Injection-Locked-Oscillator FM Receiver Analysis

It is well known that a conventional phase-locked loop can be used as a frequency modulation receiver.1-3 It is perhaps less well known that the locking performance of the phase-locked loop and the injection-locked oscillator are described by the same differential equation.4 These two facts suggest that an FM receiver using an injection-locked oscillator is possible. It is. And such a receiver is described here. The principle of operation of the two receivers is the same but there are important practical differences. The baseband bandwidth of the phase-locked-loop receiver is limited by delay in the feedback loop to frequencies of about 1 MHz. The baseband bandwidth of the injection-locked-oscillator FM receiver can be as large as half the locking bandwidth of the injection-locked oscillator. With existing solid state oscillators such as the tunnel diode, locking has been achieved with bandwidths in excess of 200 MHz, 5 indicating that operation with basebands of about 100 MHz is possible. This type of receiver is not used in present day systems and there has been little or no interest in it for about 20 years. 0-10 Woodyard 7 1653