TU3B-1. An 81 GHz, 470 mw, 1.1 mm 2 InP HBT Power Amplifier with 4:1 Series Power Combining using Sub-quarter-wavelength Baluns

Transcription

1 TU3B-1 Student Paper Finalist An 81 GHz, 470 mw, 1.1 mm 2 InP HBT Power Amplifier with 4:1 Series Power Combining using Sub-quarter-wavelength Baluns H. Park 1, S. Daneshgar 1, J. C. Rode 1, Z. Griffith 2, M. Urteaga 2, B.S. Kim 3, M. Rodwell 1 1 University of California, Santa Barbara, CA, US 2 Teledyne Scientific and Imaging, Thousand Oaks, CA, US 3 Sungkyunkwan University, Suwon, Republic of Korea

2 Outline Motivation, Challenge Power-combining Techniques in mm-wave Proposed Baluns (2:1 and 4:1 Series Combiners) Power Amplifier Designs (2:1 and 4:1) Measurement Results and Comparisons Conclusion 2

3 mm-wave Power Amplifier: Challenges mm-wave PAs: Applications: High speed communications, high resolution images Needed: High power / High efficiency / Small die area (low cost) Extensive power combining PAE power- combiner drain/ collector 1 1 Gain Compact power-combining Class E/D/F are mm-wave insufficient gain ~f max, high losses in harmonic terminations Efficient power-combining Goal: efficient, compact mm-wave power-combiners 3

4 Parallel Power-Combining Output power: P OUT = V x (M x I) Parallel connection increases P OUT Load Impedance: R OPT = V / (M x I) Parallel connection decreases R OPT High P OUT using low V DD Low R OPT Needs impedance transformation: Wilkinson or lumped lines High insertion loss Small bandwidth Large die area 4

5 Series Power-Combining & Stacks Parallel connections: I OUT = M x I Series connections: V OUT = N x V Output power: P OUT = (N M) x V x I Load impedance: R OPT = (N/M) x V/I Small or zero power-combining losses Small die area BUT, how do we drive the gates? Local voltage feedback: drives gates, sets voltage distribution Design challenge: need uniform RF voltage distribution need ~unity RF current gain per element...needed for simultaneous compression of all FETs. 5

6 Proposed l/4 Baluns Balun structure Simplified model Z stub jz 0,1 2 tan 2 if 2 l/ 4, Zstub Our proposed balun with l/4 lines Three-conductor transmission-lines Two separate transmission lines (m 3 -m 2, m 2 -m 1 ) Fields between m 3 and m 1 isolated! l/4 line stub Z stub = open BUT, still long line high loss and large die area 6

7 Proposed Sub-l/4 Baluns What if balun length is << l/4? Stub line becomes inductive! if 2 l/ 4, Zstub inductive Sub-l/4 balun: Inductive stub line Tunes transistor C OUT!! Short line Low losses Small die area *Symbol: Three-conductor transmission line 7

8 Ideal Tri-axial Line Two separate transmission lines (m 3 -m 2, m 2 -m 1 ) E, H fields between m 3 and m 1 perfectly shielded

9 Baluns in Real ICs 1) M μm 2) M 1 -M 2 Capacitors M 1 -M 2 Line 86 μm 124 μm M 2 91 μm 42 μm HBTs M 1 thickness: 1 μm 3) M 2 -M 3 Line 4) 52 μm M 1 -M 2 gap: 1 μm M 2 thickness: 1 μm M 2 -M 3 Sidewalls 12 μm 10 μm M 2 -M 3 gap: 5 μm M 3 thickness: 3 μm 1) M 1 as a GND 2) Slot-type transmission lines (M 1 -M 2 ), AC short (2 pf MIM) 3) Microstrip line (M 2 -M 3 ), E-field shielding NOT negligible 4) Sidewalls between M 3 -M 1 (Faraday cages), l/16 length 9

10 2:1 Balun B-to-B Test Results v1 v2 C P = 103fF F C = 81GHz I.L. = -1.1dB S21 = -1.76dB C P = 78fF F C = 94GHz I.L. = -1.2dB S21 = -1.79dB Back-to-back measured S-parameters v3 C P = 65fF F C = 103GHz I.L. = -1.2dB S21 = -1.56dB *Does not de-embed losses of PADs, capacitors, and interconnection lines < 0.6dB single-pass insertion loss, 0.16 db/2.7 imbalance 10

11 Teledyne 0.25 μm HBTs Cell: 4-fingers x 0.25 μm x 6 μm BV CEO = 4.5 V, I C,max = 72 ma P OUT = 15.5 dbm R OPT = 56 Ω Emitters to GND MAG/MSG including EM-Sim. results Base Collector f τ =285 GHz, f max =525 J E =4.2 ma/μm 2 and V CE =2.5 V 12~13dB 86 GHz [Z. Griffith et al, IPRM 2012] Multi-finger 250nm InP HBTs for 220GHz mm-wave Power Multi-finger 250nm InP HBTs for 220GHz mm-wave Power 11

12 Sub-l/4 Baluns: PA Design Each HBT loaded by 25 W HBT junction area selected so that I max =V max /25 W Each HBT has some C OUT Stub length picked so that Z stub =-1/jwC OUT tunes HBT P out 2 V 4 max 850W 4:1 more power than without the combiner. 12

13 4:1 PA Designs Using 2:1 Balun Identical input / output baluns 2-section LC input matching network Active bias: Thermal stability & class-ab [H. Park et al, CSICS 2013] 30% PAE W-Band InP Power Amplifiers Using Sub-Quarter-Wavelength Baluns for Series-Connected Power-Combining IC size: 450 x 820 um 2 13

14 Single-Stage PA IC Test Results (86GHz) S-parameters (db) PAE, Gain (%, db) Small signal measurements S11, Measured S11, Simulated S22, Meausred S21, Measured S22, Simulated S21, Simulated Frequency (GHz) Large signal measurements 5 Gain, Measured Gain, Simulated PAE, Measured PAE, Simulated Pout (dbm) Gain: 10 db P SAT : >100 PAE: >30 % 3-dB BW: 23 GHz Power density (power/die area) = 294 mw/mm 2 (including RF pads) = 1210 mw/mm 2 (core area) [H. Park et al, CSICS 2013] 30% PAE W-Band InP Power Amplifiers Using Sub-Quarter-Wavelength Baluns for Series-Connected Power-Combining x4 larger output power than 50 Ohm R OPT device 14

15 Two-Stage PA IC Test Results (86GHz) Large signal measurements PAE, Gain (%, db) Gain, Measured Gain, Simulated PAE, Measured PAE, Simulated Pout (dbm) IC size: 825 x 820 um 2 Gain: 17.5 db P SAT : > V PAE: >30 % Power density (power/die area) = 307 mw/mm 2 (including RF pads) = 927 mw/mm 2 (core area) [H. Park et al, CSICS 2013] 30% PAE W-Band InP Power Amplifiers Using Sub-Quarter-Wavelength Baluns for Series-Connected Power-Combining 15

16 16:1 PA Using 4:1 Baluns 4:1 series-connected power-combining Each HBT loaded by 12.5W HBT junction area selected so that I max =V max /12.5W P out 16 2 V max 850W Each HBT has some C OUT Stub length picked so that Z stub =-1/jwC out tunes HBT 16:1 more power than without combiner. 16

17 PA IC Schematic (2-stages) 2-stage PA using 2:1 and 4:1 baluns 1 st stage 2 nd stage Long lead lines Z load Z load 17

18 PA IC Die Image (2-stages) IC Size: 1.08 x 0.98 mm 2 18

19 PA IC Test Results (81 GHz) Small signal measurements 20 x16 larger output power than 50 Ohm R OPT device S-parameters (db) PAE, Gain (%, db) S21, Measured S21, Simulated S11, Measured S11, Simulated S22, Meausred S22, Simulated Frequency (GHz) Large signal measurements Gain, Measured,2.75V Gain, Simulated,2.75V Gain, Measured,2.45V Gain, Simulated,2.45V PAE, Measured,2.45V PAE, Simulated,2.45V PAE, Measured,2.75V PAE, Simulated,2.75V Pout (dbm) Gain: 17.8dB Output Power: V PAE: 23.4% Power density (power/die area) = 443 mw/mm 2 (including pads) = 1020 mw/mm 2 (only core area) 19

20 mm-wave Power Combiners Ref. Tech. Type N-way Freq. IL Size (GHz) (db) (mm 2 ) This work 0.25 μm Sub-l/4 TL 2:1 InP HBT (60-105) (0.68) 0.03 This work 0.25 μm Sub-l/4 TL :1 InP HBT (ring) (60-110) (0.63) 0.04 This work 0.25 μm Sub-l/4 TL 4:1 InP HBT (75-103) (1.32) Yi 0.13 μm TF 4:1 BiCMOS 77/ * μm TF 8:1 Thian BiCMOS ( ) (0.80 * ) 0.02 # 2010 Chen 65 nm CMOS TF 4: * 0.02 # 2010 Law 90 nm CMOS Wilkinson 2: Zhao 40 nm CMOS Series/ parallel :1 TF (65-90) (1.0) 0.05 # nm CMOS TL 4:1 Niknejad (55-65) (1.25 * ) Liu 0.18 μm CMOS Marchand 2: Hamed InGaP/GaAs Marchand 2:1 (15-45) (1.50) 0.40 * Simulation results, # Area estimated by chip image. IL: insertion loss, TF: transformer, and TL: transmission-line. Parentheses in the frequency and insertion loss columns indicate worst-case insertion loss over the indicated bandwidth. 20

21 mm-wave Power Amplifiers Ref. Tech. f max / f t (GHz) Freq. (GHz) BW (GHz) Max. S 21 (db) P out (dbm) Peak PAE (%) V CC or V DD (V) Size (mm 2 ) mw /mm 2 This 0.25 μm InP HBT work 525 / * 1210 * This 0.25 μm InP HBT work 525 / * 858 * This 0.25 μm InP HBT > Work 525 / * 1020 * μm GaN Brown HEMT > μm GaN Micovic HEMT 230 / Yi 0.13 μm BiCMOS 270 / >10 > nm SOI CMOS Agah * 760 * μm BiCMOS Thian 250 / * 29 * 2010 Chen 65nm CMOS * 256 * 2010 Law 90nm CMOS Zhao 40nm CMOS * 647 * * IC core area (excluding DC feed lines and RF pads), + Value estimated from figure, c) Corporate transmission-line power-combiners, s) Stacked PA. 21

22 Conclusion Sub-l/4 baluns for series-power-combining using a low V BV device Low-loss 2:1 balun, <0.92dB 4:1 balun High power, high efficiency, compact PA IC designs W-band power amplifiers using the 2:1 & 4:1 baluns Record >30 % 100 mw, 200 mw, 23.4 % mw Record 23 GHz 3-dB bandwidth, >10GHz 3-dB BW Record 1210 mw/mm 2 power density, 1020 mw/mm 2 Future directions 220GHz PA designs using the sub-l/4 baluns SiGe PA designs with the optimized balun structures Phased arrays at K/V/E/W bands 22

23 Thanks for your attention! 23