doppelsuperheterodyn - receiver circuit

摘要

The circuit includes a first local oscillator circuit (16) which controls a first local oscillation frequency (f1LO) dependent on a reference oscillation frequency (fREF) from a reference oscillator (20). A second local oscillator circuit (17) controls a second local oscillation frequency (f2LO) dependent on the reference oscillation frequency. A first mixer (12) mixes an HF signal with the first local oscillation frequency and outputs a first intermediate frequency (f1ZF). A second mixer (14) mixes the first intermediate frequency signal with the second local oscillation frequency and outputs a second intermediate frequency signal (2ZF). A flip-flop circuit (23) allows change of the first intermediate frequency while the frequencies of the HF signal, the reference oscillator and the second intermediate frequency remain unchanged.