An application of acoustic surface wave devices to communication receivers

In this paper we present a new acoustic surface wave phase-locked loop FM demodulator. This device uses the nonlinear coupling characteristics of an insulating piezoelectric to an adjacent semiconductor to generate an electric field in the semiconductor. The low-frequency voltage resulting from the spatial integration of the electric field along the semiconductor is used as the controlling voltage of a voltage controlled oscillator. The above device acts as a phase-locked loop of either the first order or the second order, depending on the amplitude of the input waves, the characteristics of the coupling device, and the integration length of the electric field in the semiconductor. Both theoretical and experimental results relating to the lock range, frequency tracking, and FM demodulation characteristics of the novel device are described.