pin diodes for microwave switch designs rev. v2 an3021 1 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. introduction this application note is intended to provide practical gui dance in the selection of pi n diodes for switch control circuit functions. switches, digital and analog attenuators, and limiters ea ch have unique functions that require proper device selection. the design difficulty lies within the parametric translation from diode specifications , to the circuit designers? microwave specifications . diode parametric language such as vb, vf, ct, rs, l , , must convert into insertion loss, vswr, isolation, p1db, input ip3, rf operating power, rf power dissipation, and d.c. power consumption s pecification terminology. in addition to actual diode parameters, pac kage parasitics play a significant role in determining switch circuit per- formance. package capacitance, package inductance, packa ge electrical resistance, and package thermal im- pedance are extremely important considerations to determine the effective frequency bandwidth and maximum incident power for reliable switch operation. the manufacturing methodology dictates the type of di ode selection. surface mount assembly will mandate the usage of either plastic, hmic su rmount, or melf & hipax ceramic devic es. chip and wire ( hybrid ) manu- facturing will determine the us age of cermachips, flip chips, or beam lead devices. schematics for the most common switch designs: series-exclusive, shunt-exclu sive, and series-shunt are outlined below for considera- tion. the decision making process for pin diode selection for microwave switch design the following procedure outlines and effective pr ocess for pin diode selection for switch design. 1. determine the preferred type of manufacturing fo r the pin diode in the switch design: surface mount or chip and wire (hybrid) manufacturing. 2. determine the frequency of operation and rf power handling of the switch design. 3. use table 1, ?relative switch pe rformance and design evaluation matrix ? to determine the type of switch design that best satisfies the particular sw itch specifications and requirements. 4. use table 2, ?relative pin diode performance evaluation matrix ? to determine the type of pin di- ode that best satisfies the switch design selected from table 1. 5. use table 3, ?pin diode p/n series matrix ? to determine the pin diode p/n series that best satis- fies the type of pin diode selected from table 2.
pin diodes for microwave switch designs rev. v2 an3021 2 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. table 1: relative switch performance and design evaluation matrix parameter series diodes exclusive shunt diodes exclusive series-shunt diodes insertion loss worst moderate best vswr moderate worst best isolation worst moderate best p1db moderate moderate moderate input ip3 moderate moderate moderate rf incident power worst best moderate rf power dissipation worst best moderate switching speed worst best moderate d.c. power consumption best (single +5 v) moderate (+5 v, -5 v) worst (+5 v, -5 v) pin diode driver design simplicity best (+5 v only) moderate (+5 v, -5 v) moderate (+5 v, -5 v) rf design simplicity best worst moderate cost best moderate moderate overall evaluation 34 points 38 points 40 points switch design configuration notes: ??? evaluation based upon following grading : best = 5 poin ts, moderate = 3 points, worst = 1 point. the higher the score, the better the overall relative design advantage. ??? where there is no significant relative adv antage, a ? moderate ? weighting can be used. assumptions for sp2t design: ??? design is a reflective sp2t. ??? (2) diodes are used per rf port. ??? frequency bandwidth is 3.0 : 1 maximum. conclusions: the series-shunt design is the best in terms of overall switch performanc e and value. since each design has a specific advantage, the decision for a switch design sele ction is determined by the specific design priorities for the requirement.
pin diodes for microwave switch designs rev. v2 an3021 3 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. table 2: relative pin diode performance evaluation matrix surface mount assembly key parameter plastic melf or hi- pax surmount cerma chip flip chip beam lead 1 mhz < f < 1 ghz best selection 100 mhz < f < 4 ghz best selection 4 ghz < f < 20 ghz best selection 20 ghz < f < 60 ghz best selection best selection 100 mhz < f < 20 ghz best selection pinc < 0.1 w best selection 0.1 w < pinc < 1 w best selection best selection 1 w < pinc < 20 w best selection 20 w < pinc < 200 w best selection best selection relative cost index lowest moderate/hi ghest moderate/highest lowest moderate highest chip & wire hybrid assembly conclusions: 1. plastic devices are best suited where cost is a decision driver, the oper ating frequency < 4 ghz, and the rf c.w. incident power < 1 w ( + 30 dbm ). 2. melf or hipax ceramic devices are best utilized where highest average powe r ( > 20 w c.w. ) is the primary design goal and the operating frequency < 1 ghz. 3. surmount devices are probably the best overall compromise in device selection. they can operate ( in various bands ) from 10 mhz ? 20 ghz and perfor m well with rf incident power < 20 w c.w ( + 43 dbm ). 4. cermachip devices provide the best overall performance for operating frequeny ( 100 mhz ? 20 ghz ) , and rf incident power < 200 w c.w (+ 53 dbm ). 5. flip chip devices are best suited for mmwave frequencies < 60 ghz, where the rf incident c.w. < 1w ( + 30 dbm ) and conductive epoxy or soldering is required. 6. beam lead devices are best suited for mmwave frequencies < 60 ghz, where the rf incident c.w. < 0.1w ( + 20 dbm ) and thermo compression bonding is required.
pin diodes for microwave switch designs rev. v2 an3021 4 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. table 3: pin diode part number series matrix plastic pin diodes melf & hipax pin diodes surmount pin diodes cermachip pin diodes flip chip pin diodes beam lead pin diodes part numbers: ma4p275 series ma4p282 series ma4p789 series ma4p274 series part numbers: ma4p1250 ma4p1450 ma4p4000 series ma4p4300 series ma4p7000 series ma4p7100 series ma4ph23x series part numbers: ma4sps series madp-042xxx series part numbers: MA4P102 ma4p202, 203 ma4p303 ma4p404 ma4p504 ma4p505 ma4p604 ma4p606 ma4pk2000, 3000 part numbers: ma4fpc series ma4agfcp series ma4agsbp series part numbers: ma4pbl series ma4agblp series notes : ??? the following m/a-com pin diode drivers operating with +5 v & -5 v d.c. power supplies are practical with many pin diode switch designs: dr 65 series, madrma0001 and madrma0002 series. ??? m/a-com website homepage hyperlink address: http://www.macom.com
pin diodes for microwave switch designs rev. v2 an3021 5 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. schematic 1: sp2t series exclusive pin diode switch, 40 db isolation with +5 v supply rf series diodes j1 270 +5v j2 +5v 1k sn5406 open collector + 5v ttl driver b2 bias sn5406 open collector + 5v ttl driver +5v 1k j3 b3 bias forward bias diode voltage, vf @ 10 ma ~ + 0.9 v reverse bias diode voltage = - ( +5 v - +2.3 v ) = - 2.7 v schematic 1: d.c. bias to rf truth table rf state b2 bias b3 bias low loss j1-j2 & isolation j1-j3 +0.5 v @ 10 ma +5 v @ 0 ma low loss j1-j3 & isolation j1-j2 +5 v @ 0 ma +0.5 v @ 10 ma
pin diodes for microwave switch designs rev. v2 an3021 6 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. schematic 2: sp2t all shunt, 60 db isolation design with 90 transformer using distributed transmission line j1 j2 j3 b2 b3 = 90 = 90 = 90 = 90 = 90 = 90 = 90 = * l = ( 2 / ) * l, l = /4 = [ 11.807 / ( eff ? * f o * 4 ) ] inches. f o = ( f min * f max ) ? is in ghz, eff is effective dielectric constant of transmission line medium and air. schematic 2: d.c. bias to rf truth table rf state b2 bias b3 bias low loss j1-j2 & isolation j1-j3 -v @ 0 ma +1 v @ (+20 ma per diode) low loss j1-j3 & isolation j1-j2 +1 v @ (+20 ma per diode) -v @ 0 ma
pin diodes for microwave switch designs rev. v2 an3021 7 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. schematic 3: sp2t all shunt, 30 db isolation design using , c-l-c lumped element 90 transformer schematic 3: d.c. bias to rf truth tabl e j3 j2 = 90 deg c c l j1 c c l b2 b3 = 90 deg l = zo / (2 * fo) c = 1 / (2 * fo * zo) fo = (fmin* fmax) 1/2 rf state b2 bias b3 bias low loss j1-j2 & isolation j1-j3 -v @ 0 ma +1 v @ +20 ma low loss j1-j3 & isolation j1-j2 +1 v @ +20 ma -v @ 0 ma
pin diodes for microwave switch designs rev. v2 an3021 8 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. schematic 4: sp2t series-shunt, 40 db isolation design with positive & negative bias current b2 330 ? shunt diode series diode j1 j3 j2 series diode shunt diode b3 schematic 4: d.c. bias to rf truth table rf state b2 bias b3 bias low loss j1-j2 & isolation j1-j3 -4 v @ 10 ma +1 v @ +10 ma low loss j1-j3 & isolation j1-j2 +1 v @ +10 ma -4 v @ -10 ma
pin diodes for microwave switch designs rev. v2 an3021 9 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. schematic 5: sp2t series-shunt, 40 db isolation design with +5 v supply j1 j2 +5v sn7406 open collector + 5v ttl driver +5v b2 series bias j3 330 +5v +5v b3 series bias +5v +5v sn7406 open collector + 5v ttl driver b3 shunt bias b2 shunt bias +5v +5v sn7406 open collector + 5v ttl driver sn7406 open collector + 5v ttl driver +5v b0 voltage 330 330 330 330 schematic 5: d.c. bias to rf truth tabl e rf state b2 series bias b2 shunt bias b3 series bias b3 shunt bias b0 voltage j1-j2 low loss & j1-j3 isolation +0.5 v @ 11 ma +5 v @ 0 ma +1.4 v @ +11 ma (to j3 shunt diode) +0.5 v @ +11 ma +1.4 v j1-j3 low loss & j1-j2 isolation +1.4 v @ +11 ma (to j2 shunt diode) +0.5 v @ +11 ma +0.5 v @ +10 ma +5 v @ 0 ma +1.4 v notes: 1. forward bias diode ? vf @ 10 ma ~ +0.9 v 2. reverse bias series diode = (+1.4 v - +1.4 v) = 0 v 3. reverse bias shunt diode = (+0.5 v - +5.0 v) = -4.5 v
pin diodes for microwave switch designs rev. v2 an3021 10 advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 visit www.macomtech.com for addi tional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. schematic 6: tr switch schematic with 25 db isolation design with +3 v supply ant rx tx = 90 @ fo c c l b1 bias schematic 6: tr switch d.c. bias to rf truth table rf state b1 bias low loss tx - ant & isolation rx - tx +2 v @ +10 ma low loss ant - rx & isolation tx - rx 0 v @ 0 ma for lumped electrical transmission line length, , between junction and rx shunt diode : l = zo/ (2 fo) , c = 1/ (2 fo zo) , where fo is the resonant frequency = ( f 1 * f 2 ) ? & f 1 & f 2 are band edge frequencies .
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