# Circuit dependence of fundamental power in a multifrequency Gunn oscillator

TL;DR: In this paper, the influence of second harmonic frequency termination on fundamental output power has been experimentally investigated for Gunn diodes generating simultaneous oscillations, and it was found that the fundamental power can be enhanced by a factor of 2 to 3 throughout the whole range of delayed domain mode by controlling the load parameter at the second-harmonic frequency.

Abstract: The influence of a second harmonic frequency termination on fundamental output power has been experimentally investigated for Gunn diodes generating simultaneous oscillations. It is found that the fundamental power can be enhanced by a factor of 2 to 3 throughout the whole range of delayed domain mode by controlling the load parameter at the second harmonic frequency. The experimental observations also suggest that the oscillation at any frequency may be suppressed by the proper positioning of tho Gunn diode in the co-axial resonator. A tentative theory to explain the increase of fundamental power over a wide range of frequencies is also presented, taking into consideration the fundamental and the harmonic circuit parameters for Gunn devices operated in a resonator.

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TL;DR: In this paper, the parametric interaction between the second harmonic and the fundamental frequency of X-band GaAs has been studied with the help of a coaxial resonator, and an increase in microwave voltage output of the fundamental has been observed by loading the device properly at the second harmonics.

Abstract: The parametric interaction between the second harmonic and the fundamental frequency of X-band GaAs Gunn devices has been studied with the help of a coaxial resonator. An increase in microwave voltage output of the fundamental has been observed by loading the device properly at the second harmonic. The reduced rise time of the switching transients has also been observed in the presence of second harmonic. These studies have been accomplished by measuring the device negative conductance as a function of RF voltage in the presence of the second harmonic.

1 citations

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TL;DR: In this paper, it was shown that a voltage waveform consisting of only a fundamental and second harmonic component could give efficiencies in the 20-28 percent range, as much as a factor of 3 larger than for a simple sinusoid.

Abstract: An examination of the problem of obtaining high-efficiency operation of a Gunn oscillator is given in this paper. The results are based on an assumed form of I-V characteristic of the Gunn diode, the ideal voltage and current waveforms being found for high-efficiency operation. The theory for a square wave of current through and voltage across the diode is worked out in detail and shown to predict the experimental results well. It is shown that a voltage waveform consisting of only a fundamental and second harmonic component could give efficiencies in the 20-28 percent range, as much as a factor of 3 larger than for a simple sinusoid. This is a reasonable approximation to the ideal voltage waveform, which is a half sinusoid of voltage. In this paper the charge and discharge time of the domain is neglected. An estimate of these times is given in the Appendix, and it is shown that the efficiency theory should be relevant to operation with diodes for which nL \gg 10^{12} cm-2. The theory may also describe certain types of "LSA mode" operation.

35 citations

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TL;DR: A tentative theory to explain the wide tuning range observed when Gunn specimens are placed in a suitable cavity resonator (in some cases almost one octave) is advanced in this paper, with limited confirmation of the theory.

Abstract: The general view is that the mechanism responsible for the Gunn effect must be similar to that proposed independently by Ridley and Watkins and by Hilsum several years ago. This theory is described and the experiments that have been reported to substantiate it indirectly are reviewed briefly.A tentative theory to explain the wide tuning range observed when Gunn specimens are placed in a suitable cavity resonator (in some cases almost one octave) is advanced. Some experimental results, giving limited confirmation of the theory are presented.

26 citations

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TL;DR: In this paper, the power output and efficiency of a cavity-controlled Gunn-effect oscillator were derived using Fourier analysis, where the applied bias voltage was equal to 1.9 times the threshold voltage and the load resistance was 8.6 times the low field resistance of the GaAs wafer.

Abstract: Using Fourier analysis, expressions are derived for the power output and efficiency of a cavity-controlled Gunn-effect oscillator. This treatment predicts an optimum efficiency of 7.2% when the applied bias voltage is equal to 1.9 times the threshold voltage and the load resistance is equal to 8.6 times the low-field resistance of the GaAs wafer. The theoretical results are compared with the experimental resulu report by Dow, Mosher and Vane.

24 citations

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TL;DR: In this paper, it was shown that the resonant-circuit behavior of a Gunn diode lies in the impedance presented to the diode at the second harmonic of oscillation.

Abstract: Theory and experiments are reported which show that a key to understanding the resonant-circuit behaviour of a Gunn diode lies in the impedance presented to the diode at the second harmonic of oscillation. This leads to an interpretation of the device as a parametric oscillator, and allows one to develop useful microwave circuits with an octave continuous-tuning range.

24 citations

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TL;DR: In this article, a detailed analysis of an experimental resonator as a basis for determining the output power and the tuning range of Gunn oscillators as functions of the fundamental resonant-load resistance is presented.

Abstract: A detailed analysis of an experimental resonator as a basis for determining the output power and the tuning range of Gunn oscillators as functions of the fundamental resonant-load resistance. Differing n/sub 0/L products (1.2 and 4.8x10/sup 12/ cm/sup -2/) lead to strikingly different results which are related to the delayed-and quenched-domain resonant modes, respectively. Variations of the second-harmonic frequency termination cause the fundamental output power of Gunn oscillators to change by a factor of up to 5, this change being accompanied by a frequency pulling of a few percent. From detailed impedance measurements it is concluded that the maximum fundamental power occurs if the second-harmonic circuit is tuned near an open-circuit resonance, the total circuit susceptance being somewhat capacitive.

12 citations