Kanin Chu

Multi-Watt Wideband MMICs in GaN and GaAs

A comparison is presented of 4 to 18 GHz MMIC power amplifiers implemented in AlGaN-GaN HEMT and GaAs PHEMT with common circuit design technology. Both GaN and GaAs MMICs were designed as non-uniform distributed power amplifiers and achieved approximately 4 Watts over the band. The circuit complexity of the GaAs circuit is much greater than for GaN, as shown by the relative transistor output peripheries of 14.4 mm and 2 mm. The authors believe that both the GaN and GaAs MMICs have higher power than any published result of comparable bandwidth.

Decade bandwidth 2 to 20 GHz GaN HEMT power amplifier MMICs in DFP and No FP technology

Design and performance of power amplifiers that have established new benchmarks for 2 to 20 GHz power are reported. The Dual Field Plate (DFP) amplifier achieved a P3dB of 26.3 Watts max, 15.4 Watts average, 7.1 Watts min with 38.3 % max, 19.8 % average, 5.9 % min PAE and 11.2 dB max, 8.6 dB average, 5.0 dB min power gain from 2 to 20 GHz. Using an improved device, the No FP amplifier achieved a P3dB of 21.6 Watts max, 16.0 Watts average, 9.9 Watts min with 35.7 % max, 25.9 % average, 15.3 % min PAE and 11.1 dB max, 9.7 dB average, 8.0 dB min power gain from 2 to 20 GHz. This output power, bandwidth, and efficiency is superior to the best previously reported results for both GaN HEMT and PHEMT power amplifiers.

A 50nm MHEMT millimeter-wave MMIC LNA with wideband noise and gain performance

A 50nm MHEMT millimeter-wave MMIC low noise amplifier with state-of-the-art performance is reported. The 3-stage LNA exhibits on-wafer noise figure (NF) as low as 1.6dB with 25dB gain at 80GHz, and also shows unprecedented wideband performance, with 20dB minimum gain across the 30-100GHz band and NF <;2.5dB over the 43-90GHz band. An LNA packaged in a WR-12 module has flange NF of 2.0dB over 74-80GHz and NF <;2.6dB with 27 ± 2dB gain across the full 60-90GHz waveguide band.

Wideband 1 to 6 GHz Ten and Twenty Watt Balanced GaN HEMT Power Amplifier MMICs

Design and performance of power amplifiers that have established benchmarks for 1 to 6 GHz power are reported. The 6 mm periphery balanced amplifier achieved a P3dB of 14.5 Watts max, 11.1 Watts average, 8.2 Watts min with 46.1 % max, 31.8 % average, 18.1 % min PAE and 9.6 dB max, 8.5 dB average, 7.5 dB min power gain from 1 to 6 GHz. The 8 mm periphery balanced amplifier achieved a P5dB of 26.7 Watts max, 20.6 Watts average, 13.9 Watts min with 44.4 % max, 30.8 % average, 17.8 % min PAE and 10.6 dB max, 10 dB average, 8.4 dB min power gain from 1 to 7 GHz. This output power, bandwidth, and efficiency is superior to the best previously reported results for both GaN HEMT and PHEMT power amplifiers [1, 2, 3].

0.1-

We have developed 0.1-μm gate-length InAlN/GaN high electron-mobility transistors (HEMTs) for millimeterwave (MMW) power applications, particularly at 71-76 and 81-86 GHz bands. The impacts of depth and width of the gate recess groove on electrical performance have been analyzed and compared. Competing passivation technologies, atomic layer deposition (ALD) aluminum oxide (Al2O3) and plasma-enhanced chemical vapor deposition (PECVD) SiN, have also been assessed in terms of dc, pulsed-IV, and high-frequency characteristics. It has been found that while PECVD SiN-passivated HEMTs and the monolithic microwave integrated circuits slightly underperform their ALD Al2O3-passivated counterparts, their MMW power performance can be further boosted with the gate recess due to the improved aspect ratio and scaling characteristics. When biased at a drain voltage of 10 V, a first-pass two-stage power amplifier design based on recessed PECVD SiN-passivated 0.1-μm depletion-mode devices has demonstrated an output power of 1.63 W with a 15% power-added efficiency at 86 GHz.

\mu \text{m}

Under the DARPA-sponsored ICECool Applications program, a microchannel cooling system using a 50-50 ethylene glycol-water mixture was optimized for cooling a high-power GaN-on-Diamond Monolithic Microwave Integrated Circuit (MMIC). Automated multi-objective optimization of the microchannel passages yielded an optimized design with a predicted thermal resistance of 22.4 K·cm2/kW at a pressure drop of only 121.4 kPa for an inlet temperature of 40°C. These values were corroborated by a coupled thermofluid analysis that included a detailed treatment of both the gate region and microchannel cooling geometry. Several versions of prototype coolers were fabricated, with one set consisting of pairs of coolers joined at their heated faces. These cooler pairs were used in heat exchange tests to characterize the average thermal resistance and the flow performance of the coolers. The performance testing results were consistent with the analytic predictions. Based on the analytical and experimental results, the system may be operated at inlet temperatures as high as 65°C without exceeding the transistor junction temperatures of 240 °C required for 106 hour mean-time-to -failure. The higher inlet temperature ameliorates system penalties associated with rejection of waste heat to ambient heat sinks.Copyright

InAlN/GaN High Electron-Mobility Transistors for Power Amplifiers Operating at 71–76 and 81–86 GHz: Impact of Passivation and Gate Recess

In this work, we report on an innovative approach which integrates GaN-on-Diamond microstrip MMICs with a state-of-the-art microchannel cooler and provides a significant thermal advantage for high power GaN applications. Specifically, we describe efforts to develop a wide bandwidth, GaN-on-Diamond MMIC power amplifier that achieves greater than 3x RF power density compared to GaN on SiC while operating at a MMIC heat flux of >1kW/cm2 and maintaining junction temperatures below the estimated targets to achieve 106 hrs lifetime by employing a high performance, liquid phase, microchannel cooler capable of a volumetric heat dissipation rate of >10kW/cm3. To date, no prior work has been reported for GaN-on-Diamond microstrip MMICs.