Patent ID: 7176726

Claim:
A loss-of-signal detector, comprising: (a) an amplifier with a high gain state and a low gain state; (b) a comparator coupled to an output of said amplifier and to a source of a reference signal, an output of said comparator for indication of a loss-of-signal at an input of said amplifier; (c) a rectifier and a low-pass filter coupled between said comparator and said output of said amplifier; and (d) a gain control coupled from the output of said comparator to said amplifier; (e) wherein (i) when said amplifier is in said high gain state and a signal at said output of said amplifier falls below said reference signal, said gain control switches said amplifier into said low gain state and (ii) when said amplifier is in said low gain state and a signal at said output of said amplifier rises above said reference signal, said gain control switches said amplifier into said high gain state.