Pressure sensitive transducer circuits

摘要

This relates to a circuit for delivering a linear voltage (VP) which is inversely proportional to the capacitance of a pressure sensitive capacitive transducer. A constant current IO is alternately switched into a reference capacitor (CR) and the transducer capacitor (CP). When the voltage across CP reaches VP, a flip-flop is toggled to direct current to CR. When the voltage across CR reaches a reference voltage (VR), the flip-flop is again toggled directing current to CP. A duty cycle detector charges integrator capacitors until the feedback voltage VP is such as to render equal the charging times of CP and CR.