Aaron Oki

A 108-GHz InP-HBT monolithic push-push VCO with low phase noise and wide tuning bandwidth

This paper reports on what is believed to be the highest frequency bipolar voltage-controlled oscillator (VCO) monolithic microwave integrated circuit (MMIC) so far reported. The W-band VCO is based on a push-push oscillator topology, which employs InP HBT technology with peak f/sub T/s and f/sub max/s of 75 and 200 GHz, respectively. The W-band VCO produces a maximum oscillating frequency of 108 GHz and delivers an output power of +0.92 dBm into 50 /spl Omega/. The VCO also obtains a tuning bandwidth of 2.73 GHz or 2.6% using a monolithic varactor. A phase noise of -88 dBc/Hz and -109 dBc/Hz is achieved at 1- and 10-MHz offsets, respectively, and is believed to be the lowest phase noise reported for a monolithic W-band VCO. The push-push VCO design approach demonstrated in this work enables higher VCO frequency operation, lower noise performance, and smaller size, which is attractive for millimeter-wave frequency source applications.

A 2 Watt, Sub-dB Noise Figure GaN MMIC LNA-PA Amplifier with Multi-octave Bandwidth from 0.2-8 GHz

This paper reports on a 0.2-8 GHz high dynamic range GaN MMIC LNA-PA which achieves sub-dB noise figure and a PldB of 2 watts. The GaN MMIC utilizes a 0.2 mum AlGaN/GaN-SiC HEMT technology with an fT ~75 GHz. At high power bias (15 V/400 mA), the MMIC amplifier achieves sub-dB NF ~0.7-0.9 dB over a 2-8 GHz band. At low bias(12 V, 200 mA), the amplifier achieves ~0.5dB over the same band. This is believe to be the lowest NF reported for a multi-octave MMIC amplifier in the S-and C-band frequency range. In addition, the amplifier obtains ultra high linearity with an OIP3 of 43.2-46.5 dBm and P1 dB of 32.8-33.2 dBm (2 watts) over a 2-6 GHz bandwidth. The PAE at P1 dB is ~28.6-31%. The Psat is 34.2 dBm with 39% PAE @ 2 GHz. To our knowledge, this is the first report of a multi-octave MMIC amplifier with sub-dB NF and a pout >2 Watt.

Multi-decade GaN HEMT Cascode-distributed power amplifier with baseband performance

This paper reports on multi-decade bandwidth GaN HEMT Cascode-distributed power amplifier designs which achieve performance from base-band to over 20 GHz. The GaN MMICs are based on a 0.2um AlGaN/GaN low noise T-gate HEMT technology with an fT ∼ 75 GHz. To increase the MMIC power capability of this low noise GaN technology, a cascode DA design approach was employed which can operate at twice the recommended Vds voltage. The resulting amplifiers achieve 1–4 Watts of saturated CW power from 100MHz to over 20GHz at an operating voltage of 30V. Typical OIP3 ≫ 40 dBm and NF of 3 dB were also achieved. Compared to equivalent designs in a similar 0.15um GaAs PHEMT low noise technology fabricated in the same foundry, these multi-decade GaN HEMT MMIC DAs obtain 6 dB higher output power and 5.8–6.6dB higher OIP3 while achieving comparable gain, noise figure, and bandwidth. These are believed to be the first multi-decade GaN power distributed amplifiers that have been demonstrated and can enable future ultra-wideband frequency agile and software defined radio systems that require baseband to microwave frequency operation.

1-Watt Conventional and Cascoded GaN-SiC Darlington MMIC Amplifiers to 18 GHz

A 0.2 mum T-gate GaN-SiC HEMT technology with fT-70 GHz are used to achieve GaN Darlington MMIC Amplifiers with bandwidths up to 18 GHz. Both conventional Darlington and Cascoded-Darlington feedback designs were fabricated and measured. The Darlington Cascode obtains 14.7 dB gain and a bandwidth of 0.05-12.3 GHz. The conventional Darlington obtains 11 dB gain and a record 0.05-18.7 GHz multi-decade bandwidth for a GaN Darlington. These are the highest BWs reported for GaN Darlington MMIC amplifiers. In addition, P1dB ~1 Watt and > 40 dBm OIP3 was obtained beyond 4 GHz. To our knowledge, these results represent the widest bandwidths so far demonstrated for fully monolithic GaN Darlington MMICs.

Digital signal processing - up to microwave frequencies

Digital logic integrated circuits are advancing toward ever higher speeds of operation. Clock frequencies already exceed 1 GHz in some Si CMOS-based consumer products, and even higher speeds are attainable in specialized technologies, such as those based on GaAs, InP, and SiGe bipolar and field-effect transistors. Digital approaches may be used to carry out a variety of functions important in microwave systems, including signal generation, filtering, and frequency conversion. The digital implementation provides a variety of potential benefits, including lack of sensitivity to aging and component inaccuracies, flexibility, and programmability. The dynamic range and degree of nonlinearity can be specified by design. Signal storage and memory functions are easily accomplished. Single-chip integration of digital and microwave systems are also facilitated. The application of digital techniques in domains previously considered to be analog is an important ongoing technology thrust, which may be expected to accelerate. This paper reviews the prospects of digital techniques for microwave systems, and briefly describes the state-of-technology and future possibilities.

A 44-GHz-high IP3 InP HBT MMIC amplifier for low DC power millimeter-wave receiver applications

This paper reports on what is believed to be the highest IP3/P/sub dc/ power linearity figure of merit achieved from a monolithic microwave integrated circuit (MMIC) amplifier at millimeter-wave frequencies. The 44 GHz amplifier is based on an InP heterojunction bipolar transistor (HBT) technology with f/sub T/s and f/sub max/s of 70 and 200 GHz, respectively. The 44-GHz amplifier design consists of four prematched 1/spl times/l0/spl mu/m/sup 2/ four-finger (40-/spl mu/m/sup 2/) heterojunction bipolar transistor (HBT) cells combined in parallel using a compact /spl lambda//8 four-way microstrip combiner. Over a 44-50-GHz frequency band, the amplifier obtains a gain of 5.5-6 dB and a peak gain of 6.8-7.6 dB under optimum gain bias. At a low bias current of 48 mA and a total dc power of 120 mW, the amplifier obtains a peak IP3 of 34 dBm, which corresponds to an IP3/P/sub dc/ power ratio of 21:1, a factor of two better than previous state-of-the-art MMICs reported in this frequency range. By employing a thin, lightly doped HBT collector epitaxy design tailored for lower voltage and higher IP3, a record IP3/P/sub dc/, power ratio of 42.4:1 was also obtained and is believed to be the highest reported for an MMIC amplifier of any technology. The new high-linearity HBTs have strong implications for millimeter-wave receiver as well as low-voltage wireless applications.

Monolithic 77- and 94-GHz InP-based HBT MMIC VCOs

This paper presents the development of 77- and 94-GHz monolithic fundamental mode VCOs using InP-based HBT MMIC technology. The InP-based HBT performance was improved by base mesa undercutting the base ohmic along two sides to reduce the base-collector junction capacitor by 40% which results in f/sub T/ and f/sub max/ of 70 and 170 GHz, respectively. By using this improved HBT device, the 77-GHz VCO exhibits a measured oscillation frequency of 77.6 GHz with a peak output power of -3 dBm, while the 94-GHz VCO demonstrates a measured oscillation frequency of 94.7 GHz with a peak output power of -3.5 dBm. The 94-GHz VCO is the highest frequency fundamental mode oscillator ever reported using bipolar device technology.

Advanced Heterogeneous Integration of InP HBT and CMOS Si Technologies

Northrop Grumman Aerospace Systems (NGAS) is developing an Advanced Heterogeneous Integration (AHI) process to integrate III-V semiconductor chiplets on CMOS wafers under the Compound Semiconductor Materials on Silicon (COSMOS) DARPA program. The objective of the program is to have a heterogeneous interconnect pitch and length less than 5 um to enable intimate transistor scale integration. This integration will enable significant improvement in dynamic range and bandwidth of high performance mixed signal circuits.

A Cool, Sub-0.2 dB Noise Figure GaN HEMT Power Amplifier With 2-Watt Output Power

This paper reports on a S-, C-band low-noise power amplifier (LNPA) which achieves a sub-0.2 dB noise figure (NF) over a multi-octave band and a saturated output power (Psat) of 2 W at a cool temperature of -30degC . The GaN MMIC is based on a 0.2 mum AlGaN/GaN-SiC HEMT technology with an fT ~ 75 GHz. At a cool temperature of -30degC and a power bias of 15 V-400 mA, the MMIC achieves 0.25-0.45 dB average NF over a 2-8 GHz band and a linear P1dB of 32.8 dBm ( ~ 2 W) with 25% power-added efficiency (PAE). At a medium bias of 12 V-200 mA, the amplifier achieves 0.1-0.2 dB average NF across the same band and a P1dB of 32.2 dBm (1.66 W) with 35% PAE. The corresponding saturated output power is greater than 2 W. At a low noise bias of 5 V-200 mA, a remarkable 0.05-0.15 dB average NF is achieved with a P1dB > 24 dBm and PAE ~ 33%. These results are believed to be the lowest NF ever reported for a multi-octave fully matched MMIC amplifier capable of > 2 W of output power.

The effect of RF-driven gate current on DC/RF performance in GaAs pHEMT MMIC power amplifiers

This paper describes RF-driven gate current effects on the dc/RF performance of 0.15-/spl mu/m (gate length) 2-mil (substrate thickness) GaAs pseudomorphic high-electron mobility transistor (pHEMT) monolithic microwave integrated circuit power amplifiers (PAs). High gate current is generated in PAs under RF drive at room temperature. A long-term lifetest of PAs with various gate currents induced by RF drive was performed to investigate the effect of RF-driven gate current on dc/RF performance in GaAs pHEMT PAs. Accordingly, an empirical model was developed to predict the dc/RF performance of V-band PA modules by the end of life (EOL). This information is crucial for system engineers in order to budget sufficient output power so that the system can still maintain performance capability by EOL.