초록 ▼

A digital pressure measuring system with nonlinear resolution is disclosed. The system includes a capacitive pressure transducer with a pressure variable sensing capacitor and a substantially invariable reference capacitor. The capacitors of the transducer are excited by out-of-phase signals and the

A digital pressure measuring system with nonlinear resolution is disclosed. The system includes a capacitive pressure transducer with a pressure variable sensing capacitor and a substantially invariable reference capacitor. The capacitors of the transducer are excited by out-of-phase signals and their outputs combined at a summing junction. The output of the summing junction controls the incrementation of a counter whose output is converted to a nonlinear negative feedback signal. A closed loop is formed by applying the feedback signal to the summing junction through a feedback capacitor. The counter is incremented in a direction to null the loop such that its output is representative of the measured pressure.

대표청구항 ▼

A capacitance to digital conversion system comprising: means for generating first and second alternating reference signals having a predetermined phase relationship therebetween; a primary sensing capacitor for measuring a condition driven by one of said reference signals; a digital-to-analog conver

A capacitance to digital conversion system comprising: means for generating first and second alternating reference signals having a predetermined phase relationship therebetween; a primary sensing capacitor for measuring a condition driven by one of said reference signals; a digital-to-analog converter driven by one of said reference signals for converting a digital signal to a first alternating feedback signal; means for generating a second alternating feedback signal having a predetermined phase relationship with the first alternating feedback signal; a feedback reference capacitor driven by one of said feedback signals; a feedback sensing capacitor sensitive to said condition driven by the other of said feedback signals; means, connected to the primary and feedback capacitors, for generating an error signal related to the sensed condition when currents through the primary and feedback capacitors are other than equal and opposite; and analog-to-digital converting means for converting said error signal to said digital signal wherein said digital signal is fed back to the digital-to-analog converter for conversion thereby to the first alternating feedback signal and is a measurement of said condition.