X-band silicon double-drift IMPATT diodes using multiple epitaxy

Silicon double-drift IMPATT diodes made by consecutive epitaxial deposition have been fabricated successfully. Output power in excess of 1.7 W with 10-percent efficiency was obtained at X band.     

High-power pulsed GaAs double-drift hybrid-read impatt diodes for X-band

Gallium-arsenide double-drift hybrid-Read Impatt diodes have been developed to deliver high peak and average powers in X-band. A peak power output of 35 W with 20% efficiency has been obtained at 8.3 GHz for 20% duty cycle. Peak power output of 32 W with 20% efficiency has been obtained at 8·6 GHz for a 25% duty cycle. Peak power output of 26 W with 21.5% efficiency has been obtained at 8.6. GHz for 33% duty cycle.     

Transient temperature behavior in pulsed double-drift IMPATT diodes

The temperatures in a pulsed double-drift IMPATT diode are calculated as a function of position and time by a finite difference calculation using the alternating direction algorithm. The results are given as a function of pulse length and duty factor for a typical double-drift diode designed to operate near X band. Techniques are described for choosing spatial meshes and time integrals which vary with position and time in a way that minimizes computation time. Numerical results are chosen to illustrate the distribution of temperature within the diode at different times during the pulse, the effect of a temperature-dependent breakdown voltage upon radial temperature distribution, and the interplay between the short thermal-diffusion times within the GaAs diode and the long times associated with the slow heating-up of the heat sink at great distances. An extended definition of thermal resistance for pulsed diodes is introduced and the implications upon reliability are discussed.     

Epitaxially grown double-drift silicon IMPATT diodes at 60 To 90 GHz

The characterisation of successively grown n- and p-type epitaxial layers suitable for double-drift 60-90 GHz oscillators is described. Microwave results are reported, and include 0.35 W with 9.2% efficiency at 70 GHz.     

Large-signal analysis of Lo-Hi-Lo double-drift silicon IMPATT diodes at 50 GHz

Large-signal analysis of a lo-hi-lo double-drift silicon IMPATT diode at 50 GHz shows that the device is capable of output power of 1.1 W and efficiency of 20 percent for a device area of 2 × 10^-5cm²at a dc biasing current density of 12 kA/cm²and ac voltage amplitude of 12 V. It is also found that, both output power values and efficiencies decrease with increasing enhanced leakage current.     

Design considerations of high-efficiency double-drift silicon IMPATT diodes

High-efficiency silicon double-drift IMPATT diodes with a low-high-low doping profile structure are proposed. Devices with efficiencies of 25 percent for 12 GHz, 24 percent for 18 GHz, and 19 percent for 50 GHz, are Predicted by numerical calculations.     

High-power operation mode of pulsed IMPATT diodes

Pulsed silicon double-drift IMPATT diodes that yield 42 W at 96 GHz are discussed. This is about twice the value reported previously. Owing to the considerable input powers (≈500 W), these diodes are mounted on diamond heat sinks. Because of the strong carrier injection, the field distribution in the diode is similar to that in a p-i-n diode. An attempt is made to explain the results using T. Misawa's (1966) p-i-n type theory. The large-signal; avalanche resonant frequency is close to the operation frequency. Conventional Read-type theory fails to explain these results because of the current densities employed in the experiments     

High-power c.w. transferred-electron oscillators

C.W. operation of high-power transferred-electron oscillators (t.e.o.s) is described. A maximum power output of 0.78 W at 8.7 GHz with an efficiency of 2.5% was obtained. This is believed to be the highest c.w. power output reported to date for a single t.e.o. in this frequency range. This high-power output is attributed to improved fabrication technology leading to a thermal resistance of only 8 deg C/W for a 0.015×0.015 in chip.     

Indium-phosphide c.w. transferred-electron amplifiers

J band c.w. low-noise indium-phosphide reflection amplifiers are described. An integral-heatsink technology has resulted in devices that can be operated c.w. at high bias levels. C.W. noise figures as low as 10.7 dB have been obtained at 14 GHz, and voltage-gain-bandwidth products of 3.1 GHz have been obtained. Measurements of impedance, noise and the temperature sensitivity of the gain are presented.     

Recent advances in device processing and packaging of high-power pulsed GaAs double-drift IMPATT's at X-band

High-power multimesa GaAs hybrid double-drift IMPATT's have been developed for pulsed operation at X-band. The diodes are fabricated from GaAs material grown by a novel "infinite" solution liquid phase epitaxial process. The use of specialized rapid thermal processing and packaging techniques has enabled the fabrication of high-power IMPATT oscillators that have delivered peak output powers of over 40 W with 20-percent efficiency under pulsed RF operation at X-band frequencies. The diodes are constructed with an integral heat sink and bounded with a Au-Sn eutectic solder in a microwave package.     

High-power pulsed beam-lead IMPATT diodes for millimetre waves

IMPATT diodes with technologically integrated beam-leads were fabricated. Since no diode bonding is required, a total diode thickness of less than 2 ?m can be realised reproducibly. With optimum device packages, peak pulse output powers of more than 10 W at 70 GHz have been achieved from silicon single-drift IMPATT diodes.     

Shifting of the peak generation rate in double-drift silicon IMPATT diodes

In double-drift (DD) silicon IMPATT diodes, it is observed that the peak generation rates of both carriers (electrons and holes) lie within the n side. The shifting is due to the unequal ionization rates for electrons and holes in silicon. By neglecting the reverse saturation current, a simple analytical expression for the location where the peak generation occurs is derived. This simple result may be useful for the design of double-drift as well as complementary single-drift IMPATT diodes.     

Frequency/temperature relationships of c.w. IMPATT diodes

Some measurements of the relationship between frequency and ambient temperature for c.w. IMPATT diodes are reported. Several diodes have been characterised between 9 and 13 GHz for various bias and coupling conditions. An interpretation of the results is presented on the basis of several simple models. Reasonable agreement with experiment is observed, considering the limitations of the models.     

InP pulsed and c.w. millimetre-wave oscillators

InP 3-level oscillators have been operated under c.w. and pulse-bias conditions in the frequency range 30?40 GHz with power outputs of up to 7.5 mW and 240 mW, respectively. C.W. power is also obtained at frequencies above 40 GHz.     

Silicon IMPATT cascaded amplifier: 6 W (c.w.) at 9.6 GHz

A compact silicon IMPATT 4-stage coaxial amplifier has given 6.3 W (c.w.) with a power gain of 28 dB and an instantaneous bandwidth (?1 dB) of 200 MHz centred at 9.6 GHz. A gain ripple of less than 0.2 dB and phase deviation from linearity of ±3° across a 30 MHz bandwidth slot was obtained at the full rated output power. The overall efficiency was 4.5%. Commercial devices and circulators were used throughout the unit and the power in the final stage was obtained by combining the available powers from four separate devices. Particular attention was paid to the circuits to reduce the onset of spurious oscillations under large-signal conditions.     

High-power high-efficiency c.w. Gunn oscillators in X band

Gunn oscillators on diamond heat sinks have produced up to 780 mW c.w. with 5.1% efficiency at 9.9 GHz. The devices were operated in full-height waveguide cavities. Similar devices on copper have produced up to 700 mW with 4.1% efficiency and typical powers of 600 mW with efficiencies of 3.9%. The effect of varying the 2nd-harmonic loading on devices mounted in fully-reduced-height waveguide has also been investigated, but no enhancement in output power at the fundamental frequency was observed.     

Operation of avalanche diodes as c.w. amplifiers at fractions of the transit frequency

The operation of an avalanche diode as a self-pumped parametric amplifier at low current densities is described. Gains of up to 15 dB are obtained at frequencies of the order of one-quarter of the transit frequency, while the diode is providing its own pump at three-quarters of that frequency. A theory based on utilising a Read-diode approximation to the device is used to calculate the response of such an amplifier, and good agreement is found for both the gain and saturation characteristics of the device.     

Computer studies on the widening of the avalanche zone and the decrease in efficiency of silicon X-band symmetrical double-drift impatt diodes at high current densities

A computer study of the field and current profiles of silicon X-band symmetrical d.d.r. impatt diodes is presented. The results show that there is considerable widening of the avalanche zone at high values of current density. This causes a sharp fall in the efficiency of the device at high current density after reaching a maximum.     

High-power pulsed fibre source at 1567 nm

A pulsed fibre source based on an Er/Yb-codoped fibre amplifier producing 1567 nm-wavelength, spectrally narrow, /spl sim/2 ns pulses with maximum energy 303 /spl mu/J, average power of up to 12 W, and peak power in excess of 130 kW is reported.     

Effect of p-n junction overheating on degradation of silicon high-power pulsed IMPATT diodes

The thermal limits of the two-drift impact avalanche and transit-time (IMPATT) diode operating in the pulsed mode in the 8-mm wavelength region with a microwave power as high as 30–35 W have been estimated. It is shown that p-n junction overheat at an operating pulse length of 300 ns and a supply current amplitude of 11.3–15 A amounts to 270–430°C relative to an ambient medium. The temperature limit of junction overheating, above which IMPATT diodes rapidly degrade, was determined as 350°C. The presented results of X-ray phase analysis and depth profiles of Au-Pt-Ti-Pd-Si ohmic contact components confirm thermal limits of the IMPATT diode operating in the pulsed mode.