UN APARATO RECEPTOR DE FRECUENCIA MODULADA.

摘要

An FM-receiver having an FM-channel successively comprising an RF-input stage and mixer stage (B), an IF-circuit (A) and a ratio detector (R). The ratio detector incorporates silicon detector diodes and a smoothing capacitor conductively connected to the detector diodes for a dynamic amplitude limitation of the ratio detector output signal in dependence on the amplitude of the ratio detector input signal. A bias voltage is applied to the silicon diodes to prevent the silicon diodes from being blocked at signals lower than the threshold voltage of the diodes. The bias voltage comprises an average noise voltage that is generated by amplifying a noise component of the FM signal, the noise component being present in the IF bandwidth. The average noise voltage is predominantly obtained by amplifying the noise produced within the IF-passband of the IF-input stage.