Post subject: question of design Posted: Tue
May 02, 2006 2:45 pm
Joined: Tue May 02, 2006
how can we design a automatic gain control circuit
Post subject: AGC amplifierPosted:
Tue May 02, 2006 6:26 pm
Joined: Wed Feb
22, 2006 3:51 pm
You need two things for an
1. A way to measure the signal strength, and
A way to vary the gain based on that measurement.
come in two varieties, feedback (closed-loop, more common) and feedforward
(open-loop, less common).
Signal strength measurement is often
done by rectification followed by low-pass filtering.
two major ways to vary amplifier gains:
1. Varying the operating
parameters of a BJT or FET
2. Using a FET or a PIN diode as a controllable
Within those two major ways are a large number of specific
approaches, depending on frequency, dynamic range, etc.