Vamsi Paidi

G-band (140-220 GHz) and W-band (75-110 GHz) InP DHBT medium power amplifiers

We report common-base medium power amplifiers designed for G-band (140-220 GHz) and W-band (75-110 GHz) in InP mesa double HBT technology. The common-base topology is preferred over common-emitter and common-collector topologies due to its superior high-frequency maximum stable gain (MSG). Base feed inductance and collector emitter overlap capacitance, however, reduce the common-base MSG. A single-sided collector contact reduces Cce and, hence, improves the MSG. A single-stage common-base tuned amplifier exhibited 7-dB small-signal gain at 176 GHz. This amplifier demonstrated 8.7-dBm output power with 5-dB associated power gain at 172 GHz. A two-stage common-base amplifier exhibited 8.1-dBm output power with 6.3-dB associated power gain at 176 GHz and demonstrated 9.1-dBm saturated output power. Another two-stage common-base amplifier exhibited 11.6-dBm output power with an associated power gain of 4.5 dB at 148 GHz. In the W-band, different designs of single-stage common-base power amplifiers demonstrated saturated output power of 15.1 dBm at 84 GHz and 13.7 dBm at 93 GHz

High linearity and high efficiency of class-B power amplifiers in GaN HEMT technology

A 36-dBm high-linearity single-ended common-source class-B monolithic-microwave integrated-circuit power amplifier is reported in GaN high electron-mobility transistor technology. We also describe the design and simulation of highly linear and highly efficient common-source and common-drain class-B power amplifiers. Single-ended class-B amplifiers with bandpass filtering have equivalent efficiency and linearity to push-pull configurations. The common-source class-B circuit demonstrates high linearity, greater than 35 dBc of third-order intermodulation (IM3) suppression and high power-added efficiency (PAE) of 34%. Simulations of common-drain class-B designs predict a PAE of 54% with a superior IM3 suppression of more than 45 dBc over a wider range of bias due to the strong series-series negative feedback offered by the load resistance.

Transistor and circuit design for 100-200 GHz ICs

Compared to SiGe, InP HBTs offer superior electron transport properties but inferior scaling and parasitic reduction. Figures of merit for mixed-signal ICs are developed and HBT scaling laws introduced. Device and circuit results are summarized, including a simultaneous 450 GHz f/sub /spl tau// and 490 GHz f/sub max/ DHBT, 172-GHz amplifiers with 8.3-dBm output power and 4.5-dB associated power gain, and 150-GHz static frequency dividers (a digital circuit figure-of-merit for a device technology). To compete with advanced 100-nm SiGe processes, InP HBTs must be similarly scaled and high process yields are imperative. Described are several process modules in development: these include an emitter-base dielectric sidewall spacer for increased yield, a collector pedestal implant for reduced extrinsic C/sub cb/, and emitter junction regrowth for reduced base and emitter resistances.

75 GHz 80 mW InP DHBT power amplifier

We report a 75 GHz MMIC power amplifier in InP/InGaAs/InP DHBT transferred-substrate technology. The amplifier has 256 /spl mu/m/sup 2/ total emitter area and exhibits a power gain of 5.5 dB at 75 GHz and a saturated output power of 19 dBm (80mW) under 1-dB gain compression. The DHBT employed by the amplifier has a lightly doped InP emitter epitaxial layer between the emitter and the emitter cap layer as a distributed ballast resistance to improve thermal stability. To our knowledge, this is the highest reported output power for a W-band HBT power amplifier.

High-linearity class B power amplifiers in GaN HEMT technology

A 36-dBm, high-linearity, single-ended class B MMIC power amplifier is reported in GaN HEMT technology. The circuit demonstrates high linearity, greater than 35 dBc of third-order intermodulation (IM3) suppression and high power added efficiency (PAE) of 34%. We demonstrate experimentally that class B power amplifiers can achieve IM3 suppression comparable to class A, while providing approximately 10% improved power added efficiency.

High linearity GaN HEMT power amplifier with pre-linearization gate diode

A high linearity MMIC RF power amplifier is reported in the AlGaN/GaN HEMT technology. In order to obtain high linearity, a pre-linearization gate diode is added at the input to compensate for the nonlinear input capacitance C/sub gs/ of the GaN HEMT device. Another single-ended class B power amplifier without the gate diode is also designed for comparison. The circuit with the pre-linearization gate diode demonstrates at least 4dB improvement on 3rd order intermodulation distortion (IMD/sub 3/) performance over the one without the diode over the useful power range in two-tone measurement.

Simulations of high linearity and high efficiency of class B power amplifiers in GaN HEMT technology

We describe the design and simulation of highly linear and highly efficient common source class B power amplifiers. Efficient broadband class B push-pull amplifiers are not feasible at microwave frequencies as baluns with desired broadband even-mode impedance are unavailable. We find, however, that a single-ended class B amplifier with bandpass filtering has an equivalent efficiency and linearity. Simulations of class B designs predict a power added efficiency (PAE) of 48% with 40 dBc of third order intermodulation product (IMD3) performance when biased close to the pinch-off voltage.

InP HBT digital ICs and MMICs in the 140-220 GHz band

Well-balanced InP HBTs now have /spl sim/450 GHz cutoff frequencies and /spl sim/4 V breakdown. With such devices, 150 GHz digital circuits (static dividers) and 175 GHz amplifiers have been demonstrated. We discuss device requirements (scaling laws and scaling limits) for realizing transistors and both digital and analog/RF circuits at sub-mm-wave frequencies; the most critical limitations are metal/semiconductor contact resistivities and dissipated power densities. Given present contact performance and thermal design, 200 GHz digital technologies and 300 GHz power amplifiers are now feasible and will soon be realized.

Common base amplifier with 7-dB gain at 176 GHz in InP mesa DHBT technology

We report common base power amplifiers designed for 140-220 GHz frequency band in InP mesa double heterojunction bipolar transistor (DHBT) technology. A single stage common base tuned amplifier exhibited 7-dB small-signal gain at 176 GHz. This amplifier demonstrated 8.77 dBm output power with 5-dB associated power gain at 172 GHz. The two-stage common base amplifier exhibited 8.1 dBm output power with 6.35 dB associated power gain at 176 GHz and demonstrated 9.13 dBm of saturated output power. This two stage common base amplifier exhibited 10.3 dBm output power with 3.48-dB associated power gain at 150.2 GHz.

40 GHz MMIC power amplifier in InP DHBT technology

We report a 40 GHz MMIC power amplifier in InP DHBT technology that exhibits 14 dBm output power at 1 dB gain compression and 17 dBm saturated output power with 4 dB associated gain. The small-signal power gain is 6.8 dB, the input return loss is less than -20 dB and the output return loss is less than -6 dB. The peak power added efficiency is 12.5%.