Analysis of Phase-Locked Loop System in Presence of Harmonic Interference

Dynamical characteristics of the phase-locked loop system are obtained using the harmonic balance method for the case of presence of the narrow-band (harmonic) interference apart from the useful signal. The analysis is performed with the arbitrary detuning between a carrier frequency and a controlled generator frequency (y = 0) and with the arbitrary detuning between a signal frequency and an interference frequency (d = 0). The case of (d = 0) is practically important because the d = 0 case is rarely encountered in practice. It is shown that the noise immunity of the phase-locked loop is reduced if the spectral constituents of the signal and the interference are on different sides with respect to the frequency of the controlling generator.