Analysis of a Sensor Based on an Injection-Locked Oscillator Driven by a Chirp Signal

A sensor based on an injection-locked oscillator driven by a chirp-signal source is presented. The system is accurately investigated with an envelope-domain semi-analytical formulation. The oscillator gets locked to the input source for a time interval that varies with the real and imaginary parts of the dielectric constant of the material under test. These data are retrieved by demodulating the oscillation frequency with the aid of a mixer and a low pass filter. A sensor based on this concept, operating at 2.3 GHz, has been implemented and characterized.