Circuit for extending the dynamic range of an intermediate level selector

Abstract

An FM intermediate-frequency circuit into which there is integrated at least a limiter-amplifier (1A) and a phase-locked loop which contains a VCO (4). The limiter-amplifier also includes a level detector. The dynamic range of the level detector is expanded without having to use excessive limiter-amplifier amplification, which would cause oscillation problems, by placing in parallel with the limiter-amplifier (1A) at least a second limiter-amplifier (1B), in connection with which there is also a level detector. The level of the input signal of the second limiter-amplifier (1B) is dropped as compared with that of the first limiter-amplifier (1A) by means of a dividing circuit (R1, R2). The signals (1A, 1B) obtained from the level detectors are combined to form one level detection signal (ITOT). If the signals are in the form of current, the combining can be carried out directly by summing the signals.

Dependencies are inferred from the claim text.