Automatic Gain Control Amplifier

摘要

By combining analog and digital circuitry, a fast Automatic Gain Control (AGC) capable of amplifying the first instant of a received signal burst has been built. The AGTC provides a constant gain for the duration of an input signal's pulse length. To determine and apply the gain to the first instant of the signal, the analog signal pulse is digitized by an analog-to-digital (A/D) converter and then delayed in RAM while the signal level is detected and the necessary gain determined. After the gain is applied to the digital signal, the signal is returned to analog form by a digital-to-analog circuit. The dynamic range of the signal is compressed by the AGC circuitry so that the signal can be recorded for future processing. The system, for which the AGC is intended, compares the phase of several received signals. Therefore, any distortion between channels must be minimized. Signals as low as 40 mvolts peak can be digitized and reconstructed without significant loss of phase information between channels. (Less than 1 microsecond difference between any two channels.)