James J. Komiak

Fully monolithic 4 watt high efficiency Ka-band power amplifier

Design and performance of a power amplifier that has established a new benchmark for Ka-band power is reported. The amplifier achieved >4 Watts at 25 to 31% PAE with 14 dB of power gain from 29 to 31 GHz. This output power, bandwidth, and efficiency is superior to the best previously reported results. The amplifier is implemented in an improved fully selective 0.15 um power PHEMT process.

Compact, high average power, fiber-pumped terahertz source for active real-time imaging of concealed objects

We have modeled and demonstrated a scalable, compact, fiber-pumped terahertz source based on difference frequency mixing (DFM) in zinc germanium phosphide (ZGP) capable of producing high average and peak-power pulses. Currently, our terahertz source produces 2 mW of average THz power and >40 W of peak power with sub-nanosecond pulses at a repetition rate of 100 kHz in the range of 2-3 THz without cryogenic cooling or ultra-fast optics. This high average power laser-based terahertz output enables the real-time imaging of concealed objects using an off-the-shelf uncooled microbolometer focal-plane array. With this THz system, we have imaged objects obscured inside in a common shipping envelope, demonstrating the potential of compact laser-based terahertz sources for use in security screening applications.

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.

GaN HEMT: Dominant Force in High-Frequency Solid-State Power Amplifiers

The gallium nitride (GaN) high-electron-mobility transistor (HEMT) has emerged as the dominant force in high-frequency solid-state power amplifiers (PAs)-not that it does not have competition. Silicon (Si) bipolar junction transistors (BJTs) and Si laterally diffused metal-oxide-semiconductor (LDMOS) field-effect transistors (FETs) are still commercially available. They are viable alternatives to GaN HEMTs in aerospace/defense applications such as L-band transponders/interrogators for the identification friend or foe; Link 16 data links; electronic warfare; and surveillance radar; and, in the case of Si LDMOSs, commercial cellular base stations. These older technologies can be favored due to their mature heritage, good performance, and low cost. The pseudomorphic HEMT (PHEMT) is ubiquitous in microwave and millimeter-wave power applications. Vacuum electron devices (VEDs) still reign in the regime of brute power. The GaN HEMT has been displacing these technologies as it has matured and costs have come down.

High efficiency wideband 6 to 18 GHz PHEMT power amplifier MMIC

Design and performance of a power amplifier that has established new benchmarks for 6 to 18 GHz power is reported. The amplifier achieved 7.5 Watts max, 5.4 Watts average, 4 Watts min with 36 % max, 22 % average PAE and 12 dB of power gain from 6 to 18 GHz. This output power, bandwidth, and efficiency is superior to the best previously reported results. The amplifier is implemented in a fully selective 0.15 um double recess power PHEMT process.

0.1-

High-performance 0.1-μm InAlN/GaN high electron-mobility transistors (HEMTs) have been successfully developed for power amplifiers operating at E-band (targeting 71-76 and 81-86-GHz bands). High maximum drain current of 1.75 A/mm and maximum extrinsic transconductance of 0.8 S/mm have been achieved for depletion-mode devices. Enhancement-mode HEMTs have also shown maximum drain current of 1.5 A/mm and maximum extrinsic transconductance of 1 S/mm. The selection of atomic layer deposition aluminum oxide (Al2O3) for device passivation enables a two-terminal breakdown voltage of ~25 V, excellent subthreshold characteristics as well as the pulsed-IV featuring little current collapse for both types of HEMTs. When biased at a drain voltage of 10 V, a first-pass two-stage power amplifier design based on 0.1-μm depletion-mode devices has demonstrated an output power of 1.43 W with 12.7% power-added efficiency at 86 GHz, a level of performance that has been attained previously only by state-of-the-art counterparts based on AlGaN/GaN HEMTs at a much higher drain bias and compression level.

\mu \text{m}

We have demonstrated a novel terahertz source based on dual-wavelength amplification in polarization maintaining Yb- doped fiber and frequency mixing in a zinc germanium phosphide (ZGP) crystal. The system consists of two orthogonally polarized signals, whose difference frequency is in the terahertz region, amplified in a single all-fiber amplifier chain and mixed in a ZGP crystal to generate high-peak-power terahertz radiation. Currently, 2 mW of average terahertz power (20 W peak, 20 nJ/pulse) has been produced at a repetition rate of 100 kHz and pulsewidths of 1 ns with a conversion efficiency of 0.137%. We have also developed a terahertz mixing model, which coincides well with our experimental data.

Atomic Layer Deposition Al 2 O 3 Passivated InAlN/GaN High Electron-Mobility Transistors for E-Band Power Amplifiers

The design and performance of a 0.15 um gate length fully selective recess PHEMT power amplifier that has established a new benchmark for Ka-band power is reported. The amplifiers average >3 watts at 30% PAE with 13 dB of power gain at 30 GHz, with a 1 dB gain compression output power of >2.5 watts. The P1dB output power is 2.5 times the best previously reported result for Ka-band MMIC power amplifiers. A 0.5 watt at P1dB driver amplifier is also described.

Compact Fiber-Pumped Terahertz Source Based on Difference Frequency Mixing in ZGP

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].

3 watt Ka-band MMIC HPA and driver amplifier implemented in a fully selective 0.15 /spl mu/m power PHEMT process

We report the design, fabrication and characterization of ultrahigh gain metamorphic high electron-mobility transistors. In this letter, a high-yield 50-nm T-gate process was successfully developed and applied to epitaxial layers containing high indium mole fraction InGaAs channels grown on GaAs substrates. A unique gate recess process was adopted to significantly increase device gain by effectively suppressing output conductance and feedback capacitance. Coupled with extremely small 10 mum times 25 mum via holes on substrates thinned to 1 mil, we achieved a 13.5 dB maximum stable gain (MSG) at 110 GHz for a 30-mum gate-width device. To our knowledge, this is the highest gain performance reported for microwave high electron-mobility transistor devices of similar gate periphery at this frequency, and equivalent circuit modeling indicates that this device will operate at frequencies beyond 300 GHz.