Grounded-Grid Radio-Frequency Voltage Amplifiers

Triode radio-frequency amplifiers have come into extensive use for medium-high-frequency applications. The use of triodes results from the reduced noise-equivalent resistance of a triode amplifier as compared to a multigrid-type amplifier tube. It is not possible with a triode to use conventional circuits with the input into the grid circuit and the output from the plate circuit because this connection results in excessive output to input feedback which produces regeneration and even oscillation. The grounded-grid amplifier circuit alleviates these difficulties by utilizing the grid as a shield between the input or cathode circuit and the output or plate circuit. Such a circuit exhibits certain peculiarities, particularly when several such stages are operated in tandem. Following is an analysis of the performance of several types of grounded-grid radio-frequency amplifiers.