Semiconductor Microwave Devices

Gunn Effect

Gunn Effect: In 1963, Gunn discovered the transferred electron effect which now bears his name. This Gunn Effect is instrumental in the generation of microwave oscillations in bulk semicon­ductor materials. The effect was found by Gunn to be exhibited by gallium arsenide and indium phosphide, but cadmium telluride and indium arsenide have also subse­quently been …

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Parametric Amplifier Types

Parametric Amplifier Types: The basic Parametric Amplifier Types have already been discussed in detail, but several others also exist. They differ from one another in the variable reactance used, the bandwidth required and the output frequency (signal or idler). Various other char­acteristics of Parametric Amplifier Types must also now be discussed, such as practical circuits, …

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Parametric Amplifier

Parametric Amplifier: The parametric amplifier uses a device whose reactance is varied in such a manner that amplification results. It is low-noise because no resistance need be involved in the amplifying process. A varactor diode is now always used as the active element. Amplification is obtained when the reactance (capacitive here) is varied electronically in …

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Varactor Diode Operation and Characteristics

Varactor Diode Operation and Characteristics: Varactor Diode Operation and Characteristics were first used in the early 1950s as simple voltage-variable capacitance and later for frequency modulation of oscillators. They thus represent a very mature semiconductor microwave art. As materials and construction improved, so did the maximum operating frequencies, until the stage has now been reached …

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Microwave Transistors

Microwave Transistors: Silicon bipolar transistors were first on the microwave scene, followed by GaAs field-effect transistors. Indeed, FETs now have noticeably lower noise figures, and in the C band and above they yield noticeably higher powers. A description of Microwave Transistors constructions and a discussion of their performance now follow. Transistor Construction: The various factors …

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