Defining Application Spaces for High Power GaN David Runton, Dave Aichele, Michael LeFevre, Christopher Burns RFMD, Chandler, AZ Summary • Exploring the options for GaN • Value Proposition • Market Segments • Product alignment • Timing is NOW! Data is REAL! • Enabling Wide Bandwidth • Enabling Very High Power • Enabling Future Infrastructure • Enabling High Efficiency • Conclusions GaN Value Proposition End User Benefits GaN-on-SiC S G D GaN SiC High Breakdown Voltage High Power Density Energy Efficient CAPEX Reduce cost: (i) air conditioning (ii) site acquisition (iii) battery OPEX Reduce cost: (i) maintenance (ii) electricity (iii) battery Incr. reliability OEM Benefits Reliable & Compact HPAs Reduced Capacitance High Efficiency Circuit Techniques Lower Heat Dissipation Increase Efficiency High Impedance Multi-band Operation Configurable Radio Increase Bandwidth Reduced: (1) size/complexity (2) cooling (3) weight and (4) cost GaN: Multiple Efficiency Benefits Linearity & Bandwidth Green Improved performance More power efficient Especially for LTE/WiMAX Per mW of RF power Scale Build GaN in existing GaAs fabs Marginal cost delta ε Power & Size More RF power per mm2 Opex/Capex BOM & Running costs reduced Reduced total cost of ownership 48V, 120W GaN 3.5mm2 Equivalent LDMOS Die is ~5X the size GaN vs. LDMOS 440MHz 180W PA Module 90w GaN die 90w LDMOS die 2 per module Efficiency Gain Operating Voltage 84% 26dB 48V 2 per module Efficiency Gain Operating Voltage 74% 22dB 28V Product Alignment Military Communications & Radar Market Military Market Drivers • Radar – provide larger detection area – improve early detection – reduce size & weight • Military Communications S-Band Phase Array Radar JTRS Handheld Radio – improve battery life – multi-standards for inter-operability – wide-band architecture for portable and mobile platforms – Volume COTS model Why GaN • Higher Efficiency – reduce heat sink requirements, smaller size – increase battery life • Wide bandwidth – replace (3 to 5) amplifiers with (1) amplifier – improve engineering efficiency • Higher Power Density & Operating Voltage – increase power with same form factor Product Alignment Cellular Infrastructure Market BTS Market Drivers • Remote Radio Heads – eliminate 3dB cable loss – reduce size & cooling demands • Improve BTS efficiency Cellular Base Station (BTS) RF Power Amplifier Why GaN • Higher Efficiency with latest PA Architectures – reduce heat sink requirements, smaller size – reduce operation expenses / electricity costs • Wide bandwidth & linearity – reduce amplifier inventory – improve engineering efficiency – reduce CapEx & OpEx costs – utilize renewable energy sources • Wideband Platforms – reduce inventory – configurable systems support multi-standards Product Alignment RFMD Product Categories Matched Power Transistors (MPT) High power amplifier; 48V-65V, 200-500W Pulsed; optimized for high power/efficiency, Input/Output matched 25 to 50Ω interface Value RFG1M Series BTS Discrete Devices High power amplifier; 48V 30 to 360W CW; optimized for linear applications, Input matched no output match Wide-Band Power IC (PIC) High power ‘gain block’; 28V to 48V, 10 to 30W CW; optimized wide bandwidth constant gain, 50Ω input matched Unmatched Power Transistor (UPT) High power amplifier; 10-120 watts CW; No input or output match, tunable bandwidth and high peak power/efficiency RFMD GaN-RF Product Details POWER TRANSISTOR SPECIFICATIONS • Voltage: up to 48V • Operating Frequency: DC-7GHz • Output Power: 10 – 120W • Power Gain: 14dB • Drain Efficiency: >50% ATTRIBUTES • Wide Bandwidth • Tunable Bandwidth WIDEBAND POWER-IC SPECIFICATIONS • Voltage: 28V • Operating Frequency: PMR, WCDMA, WiMAX • Output power: < 12 W • Power Gain: 11-14dB • Drain Efficiency: 50% to 75% ATTRIBUTES • Wide bandwidth • 50Ω input impedance GaN die GaAs die INTERNALLY MATCHED FET SPECIFICATIONS • Voltage: up to 65V • Operating Frequency: from 800 – 3.5GHz • Output Power: 30 – 500W • Power Gain = 16dB • Drain Efficiency: >65% ATTRIBUTES • Optimized for High efficiency • Higher impedances GaN die GaN die GaAs die Impedance matching GaN Unmatched Power Transistors • Applications: – – – – – • General purpose broadband amplifiers Civilian/Military radars EW Jammers MILCOM/Public mobile radio Wireless Infrastructure Features/Benefits: – – – – – High Power Density > 5W/mm 48V bias operation 30-120W products available High terminal impedance – tunable wide BW Peak Drain Efficiency ~65% @ 2.1GHz GaN Performance Characterization 2.1GHz 3 temperature characterization Gain variation over temp: 0.011dB/C Three different lots GaN Enables Wider Bandwidth CHALLENGE: Multiple amplifiers needed to cover cellular/WiMAX bands SOLUTION: GaN enables multiple bands covered with a single amplifier 60W GaN WCDMA 8W GaN WiMAX WiMAX 2.5GHz Band WiMAX 3.5GHz Band 10 S11 (dB) S21 (dB) S22 (dB) S12 (dB) 0 LDMOS 5 LDMOS Gain (dB) Return Loss (dB) Gain (dB) Return Loss (dB) 15 -5 -10 -15 -20 -25 -30 2.0 frequency (GHz) 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 frequency (GHz) LDMOS LDMOS 3.8 4.0 GaN Broadband Power IC 30 Applications: – General purpose amplifiers – Public Mobile Radios – Military Communications – EW Jammers 25 Power (W) • Product C 20 15 Product A 10 Product B 5 0 0 • Features: – 28V and 48V, multiple power levels – Small Form Factor, 5mmx6mm Package – Broadband power/gain performance – 50ohm Input impedance match – 1dB gain flatness across bandwidth 0.5 1.0 1.5 2.0 Frequency (GHz) 13 2.5 GaN Broadband Power IC 28V 50MHz to 1.0GHz 15W Amplifier Output power and PAE over frequency Output Power, PAE and Gain at 500 MHz 70 40 42 60 41 50 P3dB 40 40 PAE 39 30 0.0 0.2 0.4 0.6 Frequency (GHz) 0.8 1.0 70 Output Power PAE Gain 35 60 50 30 40 25 30 20 20 15 10 10 0 5 10 15 20 Pin (dBm ) 25 30 35 PAE (%), Gain (dB) 43 Output Power (dBm) 45 PAE (%) 80 P3dB (dBm) 44 GaN Broadband Power IC 28V 30MHz to 2.2GHz 10W Amplifier Output Power, PAE and Gain at 2200 MHz 40 41 60 35 40 50 39 40 Psat 38 30 PAE 37 0.0 0.5 1.0 20 1.5 Frequency (GHz) 2.0 2.5 50 Output Power PAE Gain 40 30 30 25 20 20 10 15 0 5 10 15 20 Pin (dBm ) 25 30 35 PAE (%), Gain (dB) 70 Output Power (dBm) 42 PAE (%) Psat (dBm) Output power and PAE over frequency GaN Enables Very High Power • Applications: – General purpose amplifiers – Air Traffic Control – Military Radar – S-Band Radar • Features: – 48V, 300W Pulse (100us PW,10% DC) – Small form factor 24mmx17.4mm – Broadband power/gain performance – 35ohm I/O impedance match 16 GaN Matched High Power Transistor 48V 2.5GHz to 3.5GHz 300W 17 GaN Enables Infrastructure • • Applications: – Wireless Infrastructure Amplifiers Features: – 48V operation – Input Matched for broadband operation – Easily linearizable using standard DPD algorithms. GaN Enables Software Defined Radio Single tuning performance 2.25-2.7GHz Pout = 45.25dBm, Gain > 13.25dB, Drain Efficiency > 25.5% 3GPP TM1 – 7.5dB PAR @ 0.01% CCDF GaN Enables Higher Efficiency System Complexity GaN dominates - superior material & device properties switch mode EER wideband DPD ET DM LEGEND: DPD Doherty Deployed feed forward unlinearized In development ET-envelope tracking DM-drain modulation DPD-digital pre-distortion EER-envelope elimination & recovery LDMOS offers mature technology, adequate linearity time Increasingly important for linear modulation schemes LTE, WiMAX and future standards GaN Enables High Efficiency - Doherty • Performance • 865-890MHz optimized • 855-910MHz 0.25dB gain flatness • Pout = 50 dBm • Efficiency > 49% • Gain > 17.7dB • ACP (DPD) < -52dBc • Circuit Area Size • 114 x 80 mm • PCB assembled on standard 127 x 127mm reference circuit 20 0 18 -3 Gain (dB) 14 PAR (dB) 12 IRL (dB) -6 -9 -12 10 -15 8 -18 6 -21 4 -24 52 -15 50 -20 48 -25 46 -30 44 -35 42 -40 40 -45 38 -50 36 800 820 840 860 880 900 Frequency (MHz) 920 940 -55 960 IRL (dB) 16 ACP @ 5 MHz (dBc), ALT @ 10 MHz (dBc) Drain Efficiency (%) Gain (dB), PAR (dB) Broadband Doherty Performance WCDMA (3GPP 7.5 dB PAR @0.01% CCDF) Avg Pout = 50 dBm Vdd = 48V Main Idq = 650 mA Peaking Vg = -6.5V NO DPD correction Eff (%) ACP +/- 5 MHz (dBc) ALT +/- 10 MHz (dBc) D rain Efficien cy (% ) Broadband Doherty Performance CW Power Sweep at 882.5MHz 70 65 60 55 50 45 40 35 30 25 20 2x Class AB Vgpk = -8.0V Vgpk = -7.5V Vgpk = -7.0V Vgpk = -6.5V Vgpk = -6.0V Vgpk = -5.5V Vgpk = -5.0V 42 43 44 45 46 47 48 49 50 Pout (dBm) Vdd= 48V, Main Idq = 650 mA 51 52 53 54 55 56 57 GaN Enables High Efficiency Drain Modulation • Use static characterization overlaying statistics of the drive signal • Find “average” operating condition to determine optimum tuning point • Mapped Data to 1 Car, WCDMA TM1, 7.5 dB PAR • 15V – 55 V, 15 dBm – 39 dBm Mapped Performance (PAE, Pout) 7 6 45 46.5 46 Imag Impedances () Max PAE @ 4.00 + j*4.60 Ohms Avg PAE = 68.19% Avg Pwr = 47.30 dBm 45 45.5 42 43 44 5 68 47 47.5 4 66 3 62 Original Impedance Z = 8.0 + j3.6 64 54 56 58 2 58 Meas Imp Mapped PAE Mapped Pout Fixture Opt Tune 60 58 1 0 2 3 4 5 6 7 8 Optimized Impedance Z = 4.00 + j4.60 9 Real Impedances () *See Asbeck P.et al., “Augmented Behavioral Characterization for Modeling the Nonlinear Response of Power Amplifiers”,IEEE MTT-S Digest 2002 GaN PAE Performance vs. Vdd PAE vs VDD 75 Using different criteria to optimize PAE can improve performance 70 65 PAE (%) 60 P2dB follows closely to optimal PAE mapping 55 50 45 Data taken on loadpull fixture with no harmonic tuning Opt PAE P1dB P2dB 40 35 30 15 20 25 30 35 Vdd (V) 40 45 50 55 PAE (%) Gain (dB) GaN Drain Modulation Performance (ABC Model*) Pout (dBm) Pout (dBm) Assumes Linear relationship between Vdd and Pin Peak PAE Point: Z = 4.00 + j*4.60 Ohms Avg PAE = 68.19%, Avg Pout = 47.30 dBm, Avg Gain = 18.69 dB Did not exceed 4.5 dB compression *See Asbeck P.et al., “Augmented Behavioral Characterization for Modeling the Nonlinear Response of Power Amplifiers”,IEEE MTT-S Digest 2002 GaN Advantages in RF Power Enabling the Application Space Wide Bandwidth High Impedance GaN-on-SiC S G GaN SiC Multi-band Operation Configurable Radios High Efficiency D Low Capacitance Enables High Efficiency Circuit Techniques OEM Amplifier Benefits Smaller Heatsink High Power High Breakdown Voltage High Power Density High Thermal Conductivity Compact HPAs Reduced: (1) size/complexity (2) cooling (3) weight and (4) cost