Effect of unequal ionization rates on GaAs IMPATT device admittance

The effect of the recently reported unequal ionization rates in GaAs on small signal IMPATT device admittance has been calculated and is compared with equal ionization rate results at room temperature. The ionization rate effect on the static breakdown voltage has also been obtained.     

Effects of ionization rates on IMPATT device admittance

The significance of using different ionization rates on the operating characteristics of Si IMPATT devices is examined. The dc breakdown and small-signal results of IMPATT devices at room temperature are presented. Numerical results for p⁺nn⁺as well as the complementary n⁺pp⁺Si diodes in the millimeter-wave frequency range and at different current densities ranging from 2500 to 10 000 A/cm²are given. It is shown that large differences in some important device parameters are obtained, depending on the ionization rates employed.     

Measurement technique for largesignal admittance of IMPATT diodes

A method is described for determining the large-signal admittance of an IMPATT diode from reflection-coefficient measurements at the output of a well-characterised IMPATT oscillator/amplifier circuit. Measurements at 10 GHz are presented and compared with the computed performance for the diode.     

High-efficiency X-band GaAs IMPATT diodes

Epitaxial GaAs diodes have been fabricated giving 65¹mW CW output power at 10 GHz under room temperature operation. A dc to RF efficiency of 10.1 percent was obtained from a diode operating CW while the measured output of another diode was over 20 mW for 3 mA dc with 70-volt biasing.     

Millimeter-wave GaAs read IMPATT diodes

We have designed, fabricated, and evaluated gallium arsenide Read IMPATT diodes for Ka-band (36-38 GHz)operation. The devices were packaged units intended for manufacturability and high yield. Oscillator output power as high as 710-mW CW was obtained at 9-percent efficiency. This paper describes design and fabrication techniques employed and discusses the potential and limitations of such devices.     

High-efficiency proton-isolated GaAs IMPATT diodes

The fabrication and c.w. operation of planar proton-isolated diffused junction and Schottky-barrier GaAs IMPATT diodes are described. The diodes have shown a maximum efficiency of 13.5% and output power of 315 mW in the Q band. Planar diodes appear to be superior to mesa devices formed from identical material.     

Millimeter-wave GaAs Schottky-barrier IMPATT diodes

Recent experimental observations on a Schottky-barrier GaAs IMPATT diode for F-band operation are presented. The diode slices were thinned to 10 to 20 µm by removing the substrate by precision polishing. Output power of 304 mW at 50 GHz with 4.58 percent efficiency was observed. The highest efficiency was 4.72 percent at 55 GHz.     

High-efficiency monolithic GaAs IMPATT diodes

Impedance-matching circuits were integrated on the same chip as the IMPATT diodes to produce monolithic impatt diodes for millimetre-wave applications. A drastic reduction of device-to-circuit parasitic elements was achieved by placing the external circuitry very close to the device. Oscillators fabricated in this fashion gave the highest efficiencies reported so far in the 30?35 GHz range with 28% conversion efficiency using hybrid-Read structures.     

High Power GaAs IMPATT Amplifier

10-W p-n junction GaAs IMPATT diodes with MTTF more than 10/sup 6/ h, have been developed. Using these diodes, amplifiers of 5-W output power, 10-dB gain, 17-percent efficiency, 150-MHz bandwidth, and 80-dB signal-to-noise ratio (S/N ratio) have been constructed.     

Q band GaAs Schottky-barrier IMPATT

Microwave power at Q band is reported from GaAs Schottky-barrier avalanche diodes. A nickel-contacted epitaxial GaAs structure in a flipped mesa configuration was used. In a Q band waveguide cavity, 0.5 W was obtained at 26.7 GHz using a pulsed voltage source.     

Millimeter-wave GaAs distributed IMPATT diodes

Millimeter-wave oscillations were obtained in distributed GaAs IMPATT diodes prepared by molecular beam epitaxy (MBE). Both single-drift-region and double-drift-region structures were used to fabricate various length devices, up to 1.25 mm, to investigate oscillation frequency dependence on device length. Output power levels of 1.5 and 0.5 W were obtained at 22 and 50 GHz, respectively, using 500-ns pulses. The highest frequency of oscillation observed was 89 GHz.     

High-efficiency V-band GaAs IMPATT diodes

Double-drift GaAs IMPATT diodes were designed for V-band frequency operations and fabricated using molecular-beam epitaxy. The diodes were fabricated in two configurations: (a) circular mesa diodes with silver-plated (integrated) heat sinks; (b) pill-type diodes bonded to diamond heat sinks. Both configurations utilised a miniature quartz-ring package. Output power greater than 1 W CW was achieved at V-band frequencies from diodes on diamond heat sinks. The best conversion efficiency was 13.3% at 55.5 GHz with 1 W output power.     

Efficient p-type Si IMPATT diodes for V-band frequencies

p-type single-drift IMPATT diodes for V-band frequencies were fabricated by a single diffusion process. The diodes were packaged on a copper heatsink using quartz standoffs and investigated in a resonant cap waveguide structure. The maximum CW output power is 0.5 at 68 GHz with an efficiency of 8.7%     

Comparison of high-efficiency GaAs IMPATT designs

Calculations of maximum generated r.f. powers are presented for GaAs single-drift Read, double-drift Read and hybrid Read structures at 10 GHz. The single-drift Read diode gives the highest output power in c.w. applications, and the double-drift design is superior in pulsed operation.     

X-band MIC GaAs IMPATT amplifier module

A compact (2.0 by 1.6 in), light weight (2.1 oz), microwave integrated circuit (MIC) GaAs IMPATT amplifier module having 3.6-W pulsed output power with a gain of 22.5 dB over the 9.2-9.8 GHz band has been developed for phased array radar applications. The design goal for the module was 4-W pulsed output power with 23-dB gain over this frequency band. The module has been operated over a wide range of pulse lengths (200 ns-50 /spl mu/s) and duty factors (0.5-40 percent) with outstanding pulse fidelity. The totally integrated module consists of three IMPATT reflection amplifier stages in cascade with input and output isolators and a transmit/receive switch. Each amplifier stage has an independent hybrid thin film constant current pulse modulator. The design considerations of the essential components for final module integration, and the microwave performance characteristics are presented.     

GaAs IMPATT diodes for 60 GHz

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.     

A GaAs distributed IMPATT diode amplifier

Stable microwave amplification has been obtained in GaAs distributed IMPATT (DIMPATT) diodes by the use of shorter than resonant length devices and appropriate input/output port terminations. CW output powers of 2 W were achieved at 9.5 GHz with 10-dB gain.     

140 GHz GaAs double-Read IMPATT diodes

CW GaAs double-Read IMPATT diodes for D-band frequencies are designed and tested. For reproducible RF impedance matching, the module encapsulation technique is applied. Ohmic losses of the active device are reduced by a titanium-Schottky contact instead of an alloyed ohmic n ⁺-contact. At 144 GHz 100 mW RF power with a conversion efficiency of 5% is realised     

GaAs 50 GHz Schottky-barrier IMPATT diodes

Technological improvements have been made to realise high-efficiency GaAs Schottky-barrier IMPATT diodes in the 50 GHz band. Efficiency and output power have been increased by a factor of 1.5 over previous best results. Efficiency as high as 11.0% at 51 GHz and an output power of 420 mW at 53 GHz have been obtained.     

Design considerations of high-efficiency GaAs IMPATT diodes

The efficiency and noise of p⁺n1n2n⁺GaAs IMPATT diodes have been studied as functions of the doping ratio n1/n2(when n1=n2we have a conventional abrupt p-n junction). For n1/n2>1 there are tradeoffs between efficiency and noise. At 12 GHz, for example, with a ratio of 4 the efficiency is 25 percent and the noise measure is 3 dB higher then that of a conventional IMPATT diode.