The drift velocity of electrons and holes in silicon has been measured in a large range of the electric fields (from 3 . 102to 6 . 104V/cm) at temperatures up to 430 K. The experimental data have been fitted with a simple formula for the temperatures of interest. The mean square deviation was in all cases less than 3.8 percent. A more general formula has also been derived which allows to obtain by extrapolation drift velocity data at any temperature and electric field.

Electron and hole drift velocity measurements in silicon and their empirical relation to electric field and temperature

Microwave avalanche diodes of various types (IMPATT, TRAPATT, etc.) can generate power sufficient for microwave receivers and some transmitters. This brief review summarizes mechanisms of operation, power output, efficiency, noise, and some important features of design and fabrication.

Microwave avalanche diodes

This paper surveys the field of automotive radar and represents an expansion of a previous paper, "Automotive Radar-Problems and Promises" [1]. Both the roadside environment in which the car and driver operate and on-board physical environments in which the electronics must function are treated. Applications involving speed sensing, predictive crash sensing, obstacle detection, braking, and station keeping are addressed. Current radar system state of the art is reviewed. Considerations relating to target discrimination, weather penetration, and basic radar system parameters are covered. Modulation techniques for range determination are examined, and radar system configurations are discussed in an effort to identify the advantages and disadvantages of each. It is concluded that although considerable development work remains before radar becomes a practical automotive system, significant progress has been made.

Automotive radar: A brief review

A theoretical treatment is presented of some of the nonlinear properties of the IMPATT or Read avalanche diode, a negative-resistance semiconductor device that is now coming into wide-spread use for microwave oscillators and power amplifiers. Based upon the somewhat idealized Read model, this theory presents a qualitatively meaningful explanation of certain "parametric" effects that are often troublesome to the designers of amplifier and oscillator networks. First, an analytic treatment is given for frequency-conversion effects that appear when the device is strongly driven by one continuous signal, and simultaneously perturbed by a weak signal at another frequency or by noise. From this theory, stability criteria are derived for spurious oscillations of the "parametric" type which frequently appear in these devices under large-signal conditions. The noise-generation mechanism is reviewed, and it is shown that the noise is enhanced by strong signals and the spectral distribution is modified by frequency conversion. Some measurements of noise and frequency-conversion gain are presented which indicate substantial qualitative agreement with the theory.

Large-signal noise, frequency conversion, and parametric instabilities in IMPATT diode networks

This theoretical and experimental study was motivated by a specific need for a solid‐state microwave generator with an output efficiency exceeding 20% and focused on the properties of GaAs avalanche transit‐time devices. First, the dependence of the ionization rates and drift carrier velocities as a function of electric field and temperature is established. Then several methods of calculation, exact enough to take into account all the important efficiency‐limiting effects in the device, are discussed and used to derive theoretical figures for the efficiency of a GaAs IMPATT oscillator, special attention being given to the influence of the doping profile. Finally, the experimental study is described, including device realization and experimentally measured efficiencies, and a comparison between these and the calculated values is done. It is shown that the best calculated performances can reach 30% efficiency and that it is possible to obtain experimentally cw oscillation efficiencies exceeding 20% with GaA...

Theoretical and experimental study of GaAs IMPATT oscillator efficiency

This paper presents results on RF power output and efficiency of IMPATT oscillators obtained from a large-signal model of these devices. The results are obtained from a closed-form solution of the nonlinear equations describing a Read-type IMPATT diode. The closed-form solution is obtained by assuming a short transit time through the drift region compared to the RF period. The solution is used to obtain the large-signal diode impedance. The analysis shows that the power output of an IMPATT diode depends strongly on the series load resistance presented to the active part of the diode and that the change in diode reactance with increasing bias current also depends on the series resistance. Plots of power output as a function of frequency, bias current, and load resistance are presented. Frequency tuning of the oscillator through current variation is also discussed. Experimental results are presented and compared with the theoretical ones wherever possible. The results lead to an improved understanding of such oscillators and are extremely useful in optimizing their performance and determining their limitations.

A large signal analysis of IMPATT diodes

The characteristics of a coaxial avalanche diode oscillator circuit are calculated and compared with experimental results. The circuit admittance, as seen at the diode terminals, is calculated in the frequency domain for "optimally tuned" experimental conditions. The impulse response function of the circuit, as obtained from the transformed admittance, is used to obtain time-evolution solutions of the avalanche diode circuit system. The impulse response is more general than the previously employed differential equation characterization of a lumped element equivalent circuit. The simulation presented of the high-efficiency mode of oscillation allowed no adjustable parameters and is in excellent agreement with experiment. The simulation verifies the original TRAPATT [1] explanation for the high-efficiency mode of oscillation.

Characterization of avalanche diode TRAPATT oscillators

A large-signal model of the Read-type IMPATT diode has been used to analyze the frequency-mixing properties of the oscillating diode. The self-oscillating, two-port frequency converter is described in terms of its short-circuit admittance parameters. It is shown that in the proper circuit, parametric frequency conversion may result in a negative conductance at the input and output ports of the converter. Therefore, high-gain frequency conversion and parametric amplification are possible. Under some conditions, spurious oscillations may occur due to this negative conductance. Experimental circuits have been built which demonstrate conversion gain and parametric amplification and confirm qualitatively the theoretical results. It is also shown experimentally that some of the sideband noise of the IMPATT oscillator is due to low-frequency noise which is up converted from the bias circuit. Some of this noise can be eliminated by proper circuit design.

Frequency conversion in IMPATT diodes

The purpose of this paper is to analyze and characterize in some detail a 100-GHz double-drift IMPATT oscillator. The small-signal and large-signal behavior of the diode has been analyzed using a semiconductor-analysis computer program. It is suggested that previously reported experimental results have been achieved with the aid of second-harmonic tuning and that 150-GHz single-frequency operation is possible with the present diode structure.

W.J. Evans

Papers

A large signal analysis of IMPATT diodes

Characterization of avalanche diode TRAPATT oscillators

Frequency conversion in IMPATT diodes

Analysis of a 100-GHz double-drift IMPATT oscillator