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

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

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

Slide 4 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 %. 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.

Slide 5 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

Slide 6 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

Slide 7 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

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

Slide 9 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

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

Slide 11 Class B = - 5.1V Single tone f 0 = 8GHz: Two tone 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

Slide 12 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

Slide 13 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.

Slide 14 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 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.

Slide 15 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

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

Slide 17 Motivation for GHz power amplifiers and Previous results Applications for electronics in GHz frequency band Wideband communication systems Atmospheric sensing Automotive radar Small signal amplifier results GHz single stage amplifier in InP TSHBT technology, Miguel et.al., GHz three stage CE amplifier in InP TSHBT technology, Miguel et. al., 3-stage amplifier with dB gain from GHz, InP HEMT, Lai et. al. 6-stage amplifier with 20  6 dB from GHz, InP HEMT, Weinreb et. al. Power amplifier results 12.5 GHz with 8.6 dB gain in TS InP DHBT technology, Yun et. al., GHz with 10 dB gain in InP HEMT technology, Lorene et. al., GHz with > 10 dB gain in InP HEMT technology, Lorene et. al.,

Slide 18 Why mesa -InP HBTs for 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.

Slide 19 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∙ n-InP3∙ n-InP8∙ n-InP5∙ p+-InGaAs5-8∙10 19 (C)350 n-InGaAs1.5∙ Base Collector Grade 1.5∙ n-InP3∙ n-InP1.5∙ n+-InP1.5∙ n+-InGaAs2∙ n+-InP2∙ InPSIN/A

Slide 20 Mesa IC Process: Key Features  Slide 1

Slide 21 Mesa IC Process: Key Features  Slide 2

Slide 22 Mesa IC Process: Key Features  Slide 3

Slide 23 Mesa IC Process: Key Features  Slide 4

Slide 24 Mesa IC Process: Key Features  Slide 5

Slide 25 Mesa IC Process: Key Features  Slide 6

Slide 26 Mesa IC Process: Key Features  Slide 7

Slide 27 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 <  ∙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

Slide 28 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

Slide 29 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.

Slide 30 Single stage Common Base G band ( 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

Slide 31 Two stage Common Base G band ( 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

Slide 32 Cascode G band ( 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

Slide 33 Two stage Common Base G band ( 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

Slide 34 Single stage Common Base W band ( 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

Slide 35 Summary of All Designs The mask has GHz : One Single Stage 100 mW design 50 – 70 GHz : One Single Stage 100 mW design 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

Slide 36 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 ( GHz) power amplifiers in InP mesa DHBT technology. Accomplishments

Slide 37 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

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

Slide 39

Slide 40

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

Slide 42 Simulation of class B 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

Slide 43 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

Slide 44 Measurement setup UCSB Single tone from 4 GHz to 12 GHz; Two-tone measurement at f1 = 8 GHz, f2 = GHz; Bias sweep: Class A (Vgs = -3.1V), Class B (Vgs = -5.1V, Class C (Vgs = V) and AB (Vgs = -4.5 V). Measurements: V. Paidi, S. Xie

Slide 45 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

Slide 46 Class A = - 3.1V f 1,f 2 2f 1 -f 2, 2f 2 -f 1 Single tone f 0 = 8GHz: Two tone 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%

Slide 47 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

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

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

Slide 50 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 dBm8.3 dB40 GHz Common Base, Single Stage1602 x 0.8 x dBm7.5 dB40 GHz Common Base, Single Stage1802 x 0.8 x 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

Slide 51 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

Slide 52 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 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 x 0.8 x 1217 dBm8.6 dB50 GHz Common Base Two Stage ( no cap) Ballast resistance 40 ohm  m 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

Slide 53 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

Slide 54 Chip photograph of Class B power amplifier (Approximately 6mmX1.5mm) Air bridges Source Drain Gate 1 Gate 2 UCSB V. Paidi, S. Xie

Slide 55 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

Slide 56 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.

Slide 57 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 DS V in -V in V DS 2 V DS 1 UCSB How does push-pull Class B PA work? V. Paidi, S. Xie

Slide 58 Common Base Power 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

Slide 59 Common Base Power 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

Slide 60 Common Base Power 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 (0.6 mm X0.3 mm)Performance gain > 10 dB

Slide 61 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

Slide 62 Common Base Power 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 > 7 dB

Slide 63 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 (0.5 mm X0.3 mm)Performance gain > 8 dB Common Base Power

Slide 64 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 > 8 dB Common Base Power

Slide 65 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

Slide 66 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

Slide 67 Technology: InP mesa HBT Ft~200 GHz, fmax ~400 GHz Vbr ~ 7V Current density ~ 3mA/um2 Area ~2 fingersX0.8X12 um2 Pout ~ 15 dBm Approximate Layout (0.3 mm X0.3 mm)Performance gain ~ 5 dB Common Base Power

Slide 68 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

Slide 69 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 (0.6 mm X0.5 mm)Performance gain ~ 6.8 dB Common Base Power

Slide 70 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 X0.5 mm)Performance gain ~ 5 dB Common Base Power

Slide 71 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 X0.5 mm)Performance gain ~ 4.5 dB Common Base Power

Slide 72 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

Slide 73 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

Slide 74 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

Slide 75 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

Slide 76 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

Slide 77 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

Slide 78 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

Slide 79 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

Slide 80 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

Slide 81 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 (0.3 mm X0.3 mm)Performance gain ~ 5dB Common Base Power Amplifier (No Cap

Slide 82 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 (0.3 mm X0.3 mm)Performance gain ~ 4dB Common Base Power Amplifier (No Cap

Slide 83 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

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

Slide 85 Thermal Structures finger device with 0,4,8 ballasting(0.8X12)

Slide 86 GaN HEMT Model

Slide 87 GaN HEMT Model Contd.-Gm block Variables gm, ft, vp, fudfactor(0.05 here) ---- automatic Gds modeling. Probably more accurate.

Slide 88 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 V per every 10V Vds increase. This has been more accurately modeled in this new Device model.

Slide 89 GaN HEMT Model Contd.-Gm block a discussion The Id-Vds characteristics of a 1.2 mm device.

Slide 90 GaN HEMT Model Contd.-Gm block a discussion The Id-Vgs characteristics of a 1.2 mm device at Vds= 15V.

Slide 91 GaN HEMT Model Contd.-Cgs

Slide 92 GaN HEMT Model Contd.-Cgs The Id-Vgs characteristics of a 1.2 mm device at Vds= 15V.

Slide 93 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.

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

Slide 95 Dual Gate device and linearity concerns. model:

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

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

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

Slide 99 Dual Gate device and linearity concerns. One step at a time ---- Only Gm non-linearity Biased at Class AB -4.5V here:

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

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

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

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

Slide 104 Dual Gate device and linearity concerns. One step at a time ---- Gm+Cgs non-linearity Biased at Class AB -4.5V:

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

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

Slide 107 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 108 Single Gate device and linearity concerns. Common source Circuit Design

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

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

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

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

Slide 113 Single Gate device and linearity concerns. One Step at a time --- Only Gm nonlinearity Class AB -4.5V:

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

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

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

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

Slide 118 Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs nonlinearity Class AB -4.5V:

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

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

Slide 121 Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class B -6.5V:

Slide 122 Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class C -7.5V:

Slide 123 Single Gate device and linearity concerns. One Step at a time --- Gm+Cgs+Vpshift nonlinearity Class AB -4.5V:

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

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

Slide 126 Common Drain Circuit on chip right now! Class B -6.5V

Slide 127 Common Drain Circuit on chip right now! Class C -7.5V

Slide 128 Common Drain Circuit on chip right now! Class AB -4.5V

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

Slide 130 Common Drain Circuit on chip right now! Class B -6.5V--- Two tone simulation

Slide 131 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

Slide 132 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