STABILITY ANALYSIS OF AN AUTONULLING AC BRIDGE FOR USE WITH SILICON-BASED SENSORS

A novel circuit incorporating integral feedback to automatically null an ac bridge is analyzed and discussed. Stability of the feedback sche me is examined by linearizing the system near the critical point (null ) of the bridge using a standard perturbation method. Solutions of the nonlinear coupled differential equations that describe the operation of the autonulling ac bridge were obtained by numerical integration. A prototype was constructed using integrated circuits and discrete comp onents to measure the transient response; test results of the circuit from transient impedance changes are compared to the time-dependent nu merical solutions.