AM receiver

摘要

AM receiver comprising a tuning oscillator (T0), a first phase detector (PD1) and a first loop filter (LP1) successively arranged in a first phase control loop. The tuning oscillator (T0) is synchronized with a reference oscillator (VCX0) coupled to the first phase detector (PD1) and applies a mixing frequency to a mixer stage (M) for conversion of a received AM signal into an IF-AM signal. The mixer stage (M) is coupled to an AM demodulator (SD) for demodulation of the base-band modulation signal. The reference oscillator (VCX0) is controllable and is disposed between a second loop filter (LP2) and a second phase detector (PD2) of a second phase control loop coupled to the mixer stage (M) for applying a local detection carrier synchronized with the IF-AM signal carrier to the AM demodulator (SD). The second loop filter (LP2) applies a control signal to the reference oscillator (VCX0) and is connected through a coupling circuit (C) to a control input of the tuning oscillator (T0) for a negative feedback of the control signal of the reference oscillator (VCX0) to the tuning oscillator (T0).