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

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

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

Class B Power amplifiers in GaN HEMT technology Push-Pull Vs Single-ended topology. Common Source Class B. Common Drain Class B.

Why Class B? and Why GaN 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 GaN HEMT at X-band). Potential Low distortion Operation. Why GaN HEMTs ? –Excellent Power density, as high as 12 W/mm in X-band. –f t ~ 50 GHz and f max ~ 80 GHz for Lg ~ 0.25  m due to high saturation velocity. – ‘ Near Linear’ I d -V gs Characteristics about threshold leading to a potential low distortion Class B operation.

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. UCSB Push-pull Class B V. Paidi, S. Xie

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

UCSB Linearity Analysis-I d vs V gs V. Paidi, S. Xie Near linear characteristics of GaN HEMTs on SiC The third order term is small about the threshold Voltage Odd-part creates distortion

UCSB Linearity Analysis-I d vs V gs Contd. V. Paidi, S. Xie Class B bias has the minimum distortion

RF Performance at Vds=15V, Vgs=-3.5V of 0.25X150  m 2 device Process and Device Performance L g ~ 0.25um,Idss ~ 1A/mm ft ~ 55 GHz (~ 50 GHz for dual gate) Vbr ~ 40V (~ 55V for dual gate) Pulsed IV Curve(80  sec) 600  m Single gate GaN HEMT ~1.2 A Good Passivation, 600mA at Vgs=0V f T ~50 GHz UCSB V. Paidi, S. Xie

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

Class B bias @Vgs = - 5.1V Single tone performance @ f 0 = 8GHz: Two tone performance @ f 1 =8GHz, f 2 =8.001GHz : f 1,f 2 2f 1 -f 2, 2f 2 -f 1 Gain ~ 13 dB, PAE (maximum) ~ 34% Saturated output power 36 dBm Good IM3 performance: 40dBc at Pin = 15 dBm, and > 35 dBc for Pin < 17.5 dBm V. Paidi, S. Xie UCSB

Summary of IM3 suppression Class B Class A Class C Class AB Psat Low output power levels (Pout 36 dBc, Class A > 45 dBc). Higher output power levels, Class A behaves almost the same as Class B. Class AB and C exhibit more distortion compared to Class A and B. V. Paidi, S. Xie UCSB

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

Comparison between Common Drain and Common source designs V. Paidi, S. Xie UCSB 12 dB Common Drain Common Source Common drain and common source designs are @ 10GHz Both have 36 dBm of saturated output power.1.2 mm GaN HEMTs are used. Common drain design has ~12 dB superior IM3 suppression over the equivalent Common Source design. At 1W total output power Common drain exhibits 46 dBc IMD3 Common source exhibits 36 dBc IMD3.

Common Drain Class B Power Amplifier V. Paidi, S. Xie UCSB Specifications 37 dBm saturated output power at 5 GHz 8 dB Class B gain, 4-6 GHz bandwidth. 38% maximum PAE 44 dBc at 1W total output power under Class B bias. Being fabricated by Shouxuan Xie Layout ~6 mm X 2.5mm P sat ~ 37 dbm PAE ~ 38 % IMD3 > 42 dBc for Pout <2 W

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

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 dB @ 175 GHz single stage amplifier in InP TSHBT technology, Miguel et.al., 12 dB @ 170 GHz three stage CE amplifier in InP TSHBT technology, Miguel et. al., 3-stage amplifier with 12-15 dB gain from 160-190 GHz, InP HEMT, Lai et. al. 6-stage amplifier with 20  6 dB from 150-215 GHz, InP HEMT, Weinreb et. al. Power amplifier results 12.5 dBm @90 GHz with 8.6 dB gain in TS InP DHBT technology, Yun et. al., 14-16 dBm @140-170 GHz with 10 dB gain in InP HEMT technology, Lorene et. al., 14-16 dBm @65-145 GHz with > 10 dB gain in InP HEMT technology, Lorene et. al.,

Why mesa -InP HBTs for 140- 220 GHz power amplifiers ? f max > 400 GHz for 2100A Collector, 300A base HBT ( Technologies like SiGe have f max ~ 210 GHz Jae- Sung Rieh et al., IBM ( IPRM 2003) ) High bandwidth as f t > 250 GHz for 2100A Collector, 300A base HBT Current density > 3 mA/  m 2 at Vbe = 0.7 V and Vcb = 0 V for T c = 2100A. Vbr,ce 0 > 6V Low thermal resistance.

Layer Structure UCSB Mattias, Zach InP Emitter n + doped P + InGaAs Base: doping grading 2100 Å n - InP Collector MaterialDoping (cm -3 )Thickness (  ) n-InGaAs3∙10 19 300 n-InP3∙10 19 1000 n-InP8∙10 17 100 n-InP5∙10 17 500 p+-InGaAs5-8∙10 19 (C)350 n-InGaAs1.5∙10 16 200 Base Collector Grade 1.5∙10 16 240 n-InP3∙10 18 30 n-InP1.5∙10 16 1630 n+-InP1.5∙10 19 100 n+-InGaAs2∙10 19 100 n+-InP2∙10 19 3000 InPSIN/A

Mesa IC Process: Key Features  Slide 1

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

DC and RF measurements 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, A C / A E = 5 f  = 282 GHz, f max = 400 GHz Measurement condition: V CE = 1.7 Volts, J c = 3.6 mA/  m 2 I B = 50  A per step DC beta  = 20 V br = 7 V UCSB Mattias, Zach

Thermal considerations Device geometry: emitter metal = 0.8  12.0  m 2 V br = 7 V, I max = 3 mA/  m 2. θ th = 1.25 K/ mW. ( Dr. Ian Harrison’s simulations) Bias conditions, VCE = 3.5 V, IC = 13 mA (1.5 mA/  m 2 ). The device is thermally stable even without external ballast resistance However, improvements in R ex could be dangerous. Few backup designs with ballast resistance are included.

Single stage Common Base G band ( 140- 220 GHz) power amplifier in InP DHBT technology Objectives: G band, P sat ~ 20 dBm Approach: InP mesa-DHBTs, microwave amplifier design Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0 =180 GHz, BW 3dB ~ 45 GHz, G T =5.3 dB, P sat ~ 20 dBm. common base PA 2 x2x0.8  m x 12  m, A E =38  m 2

Two stage Common Base G band ( 140-220 GHz) power amplifier in InP DHBT technology Objectives: G band, P sat ~ 19.5 dBm Approach: InP mesa-DHBTs, microwave amplifier design Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0 =180 GHz, BW 3dB ~ 45 GHz, G T =8.7 dB, P sat ~ 19.5 dBm. common base PA 6 x 0.8  m x 12  m, A E =58  m 2

Cascode G band ( 140-220 GHz) power amplifier in InP DHBT technology Objectives: G band, P sat ~ 16.5 dBm Approach: InP mesa-DHBTs, microwave amplifier design Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0 =180 GHz, BW 3dB ~ 45 GHz, G T =8.5 dB, P sat ~ 16.5 dBm. Cascode PA 4 x 0.8  m x 12  m, A E =38 mm 2

Two stage Common Base G band ( 140- 220 GHz) power amplifier With Emitter ballasting Resistance Objectives: G band, P sat ~ 16.5 dBm Approach: InP mesa-DHBTs, microwave amplifier design, 1Ώ per each finger, ~ 20 Ώ /  m2 Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0 =180 GHz, BW 3dB ~ 45 GHz, G T =8 dB, P sat ~ 16.5 dBm. common base PA 4 x 0.8  m x 12  m, A E =38  m 2

Single stage Common Base W band ( 75-110 GHz) Power Amplifier Objectives: W band, P sat ~ 20 dBm Approach: InP mesa-DHBTs, microwave amplifier design, Simulations: S-parameter and harmonic and momentum simulation in ADS Accomplishments: f 0 =100 GHz, BW 3dB ~ 45 GHz, G T =8 dB, P sat ~ 20 dBm. common base PA 4 x 0.8  m x 12  m, A E =38  m 2

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

Successful fabrication of X-band Class B Power amplifier in GaN 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 InP mesa DHBT technology. Accomplishments

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

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

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

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

Best IM3 suppression is achieved at Class B and Class A UCSB Simulations of Class B Contd. S. Xie, V. Paidi Class B bias: C/IMD3~44dBc PAE ~ 48% Class A bias C/IMD3~42dBc PAE ~ 35% Class AB bias Class C bias

Measurement setup UCSB Single tone from 4 GHz to 12 GHz; Two-tone measurement at f1 = 8 GHz, f2 = 8.001 GHz; Bias sweep: Class A (Vgs = -3.1V), Class B (Vgs = -5.1V, Class C (Vgs = - 5.5 V) and AB (Vgs = -4.5 V). Measurements: V. Paidi, S. Xie

Class B vs. Class A Class B Class A IM3 suppression and PAE of two-tonePAE of single tone Class B Class A Maintaining good IM3 suppression Class B can get 10% PAE improvement over Class A during low distortion operation. V. Paidi, S. Xie UCSB

Class A bias @Vgs = - 3.1V f 1,f 2 2f 1 -f 2, 2f 2 -f 1 Single tone performance @ f 0 = 8GHz: Two tone performance @ f 1 =8GHz, and f 2 =8.001GHz : Saturated output power 36 dBm Good IM3 performance at low power level but becomes bad rapidly at high power levels Saturated output power each tone ~ 33dBm V. Paidi, S. Xie UCSB PAE (maximum) ~ 34%

UCSB Linearity Analysis-C gs vs V gs V. Paidi, S. Xie Anti-symmetric C gs vs V gs characteristics of GaN HEMTs on SiC C 2 is small due to the anti-symmetric Cgs vs Vgs Even-part creates distortion

UCSB Linearity Analysis-C gs vs V gs Contd. V. Paidi, S. Xie Class B bias has low distortion

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

Summary of All Designs UCSB paidi Design Topologyf 0, GHz Area(  m 2 ) P sat, dBmGainBW 3dB Common Base, Single Stage404 x 0.8 x 1220 dBm10 dB30 GHz Common Base, Single Stage604 x 0.8 x 1220 dBm10 dB35 GHz Common Base, Single Stage804 x 0.8 x 1220 dBm10 dB35 GHz Common Base, Single Stage1004 x 0.8 x 1220 dBm8 dB45 GHz Common Base, Single Stage1204 x 0.8 x 1220 dBm7.5 dB55 GHz Common Base, Single Stage1402 x 0.8 x 1216.5 dBm8.3 dB40 GHz Common Base, Single Stage1602 x 0.8 x 1216.5 dBm7.5 dB40 GHz Common Base, Single Stage1802 x 0.8 x 1216.5 dBm5.6 dB55 GHz Common Base, Single Stage2002 x 0.8 x 1216 dBm5.6 dB45 GHz Common Base, Single Stage2202 x 0.8 x 1216 dBm3.8 dB50 GHz Common Base, Single Stage1402 x 2 x 0.8 x 1220 dBm7.6 dB60 GHz

Summary of All Designs UCSB paidi Design Topologyf 0, GHz Area(  m 2 ) P sat, dBmGainBW 3dB Common Base Single Stage1602 x 2 x 0.8 x 1220 dBm7.1 dB45 GHz Common Base Single Stage1802 x 2 x 0.8 x 1220 dBm5.4 dB55 GHz Common Base Single Stage2002 x 2 x 0.8 x 1219 dBm4.7 dB60 GHz Common Base Single Stage (no cap)1004 x 0.8 x 1220 dBm9 dB30 GHz Common Base Single Stage (no cap)1204 x 0.8 x 1220 dBm7 dB30 GHz Common Base Single Stage (no cap)1402 x 0.8 x 1217 dBm7 dB55 GHz Common Base Single Stage (no cap)1802 x 0.8 x 1217 dBm5.3 dB40 GHz Common Base Single Stage (no cap)2002 x 0.8 x 1216 dBm4 dB70 GHz Common Base Two Stage1404 x 0.8 x 1217 dBm16 dB35 GHz Common Base Two Stage1406 x 0.8 x 1220 dBm15 dB40 GHz Common Base Two Stage1804 x 0.8 x 1217 dBm9.3 dB60 GHz

Summary of All Designs UCSB paidi Design Topologyf 0, GHz Area(  m 2 ) P sat, dBmGainBW 3dB Common Base Two Stage1806 x 0.8 x 1219.5 dBm8.6 dB45 GHz Common Base Two Stage2004 x 0.8 x 1217 dBm10 dB50 GHz Common Base Two Stage ( no cap)1804 x 0.8 x 1217 dBm10.5 dB45 GHz Common Base Two Stage ( no cap) Ballast resistance 20 ohm  m 2 1804 x 0.8 x 1217 dBm8.6 dB50 GHz Common Base Two Stage ( no cap) Ballast resistance 40 ohm  m 2 1804 x 0.8 x 1217 dBm7.2 dB50 GHz Cascode1204 x 0.8 x 1217 dBm13 dB35 GHz Cascode1404 x 0.8 x 1217 dBm8 dB110GHz Cascode1604 x 0.8 x 1217 dBm8 dB40 GHz Cascode1804 x 0.8 x 1217 dBm8.5 dB50 GHz Cascode2004 x 0.8 x 1217 dBm4.5 dB190 GHz

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 GaN HEMT technology is designed and 36dBm of saturated power and 35dBc of IM3 suppression are obtained. Class B is better than Class A because it can get good IM3 performance comparable to that of Class A, while providing more than 10% improvement in PAE under low distortion operation. UCSB Conclusions S. Xie, V. Paidi

Chip photograph of Class B power amplifier (Approximately 6mmX1.5mm) Air bridges Source Drain Gate 1 Gate 2 UCSB V. Paidi, S. Xie

Comparison between Common Drain and Common source designs Contd. V. Paidi, S. Xie UCSB Class ABClass C Class B Class A IM3 suppression at 1W total output power as a function of bias point Common source Common Drain

Common Drain Class B Power Amplifier V. Paidi, S. Xie UCSB Layout ~6 mm X 2.5mm Specifications 37 dBm saturated output power at 5 GHz 8 dB Class B gain, 4-6 GHz bandwidth. 38% maximum PAE 44 dBc at 1W total output power under Class B bias.

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 GaN HEMT at X- band); Class A: Ideal PAE 50%, feasible PAE 20-30%. V in V out = V DS1 – V DS2 0 180 0 +V in -V in V DS 2 V DS 1 UCSB How does push-pull Class B PA work? V. Paidi, S. Xie

Common Base Power Amplifier @40GHz Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 21 dBm Approximate Layout (1.1 mm X0.3 mm)Performance gain > 10 dB

Common Base Power Amplifier @60GHz Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout > 21 dBm Approximate Layout (0.7 mm X0.3 mm)Performance gain > 10 dB

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout > 20 dBm Approximate Layout (0.5 mm X0.3 mm)Performance gain > 8 dB Common Base Power Amplifier @100GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~2 fingersX0.8X12 um2 Pout > 16 dBm Approximate Layout (0.4 mm X0.3 mm)Performance gain ~ 5 dB Common Base Power Amplifier @180GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~2 fingersX0.8X12 um2 Pout ~ 16 dBm Approximate Layout (0.4 mm X0.3 mm)Performance gain ~ 5 dB Common Base Power Amplifier @200GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 20 dBm Approximate Layout (0.7 mm X0.6 mm)Performance gain ~ 7.5 dB Common Base Power Amplifier @140GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 16 dBm Approximate Layout (1 mm X0.7 mm)Performance gain ~ 15dB Two-stage Common Base Power Amplifier @140GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~6 fingersX0.8X12 um2 Pout ~ 20 dBm Approximate Layout (1.3 mm X0.7 mm)Performance gain ~ 15dB Two-stage Common Base Power Amplifier @140GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 16.5 dBm Approximate Layout (1.3 mm X0.7 mm) Performance gain ~ 10dB Two-stage Common Base Power Amplifier @180GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~6 fingersX0.8X12 um2 Pout ~ 20 dBm Approximate Layout (1.3 mm X0.7 mm)Performance gain ~ 8.5dB Two-stage Common Base Power Amplifier @180GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 16.5 dBm Approximate Layout (1.3 mm X0.7 mm)Performance gain ~ 10dB Two-stage Common Base Power Amplifier @200GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout > 17 dBm Approximate Layout (0.5 mm X0.6 mm)Performance gain ~ 8dB Cascode Power Amplifier @140GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 16.5 dBm Approximate Layout (0.5 mm X0.6 mm)Performance gain ~ 8dB Cascode Power Amplifier @180GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout ~ 19 dBm Approximate Layout (0.5 mm X0.3 mm)Performance gain ~ 8dB Common Base Power Amplifier (No Cap design) @100GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~2 fingersX0.8X12 um2 Pout ~ 15.5 dBm Approximate Layout (0.5 mm X0.3 mm)Performance gain ~ 7dB Common Base Power Amplifier (No Cap design) @140GHz

Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~4 fingersX0.8X12 um2 Pout > 16 dBm Approximate Layout (0.3 mm X0.3 mm)Performance gain ~ 10dB Two-stage Common Base Power Amplifier (No Cap design) @180GHz

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

Thermal Structures --- 2 finger device with 0,4,8 ballasting(0.8X12)

GaN HEMT Model

GaN HEMT Model Contd.-Gm block Variables -------- gm, ft, vp, fudfactor(0.05 here) ---- automatic Gds modeling. Probably more accurate.

GaN 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 10V Vds increase. This has been more accurately modeled in this new Device model.

GaN HEMT Model Contd.-Gm block a discussion The Id-Vds characteristics of a 1.2 mm device.

GaN HEMT Model Contd.-Gm block a discussion The Id-Vgs characteristics of a 1.2 mm device at Vds= 15V.

GaN HEMT Model Contd.-Cgs

GaN HEMT Model Contd.-Cgs The Id-Vgs characteristics of a 1.2 mm device at Vds= 15V.

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

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

Dual Gate device and linearity concerns. model:

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

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

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

Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity Biased at Class AB -4.5V here:

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

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

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

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

Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity Biased at Class AB -4.5V:

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

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

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:

Single Gate device and linearity concerns. Common source Circuit Design

Single Gate device and linearity concerns. Common drain Circuit Design

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

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

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

Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Class AB -4.5V:

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

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

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

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

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity Class AB -4.5V:

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

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

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class B -6.5V:

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class C -7.5V:

Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class AB -4.5V:

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

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

Common Drain Circuit on chip right now! Class B -6.5V

Common Drain Circuit on chip right now! Class C -7.5V

Common Drain Circuit on chip right now! Class AB -4.5V

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

Common Drain Circuit on chip right now! Class B -6.5V--- Two tone simulation

Class B two-tone output spectrum Pout = 4 dBm IM3 = 43 dBc Low input power Medium input power 1 Medium input power 2High input power Pout =18 dBm IM3 = 39 dBc Pout = 22 dBm IM3 = 40 dBc Pout = 26 dBm IM3 = 25 dBc

Class A two-tone output spectrum Pout = 10 dBm IM3 > 50 dBc Pout = 27 dBm IM3 = 31 dBc Pout = 31 dBm IM3 = 15 dBc Low input power Medium input power 2High input power Medium input power 2 Pout = 23 dBm IM3 = 42 dBc

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

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

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