0920
PLL PARAMETERS
KVCO(1) 250 MHz/V at 433 MHz 300 MHz/V at 868 MHz ICP(1) 60 A 60 A Divider 16 32
Note 1: ENRX has internal pull-down to Vss
2.2
Frequency Synthesizer
The Phase-locked Loop (PLL) frequency synthesizer generates the Local Oscillator (LO) signal. It consists of: * * * * Crystal oscillator Phase-frequency detector and charge pump Voltage Controlled Oscillator (VCO) Fixed feedback divider: - rfRXD0420 = divide by 16 - RFRXD0920 = divide by 32
Note 1: Typical value The LF pin is illustrated in Figure 2-2.
FIGURE 2-2:
BLOCK DIAGRAM OF LOOP FILTER PIN
2.2.1
CRYSTAL OSCILLATOR
LF 29
VDD
200
The internal crystal oscillator is a Colpitts type oscillator. It provides the reference frequency to the PLL. A crystal is normally connected to the XTAL (Pin 26) and ground. The internal capacitance of the crystal oscillator is 15 pF. Alternatively, a signal can be injected into the XTAL pin from a signal source. The signal should be AC coupled via a series capacitor at a level of approximately 600 mVpp. The XTAL pin is illustrated in Figure 2-1.
400 VSS 4 pF VSS VSS
2.3
Low Noise Amplifier
FIGURE 2-1:
BLOCK DIAGRAM OF XTAL PIN
VDD VDD 50 k XTAL 26 VSS VSS 30 pF 30 pF VSS 40 A VDD
The Low-Noise Amplifier (LNA) is a high-gain amplifier whose primary purpose is to lower the overall noise figure of the entire receiver thus enhancing the receiver sensitivity. The LNA is an open-collector cascode design. The benefits of a cascode design are: high gain with low noise high-frequency wide bandwidth low effective input capacitance with stable input impedance * high output resistance * high reverse isolation that provides improved stability and reduces LO leakage * * * *
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 5
rfRXD0420/0920
Approximate LNA noise figures are listed in Table 2-3.
TABLE 2-3:
LNA NOISE FIGURES
Noise Figure(1) TBD TBD
Device rfRXD0420 RFRXD0920 Note 1: Approximate value
The 1IF+ (Pin 6) and 1IF- (Pin 7) are bias connections to the MIXER1 balanced collectors. Both pins are open-collector outputs and are individually pulled up to VDD by a load resistor. The MIXER1 bias pins are illustrated in Figure 2-5. 1IFOUT (Pin 9) has an approximately 330 singleended output impedance. The 330 impedance provides a direct match to low cost ceramic IF filters. The 1IFOUT pins is illustrated in Figure 2-6.
LNAIN (Pin 31) has an input impedance of approximately 26 || 2 pF single-ended. LNAOUT (Pin 3) has an open-collector output and is pulled up to VDD via a tuned circuit. Important: To ensure LNA stability the VSS pin (Pin 1) must be connected to a low impedance ground. The LNA pins are illustrated in Figure 2-3.
FIGURE 2-4:
BLOCK DIAGRAM OF MIXER1 PIN
VDD
13
1IFIN 4 VSS 13 VSS 500 A
FIGURE 2-3:
BLOCK DIAGRAM OF LNA PINS
1.6V 0.8V LNAOUT 3 VSS VDD VSS
1IF+ 6 VSS
FIGURE 2-5:
BLOCK DIAGRAM OF MIXER1 BIAS PINS
VDD 20 pF VDD 20 pF 1IF7 VSS 500 A VSS VSS
VDD LNA IN 31 VSS
5 k
1 VSS
500 A
The gain of the LNA can be selected between High and Low Gain modes by the LNAGAIN pin (Pin 2). LNAGAIN is a CMOS input with hysteresis. Table 2-4 summarizes the voltage levels and modes for LNA gain. In the High Gain mode the LNA operates normally. In Low Gain mode the gain of the LNA is reduced approximately 25 dB, reduces total supply current, and increases maximum input signal levels (see Electrical Characteristics section for values).
FIGURE 2-6:
BLOCK DIAGRAM OF IF PREAMP PIN
VDD VDD 6.8 k 130 230 A VSS VSS VDD
1IFOUT 9
TABLE 2-4: LNA GAIN CONTROL
LNAGAIN < 0.8 V > 1.4 V Description High Gain mode Low Gain mode
2.5
IF Limiting Amplifier with RSSI
2.4
MIXER1 and IF Preamp
MIXER1 performs down-conversion of the RF signal to the Intermediate Frequency (IF) and is followed by an IF preamplifier. 1IFIN (Pin 4) has an approximately 33 single-ended input impedance. The 1IFIN pin is illustrated in Figure 24.
The IF Limiting Amplifier amplifies and limits the IF signal at the 2IFIN pin (Pin 11). It also generates the Received Signal Strength Indicator (RSSI) signal (Pin 21).
2.5.1
IF LIMITING AMPLIFIER
Magnitude control circuitry is used in the last stage of the receiver to keep the signal constant for demodulation. It can consist of a limiting or Automatic Gain Control (AGC) amplifier. A limiting amplifier is
DS70090A-page 6
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
employed in this design because it can handle a larger dynamic range while consuming less power with simple circuitry than AGC circuitry. The internal resistance of the 2IFIN pin is approximately 2.2 k. In order to terminate ceramic IF filters whose output impedance is 330 , a 390 resistor can be paralleled to the 2IFIN and FBC2 pins. FBC1 (Pin 12) and FBC2 (Pin 13) are connected to external feedback capacitors. The IF Limiting Amplifier pins are illustrated in Figures 2-7 and 2-8. For FSK and FM demodulation, the RSSI represents the received signal strength of the incoming RF signal. The RSSI pin is illustrated in Figure 2-9.
FIGURE 2-9:
BLOCK DIAGRAM OF RSSI PIN
VDD RSSI 21 36 k VSS VSS 50 I (Pi)
FIGURE 2-7:
BLOCK DIAGRAM OF IF LIMITING AMPLIFIER INPUT PINS
VDD FBC1 12
2.6
Demodulator
VDD 2IFIN 11 VSS VDD FBC2 13 VSS
2.2 k
2.2 k 200 A Vss
VSS
The demodulator (DEMOD) section consists of a phase detector (MIXER2) and amplifier creating a quadrature detector (also known as a phase coincidence detector) to demodulate the IF signal in FSK and FM modulation applications. The quadrature detector provides all the IF functions required for FSK and FM demodulation with only a few external parts. The in-phase signal comes directly from the output of the IF limiting amplifier to MIXER2. The quadrature signal is created by an external tuned circuit from the output of the IF limiting amplifier (2IFOUT, Pin 15) ACcoupled to the MIXER2 DEMIN (Pin 16) input. The input impedance of the DEMIN pin is approximately 47 k. The external tuned circuit can be constructed from simple inductor-capacitor (LC) components but will require one of the elements to be tunable. A no-tune solution can be constructed with a ceramic discriminator. The output voltage of the DEMOD amplifier (DEMout+ and DEMout-, Pins 23 and 24) depends on the peak deviation of the FSK or FM signal and the Q of the external tuned circuit. DEMout+ and DEMout- are high impedance outputs with only a 20 A current capability. The Demodulator pins are illustrated in Figures 2-10 and 2-11.
FIGURE 2-8:
BLOCK DIAGRAM OF IF LIMITING AMPLIFIER OUTPUT PIN
VDD 2IFOUT 15 VSS 40 A VSS VDD
2.5.2
RECEIVED SIGNAL STRENGTH INDICATOR (RSSI)
FIGURE 2-10: BLOCK DIAGRAM OF DEMODULATOR INPUT PIN
VDD VDD 47 k DEM IN 16 VSS VDD
The RSSI signal is proportional to the log of the signal at 2IFIN. The 2IFIN input RSSI range is approximately 40 V to 160 mV. The slope of the RSSI output is approximately 26 mV/dB of RF signal. The RSSI output has an internal 36 k resister to Vss fed by a current source. This resistor converts the RSSI current to voltage. For Amplitude Shift Keying (ASK) demodulation, RSSI is compared to a reference voltage (static or dynamic). Post detector filtering is easily implemented by connecting a capacitor to ground from the RSSI pin effectively creating an RC filter with the internal 36 k resistor.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 7
rfRXD0420/0920
FIGURE 2-11: BLOCK DIAGRAM OF DEMODULATOR OUTPTUT PINS
VDD DEM OUT+ 23 VSS VDD DEM OUT24 VSS 50 20 A VSS 20 A VSS 50 20 A VSS 20 A VSS
2.7
Operational Amplifier
The internal operational amplifier (OPA) can be configured as a comparator for ASK or FSK or as a filter for FM modulation applications. The Op Amp pins are illustrated in Figures 2-12 and 2-13.
FIGURE 2-12: BLOCK DIAGRAM OF OP AMP INPUT PINS
VDD VDD OPA19 VSS VSS 50 20 A 50 VDD OPA+ 20
FIGURE 2-13: BLOCK DIAGRAM OF OP AMP OUTPUT PIN
VDD OPA 18 VSS 50 VDD
VSS
DS70090A-page 8
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
3.0 APPLICATION CIRCUITS
This section provides general information on application circuits for the rfRXD0420/0920 receiver. The following connections and external components provide starting points for designs and list the minimum circuitry recommended for general purpose applications. Performance of the radio system (transmitter and receiver) is affected by component selection and the environment in which it operates. Each system design has its own unique requirements. Specifications for a particular design requires careful analysis of the application and compromises for a practical implementation. effect the trim capacitor has on the receive frequency for the rfRXD0420 at 433.92 MHz. Keep in mind that this graph represents one example circuit and the actual results depends on the crystal and PCB layout.
FIGURE 3-2:
Receive Frequency (MHz) 434.10 434.05 434.00 433.95 433.90 433.85 433.80 433.75 0 ohms 82 pF 68 pF
RECEIVE FREQUENCY VS. TRIM CAPACITANCE
56 pF
47 pF
39 pF
33 pF
27 pF
22 pF
18 pF
15 pF
12 pF
10 pF
This subsection lists connections and components that are common between applications. The following subsections give specific circuit connections and components for ASK, FSK and FM applications.
Trim Capacitor (pF)
3.1.1
BYPASS CAPACITORS
Note that a 0 resistor, in the lower left of the graph, represents an infinite capacitance. This will be the lowest frequency obtainable for the crystal and PCB combination. Calculation of the crystal frequency requires knowledge of the receive frequency (frf) and intermediate frequency (fif). Figure 3-3 is a worksheet to assist the designer in calculating the crystal frequency. Table 3-1 lists crystal frequencies for popular receive frequencies. Table 3-2 lists crystal parameters required for ordering crystals. For background information on crystal selection see Application Note AN826, Crystal Oscillator Basics and Crystal Selection for rfPICTM and PICmicro(R) Devices.
Bypass capacitors should be placed as physically close as possible to VDD pins 8, 14, 17, 27 and 32 respectively. Additional bypassing and board level lowpass filtering of the power supply may be required depending on the application.
3.1.2
FREQUENCY PLANNING
The rfRXD0420/0920 receivers are single-conversion superheterodyne architecture with a single IF frequency. The receive frequency is set by the crystal frequency (fXTAL) and intermediate frequency (fif). For a majority of applications an external crystal is connected to XTAL (Pin 26). Figure 3-1 illustrates an example circuit with an optional trim capacitor.
TABLE 3-1: CRYSTAL FREQUENCIES FOR POPULAR RECEIVE FREQUENCIES
Receive Frequency rfRXD0420 315 MHz 20.35625 MHz (2) 26.45125 MHz (1) RFRXD0920 868.3 MHz 915 MHz 26.8 MHz (1) 28.259375 MHz (1) 433.92 MHz Crystal Frequency
FIGURE 3-1:
XTAL EXAMPLE CIRCUIT WITH OPTIONAL TRIM CAPACITOR
XTAL
26
C TRIM (OPTIONAL) X1
(1) Low-side injection (2) High-side injection
TABLE 3-2: CRYSTAL PARAMETERS
Parameter The crystal load capacitance should be specified to include the internal load capacitance of the XTAL pin of 15 pF plus PCB stray capacitance (approximately 2 to 3 pF). A trim capacitor can be used to trim the crystal on frequency within the limitations of the crystal's trim sensitivity and pullability. Figure 3-2 illustrates the Frequency: Mode: Load Capacitance: ESR: Value (see Figure 3-1) Fundamental 15-20 pF 60 Maximum
These values are for design guidance only.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 9
5 pF
3.1
General
rfRXD0420/0920
FIGURE 3-3: FREQUENCY PLANNING WORKSHEET
Step 1: Identify receive (frf) and IF frequency (fif). frf frf = ____________________ flo fif = ____________________ fXTAL x PLL divide ratio Step 2: Calculate crystal frequencies for high- and low-side injection: High-side Injection fif
fXTAL-HIGH =
( (
frf
+
fif
) )
PLL divide ratio
=
( _________ ( _________
+ _________
) )
16 if rfRXD0420 32 if RFRXD0920
= _______________
Low-side Injection frf fif - _________
fXTAL-LOW =
PLL divide ratio
=
16 if rfRXD0420 32 if RFRXD0920
= _______________
Step 3: Calculate Local Oscillator (LO) frequencies (flo) using fXTAL-HIGH and fXTAL-LOW: High-side Injection flo-HIGH = fXTAL-HIGH x PLL Divide Ratio = _________ x 16 if rfRXD0420 32 if RFRXD0920 = _____________
Low-side Injection flo-LOW = fXTAL-LOW x PLL Divide Ratio = _________ x 16 if rfRXD0420 32 if RFRXD0920 = _____________
Step 4: Select high-side injection (flo-HIGH) or low-side injection (flo-LOW) that corresponds to the LO frequency that is between the ranges of: Device rfRXD0420 RFRXD0920 LO Frequency Range 300 to 430 MHz 800 to 915 MHz
Step 5: From the chosen injection mode in Step 4, write the selected crystal frequency (fXTAL) and circle injection mode. (circle one) fXTAL = ____________________ High-side Injection Low-side Injection
Step 6: Calculate image frequency (frf-image) for the Injection mode chosen: if High-side Injection frf-image = frf + (2 x fif) = ___________ + ( 2 x ___________ ) = ______________
if Low-side Injection frf-image = Note: frf - (2 x fif) = ___________ - ( 2 x ___________ ) = ______________
Image frequency should be sufficiently filtered by the preselector for the application.
DS70090A-page 10
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
3.1.3 PLL LOOP FILTER
An external PLL loop filter is connected to pin LF (Pin 29). The loop filter controls the dynamic behavior of the PLL, primarily lock time and spur levels. Generally, the PLL lock time is a small fraction of the overall receiver start-up time (see Electrical Characteristics Section). The crystal oscillator is the largest contributor to start-up time. Thus, for the majority of applications, design loop filter values for a wide loop bandwidth to suppress noise. Figure 3-4 illustrates an example filter circuit for a wide frequency range suitable for a majority of applications. The SAW filter has the added advantage of filtering wide-band noise and improving the signal-to-noise ratio (SNR) of the receiver. SAW filters require impedance matching. Refer to the manufacturers' data sheet and application notes for SAW filter pinouts, specified impedances and recommended matching circuits. Figure 3-5 shows a SAW filter example circuit. A secondary purpose of the preselector is to provide impedance matching between the antenna and LNAIN (Pin 31).
3.1.5 FIGURE 3-4: PLL LOOP FILTER EXAMPLE CIRCUIT
29 LF
ANTENNA
C2 OPTIONAL
C1 1000 pF R1 10 k
Receiver performance and device packaging influence antenna selection. There are many third-party antennas to choose from. Third-party antennas typically have an impedance of 50 . The preselector components should be chosen to match the impedance of the antenna to the LNAIN (Pin 31) impedance of 26 || 2 pF. The designer can chose to use a simple wire antenna. The length of the wire should be one-quarter the wavelength () of the receive frequency. For example, the wavelength of 433.92 MHz is: = c / frf where c = 3 x 108 m/s = 3 x 108 m/s / 433.92 x 106 Hz
3.1.4
PRESELECTOR
= 0.69 m therefore 0.25 = 17.3 cm or 6.8 inches Finally, the wire antenna should be impedance matched to the preselector. The typical impedance of a one-quarter wavelength wire antenna is 36 .
Receiver performance is heavily influenced by the preselector (also known as the front-end filter). The purpose of the preselector is to filter unwanted signals and noise from entering the receiver. The most important unwanted signal is the image frequency (frf-image). Pay particular attention to the image frequency calculated in Figure 3-3 as this will be the frequency that needs to be filtered out by the preselector. The preselector can be designed using a simple LC filter or a Surface Acoustic Wave (SAW) filter. A simple LC filter provides a low cost solution but will have the least effect filtering the image frequency. A SAW filter can effectively filter the image frequency with a minimum of 40 dB attenuation.
3.1.6
LNA GAIN
For a majority of applications, LNAGAIN can be tied to Vss (ground) enabling High Gain mode. If the application requires short range communications, LNAGAIN can be tied to VDD (pulled up) enabling Low Gain mode. More Information on LNAGAIN operation can be found in the Circuit Description section.
FIGURE 3-5:
SAW FILTER EXAMPLE CIRCUIT
L1 Antenna C1 F1 SAW Filter 2 Input Output 5 1 Input Gnd Output Gnd 6 Case Gnd 3478 L2 LNAIN C2
Note:
Refer to SAW filter manufacturer's data sheet for pin outs and values for impedance matching components.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 11
rfRXD0420/0920
3.1.7 LNA TUNED CIRCUIT 3.1.8 MIXER1 BIAS
The LNAOUT (Pin 3) has an open-collector output. It is pulled up to VDD via a tuned circuit. It is also connected to 1IFIN (Pin 4) via a series decoupling capacitor. The 1IFIN input impedance is approximately 33 || 1.5 pF. Important: To ensure LNA stability the VSS pin (Pin 1) must be connected to a low impedance ground. As shown in Figure 3-6, components C1 and L1 make up the tuned circuit and provide collector current via pull-up. Together with decoupling capacitor C2, they provided impedance matching between the LNA and MIXER1. To a lesser extent, C1, L1, and C2 provide band-pass filtering at the receive frequency (frf). Component values depend on the selected receive frequency. The challenge is to design the circuit with the fewest components setting Q as high as possible as limited by component tolerances. For a majority of applications it is best to design a wide bandwidth tuned circuit to account for manufacturing and component tolerances. The best approach is to design the tuned circuit using a filter simulation program. Table 3-3 lists example component values for popular receive frequencies. The 1IF+ (Pin 6) and 1IF- (Pin 7) are bias connections to the MIXER1 balanced collectors. Both pins are open-collector outputs and are individually pulled up to VDD by a load resistor. Figure 3-7 shows a MIXER1 bias example circuit.
FIGURE 3-7:
MIXER1 BIAS EXAMPLE CIRCUIT
VDD VDD
R1 470
R2 470
1IF+
3.1.9
INTERMEDIATE FREQUENCY (IF) FILTER
FIGURE 3-6:
LNA OUTPUT TO MIXER1 EXAMPLE CIRCUIT.
VDD
The IF filter defines the overall adjacent signal selectivity of the receiver. For a majority of applications, lowcost 10.7 MHz ceramic IF filters are used. These are available in a variety of bandwidths and packages. IF filter bandwidth selection is a function of: * modulation (ASK, FSK or FM) * signal bandwidth * frequency and temperature tolerances of the transmitter and receiver components The typical input and output impedance of ceramic filters is 330 . 1IFOUT (Pin 9) has an approximately 330 single-ended output impedance and provides a direct match to the ceramic IF filter. The internal resistance of the 2IFIN (Pin 11) is approximately 2.2 k. In order to terminate ceramic IF filters a 390 resistor can be paralleled to the 2IFIN and FBC2 (Pin 13). Figure 3-8 shows an example circuit schematic using a 10.7 MHz ceramic IF filter.
C Bypass
C1
L1 C2
LNAOUT
1IF IN
3
4
3.1.10 IF LIMITING AMPLIFIER EXTERNAL FEEDBACK CAPACITORS TABLE 3-3: LNA TUNED CIRCUIT EXAMPLE COMPONENT VALUES
frf 315 MHz 433.92 MHz 868.3 MHz 915 MHz C1 7.0 pF 3.0 pF 2.0 pF 2.0 pF L1 22 nH 15 nH 7.6 nH 6.8 nH C2 6.0 pF 6.0 pF 3.0 pF 3.0 pF FBC1 (Pin 12) and FBC2 (Pin 13) are connected to external feedback capacitors. Figure 3-8 shows component values and connections for these capacitors.
These values are for design guidance only.
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Preliminary
2003 Microchip Technology Inc.
1IF-
6
7
FIGURE 3-8:
1000 pF 13 FBC2 390 33000 pF 2.2 k 2.2 k
IF Preamp Ceramic Filter 10.7 MHz 1000 pF + IF Limiting Amplifier with RSSI R1 50 12 FBC1 11 2IFIN
2IFOUT
DEM IN DEMOD + MIXER2 23 DEM OUT+ 24 DEM OUT-
2003 Microchip Technology Inc.
External Feedback Capacitors 15 16 RSSI 21 R2 36 k
IF FILTER, LIMITING AMPLIFIER AND DEMODULATOR BLOCK DIAGRAM
Preliminary
9 1IF OUT
rfRXD0420/0920
DS70090A-page 13
+V
+V
+V
+V
+V
FIGURE 3-9:
C15 C17 33000 pF R5 470 R4 470 C8 R2 390
L3
F2 10.7 MHz
C13 1000 pF
VDD
VSS
VDD
VSS
VSS
1IF+
1IF-
VDD
OPA
2IF IN
FBC1
1IF OUT
LNA GAIN
LNA OUT
IF Preamp MIXER1
2IF OUT
VDD
DEMOD OPA + OPA19 OPA+ 20 RSSI Crystal Oscillator + 21 C1 1800 pF
ASK APPLICATION CIRCUIT
ANT Fixed Divide by 16: rfRXD0420 32: RFRXD0920 Frequency Synthesizer Voltage Controlled Oscillator Phase Detector and Charge Pump
LNA IN LNA
IF Limiting Amplifier with RSSI
31
MIXER2
C14 330 pF
32
DEM IN
+V
1IF IN
FBC2
LF
VDD
XTAL
VSS
ENRX
DEM OUT-
29 +V
28
27
26 +V
25
24
23 NC C9 OPTIONAL CRYSTAL TRIM CAPACITOR
NC
C10 OPTIONAL LOOP FILTER CAPACITOR R3 10 k
C11 1000pF C3 330 pF
2003 Microchip Technology Inc.
X1
DEM OUT+
22
VSS
DS70090A-page 14
C18 330 pF C12 1000 pF C16 330 pF C7 330pF C4 330pF RxDATA NC 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 NC 18 C2 47000 pF R1 100 k Bias
rfRXD0420/0920
1
Preliminary
TO ANTENNA MATCHING NETWORK
VSS
30
rfRXD0420/0920
3.2 Amplitude Shift Keying (ASK)
Figure 3-9 illustrates an example ASK applications circuit. The IF Limiting Amplifier with RSSI is used as an ASK detector. The RSSI signal is post detector filtered and then compared to a reference voltage to determine if the incoming RF signal is a logical one or zero. The reference voltage can be configured as a dynamic voltage level determined by the incoming RF signal strength or by a predetermined fixed level. If the bit decision occurs near the end of the signal period, then the time constant should be set at less than or equal to the signal period. Figure 3-11 illustrates this method. Once the signal decision time and time period of the signal period are known, then capacitor C1 can be selected. Once C1 is selected, the designer should observe the RSSI signal with an oscilloscope and perform operational and/or bit error rate testing to confirm receiver performance.
3.2.1
RSSI POST DETECTOR FILTERING
The RSSI signal is low-passed filtered to remove high frequency and pulse noise to aid the decision making process of the comparator and increase the sensitivity of the receiver. The RSSI signal low-pass filter is a RC filter created by the RSSI output impedance of 36 k and capacitor C1. Setting the time constant (RC = ) of the RC filter depends on the signal period and when the signal decision will be made.
FIGURE 3-11: NEAR END OF THE SIGNAL PERIOD DECISION RSSI LOWPASS FILTERED
Signal Decision
OOK Signal
3.2.1.1
Signal Period
Signal Period
Optimum sensitivity of the receiver with reasonable pulse distortion occurs when the RC filter time constant is between 1 and 2 times the signal period. If the time constant of the RC filter is set too short, there is little noise filtering benefit. However, if the time constant of the RC filter is set too long, the data pulses will become elongated causing inter-symbol interference.
RSSI Signal
1 to 2
3.2.1.2
Signal Decision
3.2.2
COMPARATOR
If the bit decision occurs in the center of the signal period (such as KEELOQ decoders), then one or two times the RC filter time constant should be set at less than or equal to half the signal period. Figure 3-10 illustrates this method. The top trace represents the received on-off keying (OOK) signal. The bottom trace shows the RSSI signal after the RC low-pass filter.
The internal operational amplifier is configured as a comparator. The RSSI signal is applied to OPA+ (Pin 20) and compared with a reference voltage on OPA(Pin 19) to determine the logic level of the received signal. The reference voltage can be dynamic or static. The choice of dynamic versus static reference voltage depends in part on the ratio of logical ones versus zeros of the data (this can also be thought of as the AC content of the data). Provided the ratio has an even number of logical ones versus zeros, a dynamic reference voltage can be generated with a simple low-pass filter. The advantage of the dynamic reference voltage is the increased receiver sensitivity compared to a fixed reference voltage. However, the comparator will output random data. The decoder (for example, a programmed PICmicro MCU or KEELOQ decoder) must distinguish between random noise and valid data. The choice of a static reference voltage depends in part on the DC content of the data. That is, the data has an uneven number of logical ones versus zeros. The disadvantage of the static reference voltage is decreased receiver sensitivity compared to a dynamic reference voltage. In this case, the comparator will output data without random noise.
FIGURE 3-10: CENTER SIGNAL PERIOD DECISION RSSI LOW-PASS FILTERED
Signal Decision
OOK Signal
Signal Period
RSSI Signal
1 to 2
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 15
rfRXD0420/0920
3.2.2.1 DYNAMIC REFERENCE VOLTAGE
A dynamic reference voltage can be derived by averaging the received signal with a low-pass filter. The example ASK application circuit shown in Figure 3-9, the low-pass filter is formed by R1 and C2. The output of the low-pass filter is then fed to OPA-. The setting of the R1-C2 time constant depends on the ratio of logical ones versus zeros and a trade off in stability versus receiver reaction time. If the received signal has an even number of logical ones versus zeros, the time constant can be set relatively short. Thus the reference voltage can react quickly to changes in the received signal amplitude and differences in transmitters. However, it may not be as stable and can fluctuate with the ratio of logical ones and zeros. If the time constant is set long, the reference voltage will be more stable. However, the receiver cannot react as quickly upon the reception of a received signal. Selection of component values for R1 and C2 is an iterative process. First start with a time constant between 10 to 100 times the signal rate. Second, view the reference voltage against the RSSI signal to determine if the values are suitable. Figure 3-12 is an oscilloscope screen capture of an incoming RF square wave modulated signal (ASK on-off keying). The top trace is the data output of OPA (Pin 18). The two bottom traces are the RSSI signal (Pin 21, bottom square wave) and generated reference voltage (Pin 19, bottom trace centered in the RSSI square wave). The goal is to select values for R1 and C2 such that the reference voltage is in the middle of the RSSI signal. This reference voltage level provides the optimum data comparison of the incoming data signal.
3.2.2.2
STATIC REFERENCE VOLTAGE
A static reference voltage can be derived by a voltage divider network.
FIGURE 3-12:
RSSI AND REFERENCE VOLTAGE COMPARISON
OPA (Pin 18)
RSSI OPA(Pin 19) (Pin 21)
DS70090A-page 16
Preliminary
2003 Microchip Technology Inc.
+V F3
+V
+V
+V
C18 330 pF C31 10-12 pF C13 1000 pF C12 1000 pF F2 10.7 MHz C15 C17 1.0 pF 33000 pF 680 pF VSS VDD VSS VDD VDD 1IF+ 1IF1IF IN 2IF IN FBC1 FBC2 OPA 2 3 IF Preamp MIXER1 1IF OUT 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 C32 C4 330 pF R5 470 C8 R4 470 R2 390 +V C33 L3
LNA GAIN
LNA OUT
2IF OUT
FIGURE 3-13: FSK APPLICATION CIRCUIT
VDD
ANT
LNA IN LNA Fixed Divide by 16: rfRXD0420 32: RFRXD0920 Frequency Synthesizer Voltage Controlled Oscillator Phase Detector and Charge Pump Crystal Oscillator
IF Limiting Amplifier with RSSI
MIXER2
C14 330 pF
32
DEM IN
+V
VSS
LF
VDD
XTAL
ENRX
VSS
DEM OUT-
+V
+V
C10 OPTIONAL LOOP FILTER CAPACITOR
C11 1000 pF R3 10 k C3 330 pF
C9 OPTIONAL CRYSTAL TRIM CAPACITOR X1 C1 10-47 pF
DEM OUT+
29
28
27
26
25
24
23
22
rfRXD0420/0920
DS70090A-page 17
NOTE: Demodulator output low-pass capacitors C2 dependent on signal rate 10-47 pF
VSS
2003 Microchip Technology Inc.
C16 330 pF C7 330 pF
RxDATA DEMOD
1
OPA +OPA19 OPA+ 20 RSSI 21 +
RSSI
31
Preliminary
Bias
TO ANTENNA MATCHING NETWORK
C30 330 pF
VSS
30
rfRXD0420/0920
3.3 Frequency Shift Keying (FSK)
Figure 3-13 illustrates an example FSK application circuit.
FIGURE 3-14: LC DISCRIMINATOR EXAMPLE CIRCUIT
R1 4.7 k C3 0-56 pF
3.3.1
IF FILTER CONSIDERATIONS
As mentioned in the Section 3.1 above, IF filter bandwidth selection is a function of: * modulation (ASK, FSK or FM) * signal bandwidth * frequency and temperature tolerances of the transmitter and receiver components The occupied bandwidth of binary FSK signals is 2 times the peak frequency deviation plus 2 times the signal bandwidth. For example, if the data rate is 2400 bits per second Manchester encoded, the signal bandwidth is 4800 baud or 1200 Hz, and if the peak frequency deviation is 24 kHz, the minimum bandwidth of the IF filter is: IF BWmin = (2 x 2400) + (2 x 24000) IF BWmin = 52800 Hz Add to this value the frequency and temperature tolerances of the transmitter and receiver components. FSK signals are more sensitive to group delay variations of the IF filter. Therefore, a filter with a low group delay variation should be used. As an alternative, a filter with wider than required bandwidth can be used because the group delay variation in the center of the bandpass will be relatively constant.
15 C1 1.0 pF
L1 3.3 H C2 680 pF
2IF OUT
3.3.2.2
Ceramic Discriminator
A no-tune solution can be constructed with a ceramic discriminator. Figure 3-15 illustrates an example ceramic discriminator circuit. The ceramic discriminator acts as a parallel tuned circuit at the IF frequency (for example, 10.7 MHz). The parallel capacitor C3 tunes the ceramic resonator. The high Q of this circuit enables higher output of the detector for small frequency deviations. However, smaller frequency deviations require better frequency tolerances at the transmitter and receiver. In order to detect wider deviation or off-frequency signals, the detector bandwidth has to be increased. This can be accomplished by reducing the Q of the tuned circuit. One method is to parallel a resistor across the ceramic discriminator. A second is to increase the value of the coupling capacitor C1 increasing the load on the detector. The result of reducing the Q of the discriminator will be that the detector output will be smaller.
3.3.2
FSK DETECTOR
The demodulator (DEMOD) section consists of a phase detector (MIXER2) and amplifier creating a quadrature detector (also known as a phase coincidence detector) to demodulate the IF signal in FSK and FM modulation applications. The in-phase signal comes directly from the output of the IF limiting amplifier to MIXER2. The quadrature signal is created by an external tuned circuit from the output of the IF limiting amplifier (2IFOUT, Pin 15) AC-coupled to the MIXER2 DEMIN (Pin 16) input.
FIGURE 3-15: CERAMIC DISCRIMINATOR EXAMPLE CIRCUIT
F1 CERAMIC DISCRIMINATOR
3.3.2.1
LC Discriminator
The external tuned circuit can be constructed from simple inductor-capacitor (LC) components. This type circuit produces and excellent output. However, one of the elements (L or C) must be tunable. Figure 3-14 illustrates an example LC discriminator circuit using a tunable capacitor. A similar circuit with a tunable inductor is also possible. Resistor R1 = 4.7 k reduces the Q of the circuit so that frequency deviations of up to 75 kHz can be demodulated.
C1 1.0 pF
DEM IN
16
C3 10-12 pF
C2 680 pF 2IF OUT DEM IN 15 16
DS70090A-page 18
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
3.3.3 POST DETECTOR FILTERING
Care should be taken in selecting the values of capacitors C1 and C2 (Figure 3-13) so that the output of the detector is not distorted and receiver sensitivity improved. These values are chosen depending on the data signal rate. Generally, if the data signal rate is fast then the filter time constant can be set short. Conversely, if the signal rate is slow, the filter time constant can be set long. The designer should observe the output of the detector with an oscilloscope and perform operational and/or bit error rate testing to confirm receiver performance.
3.3.4
COMPARATOR
The output of the DEMOD amplifier (DEMOUT+ and DEMOUT-, Pins 23 and 24) depends on the peak deviation of the FSK or FM signal and the Q of the external tuned circuit. DEMout+ and DEMout- are high impedance outputs with only a 20 A current capability. The capacitance on these pins limit the maximum data signal rate. The nominal output voltage of these pins is 1.23V.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 19
+V F3
+V
+V
+V
C13 1000 pF
VSS
VSS
VDD
VSS
VDD
1IF+
1IF-
VDD
1IF IN
2IF IN
FBC1
FBC2
OPA
LNA GAIN
LNA OUT
FIGURE 3-16: FM APPLICATION CIRCUIT
VDD
MIXER1
IF Preamp
1IF OUT
C14 IF Limiting Amplifier with RSSI Frequency Synthesizer
32
DEM IN
+V
2IF OUT
MIXER2
LF
VDD
XTAL
VSS
ENRX
DEM OUT-
29 +V C11 1000 pF R3 10 k C3 330 pF
28
27
26 +V
25
24
23 NC
DEMOUT+
22
2003 Microchip Technology Inc.
C18 OPTIONAL LOOP FILTER CAPACITOR
C9 OPTIONAL CRYSTAL TRIM CAPACITOR X1
VSS
DS70090A-page 20
C1 330 pF C31 10-12 pF C12 1000 pF L3 C17 1.0 pF C32 33000 pF 680 pF C4 330 pF RxAudio R5 470 R2 390 C8 +V R4 470 F1 10.7 MHz C33 C16 330 pF C4 330 pF 3 5 15 16 6 7 8 9 10 11 12 13 14 17 4 18 RSSI C30 330 pF DEMOD OPA + OPA19 OPA+ 20 RSSI 21 + R32 33 k C35 100 pF C34 100 pF R31 12 k R30 6.8 k Fixed Divide by 16: rfRXD0420 32: RFRXD0920 Voltage Controlled Oscillator Phase Detector and Charge Pump Crystal Oscillator Bias R33 33 k
rfRXD0420/0920
C15
1
2
330 pF
Preliminary
ANT
LNAIN
TO ANTENNA MATCHING NETWORK
31
LNA
VSS
30
rfRXD0420/0920
3.4 Frequency Modulation (FM)
Figure 3-16 illustrates an example FM application circuit.
3.4.1
FSK DETECTOR
FM demodulation is performed in the same manner as described in the FSK section above.
3.4.2
OPERATIONAL AMPLIFIER
The internal operational amplifier is configured as an active low-pass filter. FM audio is typically de-emphasized. It is recommended that de-emphasis circuitry be connected at the output of the operational amplifier rather than the output of the detector.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 21
rfRXD0420/0920
4.0 ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings Supply voltage...................................................................................................................................................0 to +7.0V Input voltage...........................................................................................................................................-0.3 to VCC+0.3V Input RF level .........................................................................................................................................................10dBm Storage temperature .................................................................................................................................... -40 to +125C
NOTICE: Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
DS70090A-page 22
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
4.1 DC Characteristics: rfRXD0420 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating Temperature -40C TA +85C Characteristic Supply Voltage Standby Current Supply Current Op Amp input voltage offset Op Amp input current offset Op Amp input bias current RSSI voltage 5.0 6.5 VOPA IOPA IBIAS VRSSI *
DC CHARACTERISTICS Param No. Sym VCC ISTBY ICC
Min 2.5 2.7
Typ -- -- 6.5 8.2 -- -- 1.0 1.9
Max 5.5 5.5 100 8.0 10.0 20 50 100 1.5 2.45
Units V V nA mA mA mV nA nA V V
Conditions frf < 400 MHz frf > 400 MHz ENRX = 0 LNAGAIN = 1 LNAGAIN = 0
-20 -50 -100 0.5 1.25
LNAGAIN = 1 LNAGAIN = 0
These parameters are characterized but not tested. Data in "Typ" column is at 3V, 23C unless otherwise stated. These parameters are for design guidance only and are not tested.
4.2
AC Characteristics: rfRXD0420 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating Temperature -40C TA +85C Characteristic Start-up time - FSK/FM Start-up time - ASK Sensitivity - Narrowband FSK Sensitivity - Wideband FSK Sensitivity - Narrowband ASK Sensitivity - Wideband ASK Input RF level maximum FSK/ FM Input RF level maximum ASK -111 -104 -109 -106 0 -10 Min Typ Max 0.9 R1xC1 +TFSK Units ms ms dBm dBm dBm dBm dBm dBm Conditions ENRX = 0 to 1 Note 1 Note 2 Note 3 Note 4 Note 5 LNAGAIN = 1 LNAGAIN = 1
AC CHARACTERISTICS Param No. Sym TFSK TASK
*
These parameters are characterized but not tested. Data in "Typ" column is at 3V, 23C, frf = 433.6 MHz, IF = 10.7 MHz unless otherwise stated. These parameters are for design guidance only and are not tested. 2: IF bandwidth = 40 kHz, f = +/- 15 kHz, BER <= 3 x 10-3 3: IF bandwidth = 150 kHz, f = +/- 50 kHz, BER <= 3 x 10-3 4: IF bandwidth = 40 kHz, BER <= 3 x 10-3 5: IF bandwidth = 150 kHz, BER <= 3 x 10-3
Note 1: Dependant on ASK detector time constant.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 23
rfRXD0420/0920
4.3 DC Characteristics: RFRXD0920 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating Temperature -40C TA +85C Characteristic Supply Voltage Standby Current Supply Current Op Amp input voltage offset Op Amp input current offset Op Amp input bias current RSSI voltage 6.0 7.5 VOPA IOPA IBIAS VRSSI *
DC CHARACTERISTICS Param No. Sym VCC ISTBY ICC
Min 2.5 3.3
Typ -- -- 7.5 9.2 -- -- 1.0 1.9
Max 5.5 5.5 100 9.0 11.0 20 50 100 1.5 2.45
Units V V nA mA mA mV nA nA V V
Conditions frf < 900 MHz frf > 900 MHz ENRX = 0 LNAGAIN = 1 LNAGAIN = 0
-20 -50 -100 0.5 1.25
LNAGAIN = 1 LNAGAIN = 0
These parameters are characterized but not tested. Data in "Typ" column is at 3V, 23C unless otherwise stated. These parameters are for design guidance only and are not tested.
4.4
AC Characteristics: RFRXD0920 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating Temperature -40C TA +85C Characteristic Start-up time - FSK/FM Start-up time - ASK Sensitivity - Narrowband FSK Sensitivity - Wideband FSK Sensitivity - Narrowband ASK Sensitivity - Wideband ASK Input RF level maximum FSK/ FM Input RF level maximum ASK -109 -102 -108 -104 0 -10 Min Typ Max 0.9 R1xC1 + TFSK Units ms ms dBm dBm dBm dBm dBm dBm Conditions ENRX = 0 to 1 Note 1 Note 2 Note 3 Note 4 Note 5 LNAGAIN = 1 LNAGAIN = 1
AC CHARACTERISTICS Param No. Sym TFSK TASK
*
These parameters are characterized but not tested. Data in "Typ" column is at 3V, 23C, frf = 433.6 MHz, IF = 10.7 MHz unless otherwise stated. These parameters are for design guidance only and are not tested. 2: IF bandwidth = 40 kHz, f = +/- 15 kHz, BER <= 3 x 10-3 3: IF bandwidth = 150 kHz, f = +/- 50 kHz, BER <= 3 x 10-3 4: IF bandwidth = 40 kHz, BER <= 3 x 10-3 5: IF bandwidth = 150 kHz, BER <= 3 x 10-3
Note 1: Dependant on ASK detector time constant.
DS70090A-page 24
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
5.0 PACKAGING INFORMATION
5.1 Package Marking Information
32-Lead LQFP
Example
XXXXXXXXXXXX XXXXXXXXXXXX XXXXXXXXXXXX YYWWNNN
rfRXD0420 02123ABC
Legend:
XX...X Y YY WW NNN
Customer specific information* Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week `01') Alphanumeric traceability code
Note:
In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line thus limiting the number of available characters for customer specific information.
*
Standard PICmicro device marking consists of Microchip part number, year code, week code, and traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP price.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 25
rfRXD0420/0920
5.2 Package Details
The following section gives the technical details of the package. 32-Lead Plastic Low Profile Quad Flat Package (LQ) 7 x 7 x 1.4 mm Body Not available at this time.
DS70090A-page 26
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
ON-LINE SUPPORT
Microchip provides on-line support on the Microchip World Wide Web site. The web site is used by Microchip as a means to make files and information easily available to customers. To view the site, the user must have access to the Internet and a web browser, such as Netscape(R) or Microsoft(R) Internet Explorer. Files are also available for FTP download from our FTP site.
SYSTEMS INFORMATION AND UPGRADE HOT LINE
The Systems Information and Upgrade Line provides system users a listing of the latest versions of all of Microchip's development systems software products. Plus, this line provides information on how customers can receive the most current upgrade kits.The Hot Line Numbers are: 1-800-755-2345 for U.S. and most of Canada, and 1-480-792-7302 for the rest of the world.
Connecting to the Microchip Internet Web Site
The Microchip web site is available at the following URL: www.microchip.com The file transfer site is available by using an FTP service to connect to: ftp://ftp.microchip.com The web site and file transfer site provide a variety of services. Users may download files for the latest Development Tools, Data Sheets, Application Notes, User's Guides, Articles and Sample Programs. A variety of Microchip specific business information is also available, including listings of Microchip sales offices, distributors and factory representatives. Other data available for consideration is: * Latest Microchip Press Releases * Technical Support Section with Frequently Asked Questions * Design Tips * Device Errata * Job Postings * Microchip Consultant Program Member Listing * Links to other useful web sites related to Microchip Products * Conferences for products, Development Systems, technical information and more * Listing of seminars and events
092002
2003 Microchip Technology Inc.
Preliminary
DS70090A-page 27
rfRXD0420/0920
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150. Please list the following information, and use this outline to provide us with your comments about this document. To: RE: Technical Publications Manager Reader Response Total Pages Sent ________
From: Name Company Address City / State / ZIP / Country Telephone: (_______) _________ - _________ Application (optional): Would you like a reply? Device: rfRXD0420/0920 Questions: 1. What are the best features of this document? Y N Literature Number: DS70090A FAX: (______) _________ - _________
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
DS70090A-page 28
Preliminary
2003 Microchip Technology Inc.
rfRXD0420/0920
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. Device X Temperature Range /XX Package XXX Pattern Examples:
a) b)
Device rfRXD0420-I/LQ UHF ASK/FSK/FM Receiver RFRXD0920-I/LQ UHF ASK/FSK/FM Receiver rfRXD0420T-I/LQ UHF ASK/FSK/FM Receiver (Tape & Reel) RFRXD0920T-I/LQ UHF ASK/FSK/FM Receiver (Tape & Reel) rfRXD0420-I/LQ = Industrial temp, LQFP package RFRXD0920-I/LQ = Industrial temp, LQFP package
Temperature Range
I
=
-40C to +85C
Package
LQ =
LQFP32
Pattern
Special Requirements
Sales and Support
Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. 2. 3. Your local Microchip sales office The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277 The Microchip Worldwide Site (www.microchip.com)
Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
2003 Microchip Technology Inc.
Preliminary
DS70090A-page29
rfRXD0420/0920
NOTES:
DS70090A-page30
Preliminary
2003 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices: * * Microchip products meet the specification contained in their particular Microchip Data Sheet. Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. Microchip is willing to work with the customer who is concerned about the integrity of their code. Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as "unbreakable."
*
* *
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break microchip's code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip's products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights.
Trademarks The Microchip name and logo, the Microchip logo, KEELOQ, MPLAB, PIC, PICmicro, PICSTART, PRO MATE and PowerSmart are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, microID, MXDEV, MXLAB, PICMASTER, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Accuron, dsPIC, dsPICDEM.net, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, microPort, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, PICC, PICkit, PICDEM, PICDEM.net, PowerCal, PowerInfo, PowerTool, rfPIC, Select Mode, SmartSensor, SmartShunt, SmartTel and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. Serialized Quick Turn Programming (SQTP) is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2003, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999 and Mountain View, California in March 2002. The Company's quality system processes and procedures are QS-9000 compliant for its PICmicro(R) 8-bit MCUs, KEELOQ(R) code hopping devices, Serial EEPROMs, microperipherals, non-volatile memory and analog products. In addition, Microchip's quality system for the design and manufacture of development systems is ISO 9001 certified.
2003 Microchip Technology Inc.
Preliminary
DS70090A - page 31
WORLDWIDE SALES AND SERVICE
AMERICAS
Corporate Office
2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: 480-792-7627 Web Address: http://www.microchip.com
ASIA/PACIFIC
Australia
Microchip Technology Australia Pty Ltd Suite 22, 41 Rawson Street Epping 2121, NSW Australia Tel: 61-2-9868-6733 Fax: 61-2-9868-6755
Japan
Microchip Technology Japan K.K. Benex S-1 6F 3-18-20, Shinyokohama Kohoku-Ku, Yokohama-shi Kanagawa, 222-0033, Japan Tel: 81-45-471- 6166 Fax: 81-45-471-6122
Rocky Mountain
2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7966 Fax: 480-792-4338
China - Beijing
Microchip Technology Consulting (Shanghai) Co., Ltd., Beijing Liaison Office Unit 915 Bei Hai Wan Tai Bldg. No. 6 Chaoyangmen Beidajie Beijing, 100027, No. China Tel: 86-10-85282100 Fax: 86-10-85282104
Korea
Microchip Technology Korea 168-1, Youngbo Bldg. 3 Floor Samsung-Dong, Kangnam-Ku Seoul, Korea 135-882 Tel: 82-2-554-7200 Fax: 82-2-558-5934
Atlanta
3780 Mansell Road, Suite 130 Alpharetta, GA 30022 Tel: 770-640-0034 Fax: 770-640-0307
Singapore
Microchip Technology Singapore Pte Ltd. 200 Middle Road #07-02 Prime Centre Singapore, 188980 Tel: 65-6334-8870 Fax: 65-6334-8850
China - Chengdu
Microchip Technology Consulting (Shanghai) Co., Ltd., Chengdu Liaison Office Rm. 2401-2402, 24th Floor, Ming Xing Financial Tower No. 88 TIDU Street Chengdu 610016, China Tel: 86-28-86766200 Fax: 86-28-86766599
Boston
2 Lan Drive, Suite 120 Westford, MA 01886 Tel: 978-692-3848 Fax: 978-692-3821
Taiwan
Microchip Technology (Barbados) Inc., Taiwan Branch 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
Chicago
333 Pierce Road, Suite 180 Itasca, IL 60143 Tel: 630-285-0071 Fax: 630-285-0075
China - Fuzhou
Microchip Technology Consulting (Shanghai) Co., Ltd., Fuzhou Liaison Office Unit 28F, World Trade Plaza No. 71 Wusi Road Fuzhou 350001, China Tel: 86-591-7503506 Fax: 86-591-7503521
Dallas
4570 Westgrove Drive, Suite 160 Addison, TX 75001 Tel: 972-818-7423 Fax: 972-818-2924
EUROPE
Austria
Microchip Technology Austria GmbH Durisolstrasse 2 A-4600 Wels Austria Tel: 43-7242-2244-399 Fax: 43-7242-2244-393
Detroit
Tri-Atria Office Building 32255 Northwestern Highway, Suite 190 Farmington Hills, MI 48334 Tel: 248-538-2250 Fax: 248-538-2260
China - Hong Kong SAR
Microchip Technology Hongkong Ltd. Unit 901-6, Tower 2, Metroplaza 223 Hing Fong Road Kwai Fong, N.T., Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431
Kokomo
2767 S. Albright Road Kokomo, Indiana 46902 Tel: 765-864-8360 Fax: 765-864-8387
Denmark
Microchip Technology Nordic ApS Regus Business Centre Lautrup hoj 1-3 Ballerup DK-2750 Denmark Tel: 45 4420 9895 Fax: 45 4420 9910
China - Shanghai
Microchip Technology Consulting (Shanghai) Co., Ltd. Room 701, Bldg. B Far East International Plaza No. 317 Xian Xia Road Shanghai, 200051 Tel: 86-21-6275-5700 Fax: 86-21-6275-5060
Los Angeles
18201 Von Karman, Suite 1090 Irvine, CA 92612 Tel: 949-263-1888 Fax: 949-263-1338
France
Microchip Technology SARL Parc d'Activite du Moulin de Massy 43 Rue du Saule Trapu Batiment A - ler Etage 91300 Massy, France Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79
San Jose
Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955
China - Shenzhen
Microchip Technology Consulting (Shanghai) Co., Ltd., Shenzhen Liaison Office Rm. 1812, 18/F, Building A, United Plaza No. 5022 Binhe Road, Futian District Shenzhen 518033, China Tel: 86-755-82901380 Fax: 86-755-82966626
Toronto
6285 Northam Drive, Suite 108 Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509
Germany
Microchip Technology GmbH Steinheilstrasse 10 D-85737 Ismaning, Germany Tel: 49-89-627-144 0 Fax: 49-89-627-144-44
China - Qingdao
Rm. B503, Fullhope Plaza, No. 12 Hong Kong Central Rd. Qingdao 266071, China Tel: 86-532-5027355 Fax: 86-532-5027205
Italy
Microchip Technology SRL Centro Direzionale Colleoni Palazzo Taurus 1 V. Le Colleoni 1 20041 Agrate Brianza Milan, Italy Tel: 39-039-65791-1 Fax: 39-039-6899883
India
Microchip Technology Inc. India Liaison Office Divyasree Chambers 1 Floor, Wing A (A3/A4) No. 11, O'Shaugnessey Road Bangalore, 560 025, India Tel: 91-80-2290061 Fax: 91-80-2290062
United Kingdom
Microchip Ltd. 505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44 118 921 5869 Fax: 44-118 921-5820
12/05/02
DS70090A-page 32
Preliminary
2003 Microchip Technology Inc.

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