2014 Power Amplifier Symposium BROADBAND PA TECHNIQUES FOR EFFICIENCY ENHANCEMENT

Transcription

1 14 Power Amlifier Symosium BROADBAND PA TECHNIQUES FOR EFFICIENCY ENHANCEMENT Dr. Andrei Grebennikov 1

2 BROADBAND POWER AMPIFIER TECHNIQUES FOR EFFICIENCY ENHANCEMENT 1.Reactance comensation technique with series and arallel resonant circuits. Broadband arallel-circuit Class-E ower amlifier 3. Fully integrated broadband CMOS Class-E ower amlifier 4. Broadband Class-E ower amlifier with series inductance 5. Broadband arallel Doherty amlifier 6. Inverted Doherty amlifier architecture 7. Broadband inverted GaN HEMT Doherty amlifier

3 1. Reactance comensation technique Reactance comensation load networks with series and arallel resonant circuits ImZ Inut load-network reactance net s 1 C 1 / scs 1/ s (1/ R) 1 C C C To maximize frequency bandwidth: d ImZnet d C 1 R s 1 - reactance rovided by series resonant circuit - reactance rovided by arallel resonant circuit 3 summation of both reactances with oosite sloes Equal loaded quality factors Q C R / R s 3

4 4 Inut load-network admittance 1 Im net d Y d Reactance comensation load networks with arallel and series resonant circuits To maximize frequency bandwidth: 1. Reactance comensation technique s net 1 1 j R j C j Y s s / 1 / 1 C C 1 s R C 1 - suscetance rovided by arallel resonant circuit - suscetance rovided by series resonant circuit 3 summation of both suscetances with oosite sloes Equal loaded quality factors R C R Q / s

5 . Broadband arallel-circuit Class E ower amlifier C C R V cc v t t C R.73 R.685 R P V cc out dv t dt t Otimum circuit arameters: - arallel inductance - shunt caacitance - load resistance: highest value in Class E Inductive imedance at fundamental: R tan 1 RC R 1.6 C 1/ Otimum arameters for series resonant circuit in broadband Class-E mode: 5

6 . Broadband arallel-circuit Class E ower amlifier V Transmission-line arallelcircuit Class-E GaAs HBT ower amlifier for handset alication: 1.75 GHz v c /V cc 3 Collector voltage on off on 3, 8 5, 16 1 F 1 Z net C out 5 F 4 F 5. i c, A t, nsec Collector current Z net ( ) arameters of arallel transmission line is chosen to realize otimum inductive imedance at fundamental 3 1 Z net ( ) Z net (3 ) outut matching circuit consisting of series microstri line with two shunt caacitors should rovide caacitive reactances at second and third harmonics t, nsec Current flowing through collector caacitor 6

7 . Broadband arallel-circuit Class E ower amlifier GHz handset Class-E InGaP/GaAs HBT ower amlifier: two-stage MMIC designed in V 3.5 V V b1 V b Short microstri line P in Bias circuit Bias circuit P out Shunt inductance: bondwire 7

8 . Broadband arallel-circuit Class E ower amlifier GHz handset Class-E InGaP/GaAs HBT ower amlifier: two-stage MMIC designed in 1 Bias circuit Bias circuit P in P out 45 4 Efficiency [%] DCS 18 efficiency PCS 19 efficiency DCS 18 gain PCS 19 gain Gain [db] First device: 54 um Pout [dbm] Second device: 36 um DCS18/PCS19: Pout 3 dbm PAE 51 % Die size:.9 x 1. mm WCDMA at 7 dbm outut ower: ACPR -37 dbc PAE 38 % 8

9 3. Fully integrated broadband CMOS Class-E ower amlifier Enveloe 3.5 V For TE alications:.3-.7 GHz V g f V g1 3.5 V Bias circuit 3f P out High resistivity substrate for high efficiency Bias circuit V dd P in Size: 1.7 x 1.6 mm Simulations:.3 GHz.5 GHz.68 GHz 9

10 3. Fully integrated broadband CMOS Class-E ower amlifier TE test data: 16 QAM, 6.5 dbm,.5 GHz, V dd =.7 V ET disabled ET enabled 35% overall efficiency 41.5% PA efficiency ACR1: 13-dB imrovement ACR: 7-dB imrovement 1

11 4. Broadband Class-E ower amlifier with series inductance Reactance comensation load network with series inductance useful for ackaged devices with series lead inductance shunt inductance and caacitance can be relaced by shortcircuit and oen-circuit stubs at microwaves 11

12 Power gain, db PAE, % 4. Broadband Class-E ower amlifier with series inductance Cree GaN HEMT CGH715P Drain efficiency, % PAE E9 1.7E9 1.9E9.1E9.3E9.5E9.7E9.9E9 Frequency, GHz Outut ower, dbm P out G T E9 1.7E9 1.9E9.1E9.3E9.5E9.7E9.9E9 Frequency, GHz Bandwidth: GHz Drain efficiency = 73% Power gain = 11.8 db Outut ower = 4.8 dbm 1

13 5. Broadband arallel Doherty amlifier Classical Doherty architecture Parallel Doherty architecture P in Carrier PA /4 5 /4 Peaking PA /4 P out 5 P in /4 Peaking PA Carrier PA 5 / /4 7.7 /4 1 1 P out 5 Imedance transformation high-ower region (carrier and eaking PAs are ON): low-ower region (carrier PA is ON and eaking PA is OFF): Imedance transformation high-ower region (carrier and eaking PAs are ON): low-ower region (carrier PA is ON and eaking PA is OFF): 1 5 Imedance transformation ratio = 4 Imedance transformation ratio = oaded quality factor Q oaded quality factor Q

14 5. Broadband arallel Doherty amlifier ow-ower region (eaking amlifier is OFF) Parallel Doherty PA Classical. Magnitude S1 (db) f/f Parallel Classical Doherty PA Half-wave (/4 + /4) line translates oen circuit at eaking amlifier outut to carrier ath 14

15 Drain efficiency, % Drain efficiency, % 5. Broadband arallel Doherty amlifier Parallel Doherty architecture based on broadband Class-E amlifiers with 15-W Cree CGH715P devices: simulation Carrier /4 PA 7.7 /4 15. Power gain Efficiency 8 P in Peaking PA 5 /4 7.7 /4 P out 5 Power gain, db GHz 6 4 Small-signal S Pout, dbm 15 Power gain Efficiency db(s(,1)) Power gain, db GHz Frequency, GHz.-.8 GHz Pout, dbm 15

16 5. Broadband arallel Doherty amlifier Parallel Doherty architecture based on broadband Class-E amlifiers with 15-W Cree CGH715P devices: test board Broadband (-4 GHz) Anaren 3-dB couler dbm SoftPlot Measurement Presentation Uncorrected 38.7dBm Corrected 38.6dBm Start:.75 GHz Sto:.5 GHz Res BW: 3 khz Vid BW: 3 khz Swee:. s 17/1/1 15:11:34 Atten: db FSEA 3 Uncorrected 38.7dBm Measurement Parameter Channel bandwidth Channel sacing On- channel ower Value 1. MHz.14 GHz 6.5 MHz 1-MHz TE dbm signal Adjacent channel ower (channel -1) Adjacent channel ower (channel +1) Adjacent channel ower (channel -) Adjacent channel ower (channel +).73 dbm 3.5 dbm -6.3 dbm dbm Single-carrier 5-MHz WCDMA signal, PAR = 6.5 db: V dd = 8 V P out = 39 dbm Gain = 1 db Drain efficiency = 45% (.14 GHz) 4% (.655 GHz) ACR = -3 dbc -9 dbc 16

17 6. Inverted Doherty amlifier architecture Carrier amlifier Offset lines Inut matching circuit Outut matching circuit Z T, /4 P out Z, /4 P in Inut matching circuit Outut matching circuit Peaking amlifier Short at low ower quarterwave transmission line is connected to outut of eaking amlifier if it is easier to rovide short-circuit condition instead of oen circuit for eaking amlifier in low-ower region offset lines are necessary to comensate for eaking device arasitics and rovide oen-circuit condition seen by carrier amlifying ath in low-ower region required 9 hase shift is rovided in inut circuit of carrier amlifier 17

18 6. Inverted Doherty amlifier architecture carrier device should see high imedance in low-ower region roviding by outut matching circuit -1 X/ZO=. R/ZO=. X/ZO= Z match_off Z ot Гr A Гx CZ match_on Z out_off offset line is necessary to comensate for eaking device arasitics and rovide short-circuit condition at its outut in low-ower region for three-stage inverted Doherty amlifier, drain efficiency of 4% with ower gain of 9 db achieved at 4 dbm (8.5 db backoff) at.14 GHz M.-W. ee, S.-H. Kam, Y.-S. ee, and Y.-H. Jeong, Design of Highly Efficient Three-Stage Inverted Doherty Power Amlifier, IEEE Microwave Wireless Comonents ett., vol. 1, , July 11 18

19 7. Broadband inverted GaN HEMT Doherty amlifier ow-ower region (eaking amlifier is OFF) Inverted Doherty PA Classical. Inverted Magnitude S1 (db) f/f Two-section outut transformer (5 5 ) Quarterwave line translates short circuit at eaking amlifier outut to oen circuit seen by carrier ath and extends bandwidth 19

20 7. Broadband inverted GaN HEMT Doherty amlifier Circuit schematic using two broadband Class-E ower amlifiers for carrier and eaking amlifying aths V gc W = 8.5 mil = 45 mil Substrate: -mil RO436 Carrier Z carrier V dd W = 8.5 mil = 5 mil Two-section outut transformer F 5 W = 1 mil = 4 mil W = 3 mil = mil W = 45 mil = 13 mil 5 F 5 W = 1 mil = 13 mil CGH715F W = 8.5 mil = 3 mil W = 85 mil = 7 mil W = 4 mil = 67 mil P out P in Z eaking W = 8.5 mil = 15 mil F 5 W = 1 mil = 4 mil W = 1 mil = 13 mil W = 3 mil = mil CGH715F W = 8.5 mil = 3 mil W = 45 mil = 13 mil 5 F Z match W = 45 mil = 55 mil Oen circuit in low-ower region W = 8.5 mil = 45 mil Peaking W = 8.5 mil = 5 mil V g V dd

21 7. Broadband inverted GaN HEMT Doherty amlifier Inverted Doherty architecture based on broadband Class-E amlifiers with 15-W Cree CGH715P devices: simulation Inductive imedance at fundamental seen by carrier device in lowower region S(1,1) Z match ow reactance seen at eaking amlifier outut in low-ower region freq (1.8GHz to.7ghz) Z carrier S(1,1) freq (1.8GHz to.7ghz) S(1,1) Z eaking High reactance resented by eaking amlifying ath in low-ower region freq (1.8GHz to.7ghz) 1

22 Drain efficiency (%) 7. Broadband inverted GaN HEMT Doherty amlifier Inverted Doherty architecture based on broadband Class-E amlifiers with 15-W Cree CGH715P devices: simulation Small-signal S db(s(,1)) GHz Frequency, GHz 15. Power gain Efficiency 8 Power gain (db) MHz Outut ower (dbm)

23 7. Broadband inverted GaN HEMT Doherty amlifier Inverted Doherty architecture based on broadband Class-E amlifiers with 15-W Cree CGH715P devices: test board Broadband (69-7 MHz) Anaren 3-dB couler Single-carrier 5-MHz WCDMA signal PAR = 6.5 db: V dd = 8 V P out = 38 dbm Gain = 11 db Drain efficiency = 5% (1.85 GHz) 5% (.15 GHz) 4% (.65 GHz) ACR = -3 dbc -34 dbc -37 dbc 3