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Gallium arsenide double-drift Read IMPATT diodes are under development for use at 40 GHz. Such diodes have offered higher efficiency and average power than silicon diodes. The advantage may be ascribed to both the intrinsic properties of GaAs and the more complex doping structures used. In this paper, we describe diodes which give 16 W peak power at efficiencies up to 15%. Duty cycles between 5% and 30% have been employed at various peak power levels. The techniques used to design the double Read doping profiles and their resulting microwave properties are discussed. The characteristics of the Kurokawa test circuit are described in terms of measured S-parameters.

Excellent noise (0.41 dB minimum noise figure with 11.5 dB associated gain at 18 GHz) and linearity (third order intercept point of 37.6 dBm at 42.5 mW DC power giving a linearity figure of merit (LFOM) of 137) have been obtained for InAlAs-InGaAs metamorphic HEMTs on a GaAs substrate. These devices have been used to design and fabricate microwave and millimeter wave amplifiers. Amplifier results are presented.

The authors report the third-order intermodulation distortion and phase deviation of 1.2-mm periphery double pulsed doped pseudomorphic high-electron-mobility transistors (HEMTs) at high levels of power and efficiency. A device tuned for single-tone power-added efficiency (PAE) of 59% with 0.87-W output power and 10.4 associated gain at 10 GHz could provide two-tone PAE of 50% with -19 dBc IM3/C and 0.30 W/tone. Single-tone phase deviation never exceeded 18 degrees from small signal with a phase deviation slope less than 3 degrees /dB. These measurements compare favorably to those of reported GaAs-based devices with comparable output power. A dry etched double recess structure was incorporated in the device for obtaining high reverse breakdown voltage and therefore high efficiency. >

A number of GaAs transistors were evaluated as passive mode mixers with a 10 GHz RF and 2 GHz IF. Both single-tone and two-tone performance were measured for an ion implanted MESFET, spike-doped PsMESFET, a power PsHEMT and a npn power HBT. All were shown to have a substantially lower distortion than a comparable diode mixer. One transistor, the spike-doped PsMESFET, has a relative third order intercept point 20 dB higher than that of a diode mixer. >

A technique has been developed for modeling intermodulation distortion of GaAs MESFETs using pulsed I-V drain characteristics. The technique involves measuring the drain I-V characteristic using short drain and gate pulses from a DC operating point. This pulsed I-V characteristic is used to model the nonlinearity of the drain current source. In addition, S-parameters measured about the DC bias point are used to model the gate capacitance nonlinearity. These nonlinearities are combined into a single model, and the harmonic balance method is used to simulate intermodulation performance. This technique has been used to simulate the third-order intermodulation distortion of a spike-doped MESFET and to investigate sensitivities of source and load impedance and device nonlinearities on intermodulation performance. >

A highly linear GaAs MESFET has been developed. This device incorporates a spike profile in its active channel and was designed specifically for linearity. A third-order intercept (IP3) and a 1 dB compression power of 43 dBm and 19 dBm, respectively, have been measured on a 400 mu m device at 10 GHz. The difference between these two numbers, 24 dB, is the largest yet reported for a MESFET. This device also dissipates only 400 mW of DC power yielding a linearity figure-of-merit (IP3/P/sub DC/) of 50. >

We report design, fabrication, and test of a monolithic GaAs IC implementing a broadband optically-driven digital/analog RF interface. The circuit operates in an asynchronous mode to detect AM digital and RF on a single optical fiber input, control RF level, and transmit the RF to the output. >

A new method is given for determining the electrical series resistance of an IMPATT diode. The measurement is based on observation of the oscillation threshold bias current for a diode in a standard circuit. The method is applied to GaAs diodes near 40 GHz. The values obtained are used to quantitatively explain other performance characteristics of the diodes.

High-performance GaAs double-drift Read IMPATT diodes have been demonstrated at 60 GHz. 1.24-W CW output power at 11.4-percent dc to RF conversion efficiency was obtained with a junction temperature rise of 225°C. The doping profiles and test circuits have not yet been optimized and we expect that still higher power and efficiency should be achievable.