Wide-Range Automatic Gain Control Circuit for Superregenerative Amplifiers

摘要

An automatic gain control (AGC) circuit for a pulsed superregenerative amplifier was devised, which features what is believed to be a novel principle of operation, that is, gain control by control of the width of the keying pulse. This principle converts the superregenerative amplifier into a very stable device, which will operate in the linear mode and will permit linear detection of signal modulation for a wide range of input signal levels. Satisfactory AGC action has been experimentally demonstrated for input signals having a dynamic range as great as ninety decibels. With this type of AGC the bandwidth and shape of the curve of frequency response to input signals and the shape of the gate rejection characteristic are independent of input signal level. This method of AGC is very flexible in that it appears to be readily adaptable to various types of oscillators and various frequency ranges. This versatility has been demonstrated by its application to grid-pulsed and plate-pulsed oscillators at 150 megacycles and to a klystron-type oscillator at X-band. Another feature which may be of importance is the fact that the AGC control characteristic is naturally a logarithmic function. Numerous graphs are given in the report relating to AGC characteristics, frequency response, and gate resolution of superregenerative amplifiers using the various types of oscillators which were tried with this AGC circuit. (Author)