High Frequency Power Amplifiers V Paidi Department of

High Frequency Power Amplifiers V. Paidi Department of Electrical and Computer Engineering, University of California, Santa Barbara Slide 1

Outline • • Research to date • Class B Power amplifiers in Ga. N HEMT technology for applications in X-band. • Design of G-band (140 -220 GHz) Power Amplifiers in In. P mesa DHBT technology. Proposed Future Research • Fabrication and measurement of G-band ( 140 -220 GHz) Power amplifiers in In. P DHBT technology • Process improvements for better yield and performance. Slide 2

Class B Power amplifiers in Ga. N HEMT technology • Push-Pull Vs Single-ended topology. • Common Source Class B. • Common Drain Class B. Slide 3

Why Class B? and Why Ga. N HEMTs? • Why Class B ? – Class A: Ideal PAE 50%, feasible PAE 20 -30%. However , good linearity. – Switch mode Amplifiers: Ideal PAE 100%, feasible PAE 60 -70 %. Poor Linearity. – Class B: Ideal PAE 78. 6%; feasible PAE 40 -50% (typical Ga. N HEMT at X-band). Potential Low distortion Operation. • Why Ga. N HEMTs ? – Excellent Power density, as high as 12 W/mm in X-band. – ft ~ 50 GHz and fmax ~ 80 GHz for Lg ~ 0. 25 m due to high saturation velocity. – ‘Near Linear’ Id-Vgs Characteristics about threshold leading to a potential Slide 4 low distortion Class B operation.

Push-pull Class B UCSB V. Paidi, S. Xie • Half sinusoidal drain current on each device, but full sinusoidal drain voltage. • Even harmonics are suppressed by symmetry => wide bandwidth (limited by the power combiner). • To obtain high efficiency (78%), a half-sinusoidal current is needed at each drain. This requires an even-harmonic short. This can be achieved at HF/VHF frequencies with transformers or bandpass filters. However, 1. Most wideband microwave baluns can not provide effective broadband short for even-mode. Efficiency is then poor. 2. They occupy a lot of expensive die area on MMIC. Slide 5

Single-ended Class B = push-pull UCSB V. Paidi, S. Xie Push-pull Class B Even harmonics suppressed by symmetry Single-ended Class B with an output filter harmonic + IMD distortion Only harmonic distortion Even harmonics suppressed by filter. Bandwidth restriction < 2: 1 Slide 6

Linearity Analysis-Id vs Vgs UCSB V. Paidi, S. Xie Near linear characteristics of Ga. N HEMTs on Si. C Odd-part creates distortion The third order term is small about the threshold Voltage Slide 7

Linearity Analysis-Id vs Vgs Contd. Class B bias has the minimum distortion Slide 8 UCSB V. Paidi, S. Xie

Process and Device Performance Pulsed IV Curve(80 sec) 600 m Single gate Ga. N HEMT Good Passivation, 600 m. A at Vgs=0 V UCSB V. Paidi, S. Xie • Lg ~ 0. 25 um, Idss ~ 1 A/mm • ft ~ 55 GHz (~ 50 GHz for dual gate) • Vbr ~ 40 V (~ 55 V for dual gate) RF Performance at Vds=15 V, Vgs= -3. 5 V of 0. 25 X 150 m 2 device ~1. 2 A f. T~50 GHz Slide 9

Single-ended Class B Power Amplifier Lossy input matching S. Xie, V. Paidi - section lowpass filter Slide 10 UCSB

Class B bias @Vgs = - 5. 1 V UCSB V. Paidi, S. Xie Single tone performance @ f 0 = 8 GHz: Saturated output power 36 d. Bm Gain ~ 13 d. B, PAE (maximum) ~ 34% f 1, f 2 Two tone performance @ f 1=8 GHz, f 2=8. 001 GHz : 2 f 1 -f 2, 2 f 2 -f 1 Good IM 3 performance: • 40 d. Bc at Pin = 15 d. Bm, and • > 35 d. Bc for Pin < 17. 5 d. Bm Slide 11

UCSB Summary of IM 3 suppression Class B V. Paidi, S. Xie Class AB Psat Class C • • • Low output power levels (Pout < 24 d. Bm), Class A and Class B both exhibit good linearity (Class B > 36 d. Bc, Class A > 45 d. Bc). Higher output power levels, Class A behaves almost the same as Class B. Slide 12 Class AB and C exhibit more distortion compared to

Why Common Drain Class B ? Circuit Schematic UCSB V. Paidi, S. Xie Gain of the Common Drain Class B Gain of the Common Source Class B In Common drain design the nonlinearity in gm is suppressed by the feedback term in the denominator. If , then voltage Gain is independent of gm Disadvantage : Maximum stable gain is less for common dr configuration resulting in reduction in efficienc With higher fmax MSG could be better. Slide 13

Comparison between Common Drain UCSB V. Paidi, S. Xie and Common source designs • Common drain and common source designs are @ 10 GHz Common Drain 12 d. B Common Source • Both have 36 d. Bm of saturated output power. 1. 2 mm Ga. N HEMTs are used. • Common drain design has ~12 d. B superior IM 3 suppression over the equivalent Common Source design. • At 1 W total output power Common drain exhibits 46 d. Bc IMD 3 Common source exhibits 36 d. Bc IMD 3. Slide 14

UCSB Common Drain Class B Power Amplifier V. Paidi, S. Xie Layout ~6 mm X 2. 5 mm Specifications • 37 d. Bm saturated output power at 5 GHz • 8 d. B Class B gain, 4 -6 GHz bandwidth. • 38% maximum PAE • 44 d. Bc at 1 W total output power under Class B bias. • Being fabricated by Shouxuan Xie IMD 3 > 42 d. Bc for Pout <2 W Psat ~ 37 dbm PAE ~ 38 % Slide 15

Power Amplifiers in In. P mesa DHBT technology • Motivation. • Layer Structure and process ( Mattias, Zach ). • Performance of In. P mesa DHBT technology ( Mattias, Zach). • G-band ( 140 -220 GHz) Power amplifier design and layout. Slide 16

Motivation for 140 - 220 GHz power amplifiers and Previous results • Applications for electronics in 140 -220 GHz frequency band Wideband communication systems Atmospheric sensing Automotive radar • Small signal amplifier results 6. 3 d. B @ 175 GHz single stage amplifier in In. P TSHBT technology, Miguel et. al. , 12 d. B @ 170 GHz three stage CE amplifier in In. P TSHBT technology, Miguel et. al. , 3 -stage amplifier with 12 -15 d. B gain from 160 -190 GHz, In. P HEMT, Lai et. al. 6 -stage amplifier with 20 6 d. B from 150 -215 GHz, In. P HEMT, Weinreb et. al. • Power amplifier results 12. 5 d. Bm @90 GHz with 8. 6 d. B gain in TS In. P DHBT technology, Yun et. Slide 17 al. ,

Why mesa -In. P HBTs for 140 - 220 GHz power amplifiers ? • fmax > 400 GHz for 2100 A Collector, 300 A base HBT ( Technologies like Si. Ge have fmax ~ 210 GHz Jae- Sung Rieh et al. , IBM ( IPRM 2003) ) • High bandwidth as ft > 250 GHz for 2100 A Collector, 300 A base HBT • Current density > 3 m. A/ m 2 at Vbe = 0. 7 V and Vcb = 0 V for Tc = 2100 A. • Vbr, ce 0 > 6 V • Low thermal resistance. Slide 18

Layer Structure Material Doping (cm 3) Thickness ( ) n-In. Ga. As 3∙ 1019 300 n-In. P 3∙ 1019 1000 n-In. P 8∙ 1017 100 n-In. P 5∙ 1017 500 p+-In. Ga. As 5 -8∙ 1019 (C) 350 n-In. Ga. As 1. 5∙ 1016 200 Base Collector Grade 1. 5∙ 1016 240 n-In. P 3∙ 1018 30 n-In. P 1. 5∙ 1016 1630 n+-In. P 1. 5∙ 1019 100 n+-In. Ga. As 2∙ 1019 100 n+-In. P 2∙ 1019 UCSB Mattias, Zach In. P Emitter n+ doped P+ In. Ga. As Base: doping grading 2100 Å n- In. P Collector 3000 Slide 19

Mesa IC Process: Key Features Slide 1 Slide 20

Mesa IC Process: Key Features Slide 2 Slide 21

Mesa IC Process: Key Features Slide 3 Slide 22

Mesa IC Process: Key Features Slide 4 Slide 23

Mesa IC Process: Key Features Slide 5 Slide 24

Mesa IC Process: Key Features Slide 6 Slide 25

Mesa IC Process: Key Features Slide 7 Slide 26

Mesa IC Process: overview • Both junctions defined by selective wet-etch chemistry • Narrow base mesa allows for low AC to AE ratio • Low base contact resistance— Pd based ohmics with C < 10 -7 ∙cm 2 • CPW wiring environment…. • Collector contact metal and metal ‘ 1’ used as interconnect metal • Ni. Cr thin film resistors = 40 / • MIM capacitor, with Si. N Slide 27 dielectric… -- used only for • has predictable characteristic impedance • CPWs are modeled using ADS momentum • Air bridges are used to strap the ground planes

DC and RF measurements UCSB Mattias, Zach • Common emitter characteristics • Device geometry: emitter metal = 0. 6 8. 0 m 2, real device = 0. 54 ∙ 7. 7 m 2 • Collector to emitter area ratio, AC / AE = 5 • IB = 50 A per step • DC beta = 20 • Vbr = 7 V • f = 282 GHz, fmax = 400 GHz • Measurement condition: VCE = 1. 7 Volts, Jc = 3. 6 m. A/ m 2 Slide 28

Thermal considerations • Device geometry: emitter metal = 0. 8 12. 0 m 2 • Vbr = 7 V, Imax = 3 m. A/ m 2. • θ = 1. 25 K/ m. W. ( Dr. Ian Harrison’s simulations) th • Bias conditions, VCE = 3. 5 V, IC = 13 m. A (1. 5 m. A/ m 2). • The device is thermally stable even without external ballast resistance • However, improvements in Rex could be dangerous. • Few backup designs with ballast resistance are included. Slide 29

Single stage Common Base G band ( 140 - 220 GHz) power amplifier in In. P DHBT technology common base PA Objectives: G band, Psat~ 20 d. Bm Approach: In. P mesa-DHBTs, microwave amplifier design Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0=180 GHz, BW 3 d. B ~ 45 GHz, GT=5. 3 d. B, Psat ~ 20 d. Bm. 2 x 2 x 0. 8 m x 12 m, AE=38 m 2 Slide 30

Two stage Common Base G band ( 140 -220 GHz) power amplifier in In. P DHBT technology common base PA Objectives: G band, Psat~ 19. 5 d. Bm Approach: In. P mesa-DHBTs, microwave amplifier design Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0=180 GHz, BW 3 d. B ~ 45 GHz, GT=8. 7 d. B, Psat ~ 19. 5 d. Bm. 6 x 0. 8 m x 12 m, AE=58 m 2 Slide 31

Cascode G band ( 140 -220 GHz) power amplifier in In. P DHBT technology Cascode PA Objectives: G band, Psat~ 16. 5 d. Bm Approach: In. P mesa-DHBTs, microwave amplifier design Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0=180 GHz, BW 3 d. B ~ 45 GHz, GT=8. 5 d. B, Psat ~ 16. 5 d. Bm. 4 x 0. 8 m x 12 m, AE=38 mm 2 Slide 32

Two stage Common Base G band ( 140 - 220 GHz) power amplifier With Emitter ballasting Resistance Objectives: G band, P common base PA sat~ 16. 5 d. Bm Approach: In. P mesa-DHBTs, microwave amplifier design, 1Ώ per each finger, ~ 20 Ώ / m 2 Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0=180 GHz, BW 3 d. B ~ 45 GHz, GT=8 d. B, Psat ~ 16. 5 d. Bm. 4 x 0. 8 m x 12 m, AE=38 m 2 Slide 33

Single stage Common Base W band ( 75 -110 GHz) Power Amplifier Objectives: W band, Psat~ 20 d. Bm common base PA Approach: In. P mesa-DHBTs, microwave amplifier design, Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0=100 GHz, BW 3 d. B ~ 45 GHz, GT=8 d. B, Psat ~ 20 d. Bm. 4 x 0. 8 m x 12 m, AE=38 m 2 Slide 34

Summary of All Designs The mask has • 0 - 50 GHz : One Single Stage 100 m. W design • 50 – 70 GHz : One Single Stage 100 m. W design • 70 - 110 GHz : Three Single Stage 100 m. W designs • 110 – 140 GHz : Two Single Stage 100 m. W designs, One Cascode 50 m. W design • 140 – 220 GHz : Eight Single Stage 50 m. W designs, Four Single Stage 100 m. W designs, Six Two Stage 50 m. W designs, Two Stage 100 m. W designs, Four Cascode 50 m. W designs • RF Calibration Structures Slide 35

Accomplishments • Successful fabrication of X-band Class B Power amplifier in Ga. N HEMT technology for good linearity and efficiency. • Design of Common Drain Class B for further linearity enhancement. ( Currently being fabricated by Shouxuan Xie) • Design of G – band ( 140 -220 GHz) power amplifiers in In. P mesa DHBT technology. Slide 36

Proposed Work • Fabrication of the power amplifiers in UCSB In. P mesa DHBT process. • Testing and measurement in collaboration with Jet Propulsion Labs. • Improve the In. P mesa process for better yield and performance. • More iterations to improve the amplifier performance. Slide 37

Acknowledgements This work was supported by the ONR , JPL , DARPA. Slide 38

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What does JPL have? • Till 110 GHz we have measurement set up • Several 160 - 200 GHz Schottky diode amps Psat ~ 50 m. W ( Lorene) • 140, 180 doublers and triplers and power heads. ( Lorene ) • JPL has sources and power heads from 40 -120 GHz ( Lorene) Slide 41

Simulations of Class B Simulation of class B amplifier @10 GHz UCSB S. Xie, V. Paidi Waveforms of drain voltage and current Saturated output power ~37 d. Bm Saturated PAE ~48% Class B bias: Saturated output power ~ 37 d. Bm, Saturated PAE ~ 48% Slide 42

Simulations of Class B Contd. Class B bias: C/IMD 3~44 d. Bc PAE ~ 48% UCSB S. Xie, V. Paidi Class A bias C/IMD 3~42 d. Bc PAE ~ 35% Class AB bias Class C bias Best IM 3 suppression is achieved at Class B and Class A Slide 43

Measurement setup UCSB V. Paidi, S. Xie Measurements: • Single tone from 4 GHz to 12 GHz; • Two-tone measurement at f 1 = 8 GHz, f 2 = 8. 001 GHz; • Bias sweep: Class A (Vgs = -3. 1 V), Class B (Vgs = -5. 1 V, Class C (Vgs = - 5. 5 V) and AB (Vgs = -4. 5 V). Slide 44

Class B vs. Class A PAE of single tone UCSB V. Paidi, S. Xie IM 3 suppression and PAE of two-tone Class A Class B Maintaining good IM 3 suppression Class B can get 10% PAE improvement over Class A during low distortion operation. Slide 45

Class A bias @Vgs = - 3. 1 V UCSB V. Paidi, S. Xie Single tone performance @ f 0 = 8 GHz: Saturated output power 36 d. Bm PAE (maximum) ~ 34% f 1, f 2 Two tone performance @ f 1=8 GHz, and f 2=8. 001 GHz : Saturated output power each tone ~ 33 d. Bm 2 f 1 -f 2, 2 f 2 -f 1 Good IM 3 performance at low power level but becomes bad rapidly at high power levels Slide 46

Linearity Analysis-Cgs vs Vgs UCSB V. Paidi, S. Xie Anti-symmetric Cgs vs Vgs characteristics of Ga. N HEMTs on Si. C Even-part creates distortion C 2 is small due to the anti-symmetric Cgs vs Vgs Slide 47

Linearity Analysis-Cgs vs Vgs Contd. Class B bias has low distortion Slide 48 UCSB V. Paidi, S. Xie

Measured Gain vs. frequency Class AB Class B 3 d. B bandwidth: 7 GHz - 10 GHz Slide 49 UCSB S. Xie, V. Paidi

UCSB Summary of All Designs Design Topology paidi f 0, GHz Area( m 2) Psat, d. Bm Gain BW 3 d. B Common Base, Single Stage 40 4 x 0. 8 x 12 20 d. Bm 10 d. B 30 GHz Common Base, Single Stage 60 4 x 0. 8 x 12 20 d. Bm 10 d. B 35 GHz Common Base, Single Stage 80 4 x 0. 8 x 12 20 d. Bm 10 d. B 35 GHz Common Base, Single Stage 100 4 x 0. 8 x 12 20 d. Bm 8 d. B 45 GHz Common Base, Single Stage 120 4 x 0. 8 x 12 20 d. Bm 7. 5 d. B 55 GHz Common Base, Single Stage 140 2 x 0. 8 x 12 16. 5 d. Bm 8. 3 d. B 40 GHz Common Base, Single Stage 160 2 x 0. 8 x 12 16. 5 d. Bm 7. 5 d. B 40 GHz Common Base, Single Stage 180 Slide 50 2 x 0. 8 x 12 16. 5 d. Bm 5. 6 d. B 55 GHz

UCSB Summary of All Designs Design Topology paidi f 0, GHz Area( m 2) Psat, d. Bm Gain Common Base Single Stage 160 2 x 0. 8 x 20 d. Bm 7. 1 d. B 45 12 GHz Common Base Single Stage 180 2 x 0. 8 x 20 d. Bm 5. 4 d. B 55 12 GHz Common Base Single Stage 200 2 x 0. 8 x 19 d. Bm 4. 7 d. B 60 12 GHz Common Base Single Stage (no cap) 100 4 x 0. 8 x 12 20 d. Bm 9 d. B 30 GHz Common Base Single Stage (no cap) 120 4 x 0. 8 x 12 20 d. Bm 7 d. B 30 GHz Common Base Single Stage (no cap) 140 2 x 0. 8 x 12 17 d. Bm 7 d. B 55 GHz Common Base Single Stage (no cap) 180 2 x 0. 8 x 12 17 d. Bm 5. 3 d. B 40 GHz Common Base Single Stage 200 2 x 0. 8 x 12 Slide 51 16 d. Bm 4 d. B BW 3 d. B 70

UCSB Summary of All Designs Design Topology paidi f 0, GHz Area( m 2) Psat, d. Bm Gain Common Base Two Stage 180 6 x 0. 8 x 12 19. 5 d. Bm 8. 6 d. B 45 GHz Common Base Two Stage 200 4 x 0. 8 x 12 17 d. Bm 10 d. B 50 GHz Common Base Two Stage ( no 180 cap) 4 x 0. 8 x 12 17 d. Bm 10. 5 d. B 45 GHz Common Base Two Stage ( no 180 cap) Ballast resistance 20 ohm m 2 4 x 0. 8 x 12 17 d. Bm 8. 6 d. B 50 GHz Common Base Two Stage ( no 180 cap) Ballast resistance 40 ohm m 2 4 x 0. 8 x 12 17 d. Bm 7. 2 d. B 50 GHz Cascode 120 4 x 0. 8 x 12 17 d. Bm 13 d. B 35 GHz Cascode 140 4 x 0. 8 x 12 17 d. Bm 8 d. B 110 GH z Slide 52 BW 3 d. B

Conclusions UCSB S. Xie, V. Paidi • For less than octave bandwidth, push-pull and single -ended Class B amplifiers have equivalent PAE and linearity. • A single-ended Class B MMIC power amplifier in Ga. N HEMT technology is designed and 36 d. Bm of saturated power and 35 d. Bc of IM 3 suppression are obtained. • Class B is better than Class A because it can get good IM 3 performance comparable to that of Class A, while providing more than 10% improvement in PAE under low distortion operation. Slide 53

Chip photograph of Class B power amplifier Gate 1 UCSB V. Paidi, S. Xie Gate 2 Source Air bridges Drain (Approximately 6 mm. X 1. 5 mm) Slide 54

Comparison between Common Drain UCSB and Common source designs Contd. V. Paidi, S. Xie IM 3 suppression at 1 W total output power as a function of bias point Class C Common Drain Class AB Common source Class B Slide 55 Class A

UCSB Common Drain Class B Power Amplifier V. Paidi, S. Xie Specifications • 37 d. Bm saturated output power at 5 GHz • 8 d. B Class B gain, 4 -6 GHz bandwidth. • 38% maximum PAE • 44 d. Bc at 1 W total output power under Class B bias. Layout ~6 mm X 2. 5 mm Slide 56

How does push-pull Class B PA work? UCSB V. Paidi, S. Xie VDS 1 +Vin 0 180 • • 0 -Vin VDS 2 Vout = VDS 1 – VDS 2 Two identical devices working in 50% duty cycle with 180° phase shift. Half sinusoidal drain current on each device, but full sinusoidal drain voltage. Even harmonics are suppressed by symmetry => wide bandwidth (limited by the power combiner). Class B: Ideal PAE 78. 6%; feasible PAE 40 -50% (typical Ga. N HEMT at Xband); Class A: Ideal PAE 50%, feasible PAE 20 -30%. Slide 57

Common Base Power Amplifier @40 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 21 d. Bm Approximate Layout (1. 1 mm X 0. 3 mm) Performance gain > 10 d. B Slide 58

Common Base Power Amplifier @60 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout > 21 d. Bm Approximate Layout (0. 7 mm X 0. 3 mm) Performance gain > 10 d. B Slide 59

Common Base Power Amplifier @80 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout > 21 d. Bm Approximate Layout (0. 6 mm X 0. 3 mm) Performance gain > 10 d. B Slide 60

Common Base Power Amplifier @100 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout > 20 d. Bm Approximate Layout (0. 5 mm X 0. 3 mm) Performance gain > 8 d. B Slide 61

Common Base Power Amplifier @120 GHz Pout > 20 d. Bm Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Approximate Layout (0. 5 mm X 0. 3 mm) Performance gain > 7 d. B Slide 62

Common Base Power Amplifier @140 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout > 16 d. Bm Approximate Layout (0. 5 mm X 0. 3 mm) Performance gain > 8 d. B Slide 63

Common Base Power Amplifier @160 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout > 16 d. Bm Approximate Layout (0. 4 mm X 0. 3 mm) Performance gain > 8 d. B Slide 64

Common Base Power Amplifier @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout > 16 d. Bm Approximate Layout (0. 4 mm X 0. 3 mm) Performance gain ~ 5 d. B Slide 65

Common Base Power Amplifier @200 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout ~ 16 d. Bm Approximate Layout (0. 4 mm X 0. 3 mm) Performance gain ~ 5 d. B Slide 66

Common Base Power Amplifier @220 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout ~ 15 d. Bm Approximate Layout (0. 3 mm X 0. 3 mm) Performance gain ~ 5 d. B Slide 67

Common Base Power Amplifier @140 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 20 d. Bm Approximate Layout (0. 7 mm X 0. 6 mm) Performance gain ~ 7. 5 d. B Slide 68

Common Base Power Amplifier @160 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 20 d. Bm Approximate Layout (0. 6 mm X 0. 5 mm) Performance gain ~ 6. 8 d. B Slide 69

Common Base Power Amplifier @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 20 d. Bm Approximate Layout (0. 5 mm X 0. 5 mm) Performance gain ~ 5 d. B Slide 70

Common Base Power Amplifier @200 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 19 d. Bm Approximate Layout (0. 5 mm X 0. 5 mm) Performance gain ~ 4. 5 d. B Slide 71

Two-stage Common Base Power Amplifier @140 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 16 d. Bm Approximate Layout (1 mm X 0. 7 mm) Performance gain ~ 15 d. B Slide 72

Two-stage Common Base Power Amplifier @140 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~6 fingers. X 0. 8 X 12 um 2 Pout ~ 20 d. Bm Approximate Layout (1. 3 mm X 0. 7 mm) Performance gain ~ 15 d. B Slide 73

Two-stage Common Base Power Amplifier @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 16. 5 d. Bm Approximate Layout (1. 3 mm X 0. 7 mm) Performance gain ~ 10 d. B Slide 74

Two-stage Common Base Power Amplifier @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~6 fingers. X 0. 8 X 12 um 2 Pout ~ 20 d. Bm Approximate Layout (1. 3 mm X 0. 7 mm) Performance gain ~ 8. 5 d. B Slide 75

Two-stage Common Base Power Amplifier @200 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 16. 5 d. Bm Approximate Layout (1. 3 mm X 0. 7 mm) Performance gain ~ 10 d. B Slide 76

Cascode Power Amplifier @140 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout > 17 d. Bm Approximate Layout (0. 5 mm X 0. 6 mm) Performance gain ~ 8 d. B Slide 77

Cascode Power Amplifier @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 16. 5 d. Bm Approximate Layout (0. 5 mm X 0. 6 mm) Performance gain ~ 8 d. B Slide 78

Common Base Power Amplifier (No Cap design) @100 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout ~ 19 d. Bm Approximate Layout (0. 5 mm X 0. 3 mm) Performance gain ~ 8 d. B Slide 79

Common Base Power Amplifier (No Cap design) @140 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout ~ 15. 5 d. Bm Approximate Layout (0. 5 mm X 0. 3 mm) Performance gain ~ 7 d. B Slide 80

Common Base Power Amplifier (No Cap design) @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout ~ 16 d. Bm Approximate Layout (0. 3 mm X 0. 3 mm) Performance gain ~ 5 d. B Slide 81

Common Base Power Amplifier (No Cap design) @200 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~2 fingers. X 0. 8 X 12 um 2 Pout ~ 16 d. Bm Approximate Layout (0. 3 mm X 0. 3 mm) Performance gain ~ 4 d. B Slide 82

Two-stage Common Base Power Amplifier (No Cap design) @180 GHz Technology: • In. P mesa HBT • Ft~200 GHz, fmax ~400 GHz • Vbr ~ 7 V • Current density ~ 3 m. A/um 2 • Area ~4 fingers. X 0. 8 X 12 um 2 Pout > 16 d. Bm Approximate Layout (0. 3 mm X 0. 3 mm) Performance gain ~ 10 d. B Slide 83

Thermal Structures--- 18 um gate length device with three partitions 0, 4, 8 Slide 84

Thermal Structures --- 2 finger device with 0, 4, 8 ballasting(0. 8 X 12) Slide 85

Ga. N HEMT Model Slide 86

Ga. N HEMT Model Contd. -Gm block Variables ---- gm, ft, vp, fudfactor(0. 05 here) ---- automatic Gds modeling. Probably more accurate. Slide 87

Ga. N HEMT Model Contd. -Gm block a discussion The Id-Vds characteristics do not show any change Of pinch-off voltage till Vds ~ 7 -10 V. Then there would Be a shift of 0. 5 -1 V per every 10 V Vds increase. This has been more accurately modeled in this new Device model. Slide 88

Ga. N HEMT Model Contd. -Gm block a discussion The Id-Vds characteristics of a 1. 2 mm device. Slide 89

Ga. N HEMT Model Contd. -Gm block a discussion The Id-Vgs characteristics of a 1. 2 mm device at Vds= 15 V. Slide 90

Ga. N HEMT Model Contd. -Cgs Slide 91

Ga. N HEMT Model Contd. -Cgs The Id-Vgs characteristics of a 1. 2 mm device at Vds= 15 V. Slide 92

Ga. N HEMT Model Contd. -Cgs The S-parameter match of SG device at -4 V Vgs, 20 V Vds Model could be fine tuned. But my point is that this model is Not way off. Slide 93

Dual Gate device and linearity concerns. The Common Source Power Amplifier Circuit: Slide 94

Dual Gate device and linearity concerns. model: Slide 95

Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity model: Slide 96

Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity Biased at Class B -6 V here: Slide 97

Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity Biased at Class C -7 V here: Slide 98

Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity Biased at Class AB -4. 5 V here: Slide 99

Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity Biased at Class A -3 V here: Slide 100

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity model: Slide 101

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity Biased at Class B -6 V: Slide 102

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity Biased at Class C -7 V: Slide 103

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity Biased at Class AB -4. 5 V: Slide 104

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity Biased at Class AB -3 V: Slide 105

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs+Vp shift non-linearity model: Slide 106

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs+Vp shift non-linearity Class B -6. 1 V The rest does not change that much: Slide 107

Single Gate device and linearity concerns. Common source Circuit Design Slide 108

Single Gate device and linearity concerns. Common drain Circuit Design Slide 109

Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Model: Slide 110

Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Class B -6 V: Slide 111

Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Class C -7 V: Slide 112

Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Class AB -4. 5 V: Slide 113

Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Class A -3 V: Slide 114

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity model: Slide 115

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity Class B -6 V: Slide 116

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity Class C -7 V: Slide 117

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity Class AB -4. 5 V: Slide 118

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity Class AB -3 V: Slide 119

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity model: Slide 120

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class B -6. 5 V: Slide 121

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class C -7. 5 V: Slide 122

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class AB -4. 5 V: Slide 123

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class A -3 V: Slide 124

Common Drain Circuit on chip right now! Circuit Diagram (slightly modified): Slide 125

Common Drain Circuit on chip right now! Class B -6. 5 V Slide 126

Common Drain Circuit on chip right now! Class C -7. 5 V Slide 127

Common Drain Circuit on chip right now! Class AB -4. 5 V Slide 128

Common Drain Circuit on chip right now! Class A -3 V Slide 129

Common Drain Circuit on chip right now! Class B -6. 5 V--- Two tone simulation Slide 130

Class B two-tone output spectrum Medium input power 1 Low input power Pout =18 d. Bm Pout = 4 d. Bm IM 3 = 39 d. Bc IM 3 = 43 d. Bc Medium input power 2 High input power Pout = 22 d. Bm IM 3 = 40 d. Bc Slide 131 Pout = 26 d. Bm IM 3 = 25 d. Bc

Class A two-tone output spectrum Low input power Medium input power 2 Pout = 10 d. Bm Pout = 23 d. Bm IM 3 > 50 d. Bc IM 3 = 42 d. Bc Medium input power 2 High input power Pout = 27 d. Bm IM 3 = 31 d. Bc Pout = 31 d. Bm IM 3 = 15 d. Bc Slide 132