FM receiver including a phase-quadrature polyphase if filter

An FM receiver comprising:

• a signal path including, in cascade, an RF section, a first tunable mixer stage for a frequency conversion of a desired RF FM reception signal into a first intermediate frequency signal, an IF device and an FM demodulator, and means included in the signal path of the FM receiver for converting a single-phase signal in the signal path into a pair of signals in mutual phase quadrature, said pair of phase-quadrature signals being applied to in-phase and quadrature signal paths of the IF device, said IF device comprising a polyphase IF filter including first and second resonance amplifiers consecutively connected in cascade and incorporated in said in-phase and quadrature signal paths and having a resonance frequency and with a bandpass characteristic which is symmetrical around said resonance frequency, said polyphase IF filter being coupled to the FM demodulator, wherein each of said resonance amplifiers provides IF selectivity and each has a tuning control input for controlling the tuning thereof, an output of the cascade arrangement of the first and second resonance amplifiers being coupled via the frequency demodulator to a tuning control signal generating circuit, first and second outputs of said tuning control signal generating circuit being coupled to the tuning control inputs of the first and second resonance amplifiers, respectively, said tuning control signal generating circuit deriving for each resonance amplifier a tuning control signal from the output signal of the FM demodulator and thereby constituting first and second tuning control loops from the output to the tuning control input of the first and second resonance amplifiers, respectively, the open loop gain of each of the first and second tuning control loops being smaller than one, wherein the tuning control signal generating circuit comprises a cascade arrangement of first and second amplifier-limiters, outputs of which are coupled to the tuning control inputs of the first and second resonance amplifiers, respectively, the gain factor of each of the first and second amplifier-limiters being smaller than one.