Noise-Free Analysis of a Tracking Filter FM Demodulator

The genesis and development of tracking filter structure arising out of a phase-plane study of the forced behavior of a general nonlinear second-order differential equation describing narrowband filters is discussed. By appropriately choosing the functional form of the feedback coefficients, two feasible filter structures for FM demodulation are obtained and their performance is compared in terms of tracking range, demodulation linearity, and steady state amplitude and phase response. Simulation study further supplements these results.