# Second harmonic power generation in a Read diode and its dependence on the fundamental mode of oscillations

About: This article is published in Solid-state Electronics.The article was published on 1973-10-01. It has received None citations till now. The article focuses on the topics: High harmonic generation & Harmonic.

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TL;DR: In this paper, a semiconductor diode designed to operate as an oscillator when mounted in a suitable microwave cavity is described and analyzed, and it appears possible to obtain over 20 watts of ac power in continuous operation at 5 kmc.

Abstract: This paper describes and analyzes a proposed semiconductor diode designed to operate as an oscillator when mounted in a suitable microwave cavity. The frequency would be in the range extending from 1 to 50 kmc. The negative Q may be as low as 10 and the efficiency as high as 30 per cent. The diode is biased in reverse so as to establish a depletion, or space-charge, layer of fixed width in a relatively high resistance region, bounded by very low resistance end regions. The electric field has a maximum at one edge of the space-charge region, where hole-electron pairs are generated by internal secondary emission, or avalanche. The holes (or electrons) travel across the space-charge layer with constant velocity, thus producing a current through the diode. Because of the build-up time of the avalanche, and the transit time of the holes across the depletion layer, the alternating current is delayed by approximately one-half cycle relative to the ac voltage. Thus, power is delivered to the ac signal. When the diode is mounted in an inductive microwave cavity tuned to the capacity of the diode, an oscillation will build up. It appears possible to obtain over 20 watts of ac power in continuous operation at 5 kmc.

521 citations

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Bell Labs

^{1}TL;DR: In this paper, a simplified analytical method of calculating high-frequency, small signal negative resistance of p-n junctions in breakdown is presented, which can lead to microwave oscillations in Impact Avalanche Transit Time (IMPATT) diodes.

Abstract: A simplified analytical method of calculating high-frequency, small signal negative resistance of p-n junctions in breakdown is presented. The negative resistance can lead to microwave oscillations in Impact Avalanche Transit Time (IMPATT) diodes. The method consists in subdividing the entire space charge region into several uniform layers, each of which has constant avalanche multiplication (including zero), and connecting the analytical solutions of the successive layers (multiple uniform layer approximation). The simplest case of the approximation, in which there is only one constant-avalanche region and one or two avalanche-free drift regions, is used to investigate how the small signal characteristics change with width and position of the avalanche region. From the behavior of the small signal negative Q , it is expected that for low bias currents the oscillator performance improves when the avalanche region becomes relatively shorter, when its position moves from the center to the edge of the space charge region, and when the total space charge layer becomes wider. In materials with larger ionization rates, a negative resistance of a given quality ( Q ) is obtained at lower breakdown voltage and bias current.

47 citations

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Philips

^{1}TL;DR: In this article, the Fourier series representation of the transit-time oscillator of a large-signal transceiver is used to study the nonlinear operating characteristics of the transceiver, and the output power at the oscillation frequency is obtained explicitly in terms of diode and external circuit parameters.

Abstract: The nonlinear operating characteristics of the avalanche transit-time oscillator are studied by means of Fourier-series representation. For optimum operation, the oscillator must be designed such that start-oscillation conditions are satisfied simultaneously at the first and the second harmonic of the desired oscillation frequency. Under those conditions the oscillation frequency does not depend on the dc bias current; the signal level increases smoothly with bias current. For large signals, the diode exhibits negative resistance for frequencies substantially below the avalanche frequency; the oscillation frequency therefore may be below the avalanche frequency corresponding to the dc bias current required for large-signal operation. A condition for attaining large-signal operation is that the product of drift-zone capacitance and total load resistance must be small compared to the oscillation period; this condition also yields small starting currents. The output power at the oscillation frequency is obtained explicitly in terms of diode and external circuit parameters. The maximum attainable output power is limited by parasitic series resistance and by permissible RF voltage swing as compared to dc bias voltage. The best power-impedance product is obtained by choosing the transit angle equal to 0.74 π. In practice, it may be advantageous to choose a smaller value for the transit angle, in order that the tuning condition for the second harmonic may be more easily satisfied. The dc-to-RF conversion efficiency in principle is linearly proportional to the dc current density; the maximum efficiency again is limited by parasitic series resistance and by permissible RF voltage swing.

16 citations

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Bell Labs

^{1}TL;DR: In this article, the effect of second-harmonic tuning of IMPATT diodes is examined on a conceptual basis, and a simple interpretation of the "single-frequency" admittances of the diode may be made.

Abstract: Two-frequency operation of IMPATT diodes is examined in this paper on a conceptual basis. It is shown that a simple interpretation of the "single-frequency" admittances of the diode may be made. An equivalent circuit is presented which shows that the effect of second-harmonic tuning is to introduce a nonlinear resonance into the fundamental input admittance. This occurs when the external circuit admittance is tuned to the neighborhood of the "single-frequency" oscillator admittance of the diode at the second-harmonic. Computer calculations of the tuned-harmonic mode, with the diode embedded in the simplest possible RF circuit, are presented to demonstrate the effect.

6 citations