HIGHLY SENSITIVE CAPACITANCE MEASUREMENT FOR SENSORS

Very small capacitance changes from a capacitive transducer can be mea sured using a custom-designed signal-processing chip. The chip feature s a switched-capacitor integrator with chopper stabilisation to remove the effects of offset, 1/f noise and switch charge injection; the cir cuit is insensitive to stray capacitance. The achievement of high reso lution and low drift is demonstrated.