Automatic gain control circuit and method for direct sequence spread spectrum receiver

摘要

An automatic gain control circuit (3) for a direct sequence spread spectrum receiver. A discrimination unit (10) generates a discrimination signal error from received in-phase and quadrature base band signals, whilst multiplication unit (16) multiplies the discrimination signal error by a first loop gain constant during signal acquisition and a second different loop gain constant during signal tracking. A recursive integrator (22) then acquires an integrated AGC value from the multiplied discrimination signal error. By using two different values of loop gain, the circuit is able to alternate between a "fast mode" during signal acquisition, and a "slow track" mode during signal tracking.