Thermal Effects in the Operation of GaAs Transferred Electron Microwave Oscillators.
Interim technical rept.,
CORNELL UNIV ITHACA N Y SCHOOL OF ELECTRICAL ENGINEERING
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A conceptually simple, three part methodology is applied to the understanding of thermal effects in GaAs transferred electron microwave oscillators. The results are experimentally based, but given theoretical support. The use of a basic thermal model composed of a series of lumped thermal resistances produces two important transient and steady-state temperatures the temperature difference across the active layer, and the maximum active layer temperature. These are obtained from the input power and geometrical fabrication factors, and become the input parameters in a modification of the two-terminal device V-I characteristic. This characteristic is shown to be well described by three parameters which are obtained from an understanding of the internal diode physics. The parameters are the thermally modified peak and valley currents and low-field resistance of the diode structure. It will be shown that these three variables are sufficient to characterize the device, and when coupled to the RF circuit at the device-circuit interface, provide the desired knowledge of the observables of oscillator operation. These observables are peak and average power output, efficiency, frequency, stability, and a definition of the maximum bias and load. Author
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