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A pressure measurement device that has a digital clock circuit that provides an excitation clock and a control output. An integrator includes a switch controlled by the control output, an amplifier, and a pressure sensing capacitance coupled in an amplifier feedback path. The switch connects across

A pressure measurement device that has a digital clock circuit that provides an excitation clock and a control output. An integrator includes a switch controlled by the control output, an amplifier, and a pressure sensing capacitance coupled in an amplifier feedback path. The switch connects across the first pressure sensing capacitance. A reference capacitance that is insensitive to the pressure couples between the excitation clock and the amplifier input. An amplifier output represents the pressure.

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1. A pressure measurement device for sensing pressure in an industrial process, comprising:a digital clock circuit that provides excitation clock pulses, and control output pulses that are out of phase with the excitation clock pulses;a first integrator including a first switch controlled by the con

1. A pressure measurement device for sensing pressure in an industrial process, comprising:a digital clock circuit that provides excitation clock pulses, and control output pulses that are out of phase with the excitation clock pulses;a first integrator including a first switch controlled by the control output pulses, a first amplifier, and a capacitive pressure transducer fluidly couplable to the industrial process and having a first pressure sensing capacitance electrically coupled in an amplifier feedback path between a first amplifier output and a first amplifier input, the first switch connecting across the first pressure sensing capacitance; the amplifier providing an output representative of the pressure, and the control output pulses resetting the first amplifier output;a first reference capacitance that is insensitive to the pressure and that couples the excitation clock pulses to the first amplifier input; anda summing circuit receiving the first amplifier output that is reset by the control output pulses and a first reference potential; the summing circuit providing a summing circuit output representing the pressure. 2. The pressure measurement device of claim 1, further comprising:a first voltage divider coupling the excitation clock pulses to the first reference capacitor, the first voltage divider setting a first effective gage factor. 3. The pressure measurement device of claim 2, further comprising:a second voltage divider coupling the excitation clock pulses to a second reference capacitor. 4. The pressure measurement device of claim 2 wherein the first voltage divider comprises a laser trimmable resistor. 5. The pressure measurement device of claim 2 wherein the first voltage divider comprises a manually adjustable potentiometer. 6. The pressure measurement device of claim 1, further comprising:an adjustable potential circuit providing the first reference potential, the adjustable potential circuit setting a first effective gage factor. 7. The pressure measurement device of claim 6 wherein the adjustable potential circuit includes a laser trimmable resistor. 8. The pressure measurement device of claim 6 wherein the adjustable potential circuit includes a manually adjustable potentiometer. 9. The pressure measurement device of claim 6 wherein the adjustable potential circuit includes an analog switchable divider. 10. The pressure measurement device of claim 6 wherein the adjustable potential circuit includes a voltage controlled resistance. 11. The pressure measurement device of claim 6 wherein the adjustable potential circuit includes a capacitance divider. 12. The pressure measurement device of claim 6 wherein the adjustable potential circuit includes a programmable gain amplifier. 13. A pressure measurement device for sensing pressure in an industrial process, comprising:a digital clock circuit that provides an excitation clock and a control output;a first integrator including a first switch controlled by the control output, a first amplifier, and a capacitive pressure transducer fluidly couplable to the industrial process and having a first pressure sensing capacitance electrically coupled in an amplifier feedback path between a first amplifier output and a first amplifier input, the first switch connecting across the first pressure sensing capacitance; the amplifier providing an output representative of the pressure;a first reference capacitance that is insensitive to the pressure and that couples between the excitation clock and the first amplifier input;a summing circuit receiving the first amplifier output and a first reference potential; the summing circuit providing a summing circuit output representing the pressure; anda second integrator including a second switch controlled by the control output, a second amplifier, and a second pressure sensing capacitance coupled in a second amplifier feedback path between a second amplifier output and a second amplifier input, the second switch connecting acros s the second pressure sensing capacitance and the second amplifier output coupling to the summing circuit; anda second reference capacitance that is insensitive to the pressure and that couples between the excitation clock and the second amplifier input. 14. A differential pressure measurement device, comprising:first and second reference capacitances;a first integrator including a first pressure sensing capacitance, the first integrator having a first input coupled to the first reference capacitance, and a first integrator output that varies as a function of a first ratio of the first reference capacitance to the first pressure sensing capacitance;a second integrator including a second pressure sensing capacitance, the second integrator having a second input coupled to the second reference capacitance, and a second integrator output that varies as a function of a second ratio of the second reference capacitance to the second pressure sensing capacitance;a summing circuit receiving the first and second integrator outputs and providing a summing circuit output with an amplitude representing differential pressure between the first and second sensed pressures;a digital clock circuit coupling first and second excitation clocks to the first and second reference capacitors, respectively; andthe first ratio is matched to the second ratio when a first sensed pressure is substantially equal to a second sensed pressure over a pressure range of the differential pressure measurement device. 15. The differential pressure measurement device of claim 14 wherein the first reference capacitance is matched to the second reference capacitance. 16. The differential pressure measurement device of claim 14 wherein the first pressure sensing capacitance is matched to the second pressure sensing capacitance when the first sensed pressure is substantially equal to the second sensed pressure over the pressure range of the differential pressure measurement device. 17. The differential pressure measurement device of claim 14 wherein the first and second pressure sensing capacitances sense first and second absolute pressures, respectively. 18. The differential pressure measurement device of claim 14 wherein the digital clock circuit couples a reset clock to the first and second charge integrator circuits. 19. The differential pressure measurement device of claim 14 further comprising a sampling circuit that receives the summing circuit output and provides a two-wire, 4-20 mA analog transmitter output representative of the differential pressure. 20. The differential pressure measurement device of claim 19 wherein the digital clock circuit generates a sampling clock phase, and the sampling clock phase is coupled to the sampling circuit. 21. The differential pressure measurement device of claim 14 further comprising a sampling circuit that receives the summing circuit output and provides a digital measurement device output representative of the differential pressure. 22. The differential pressure measurement device of claim 14 wherein the first excitation clock is inverted relative the second excitation clock. 23. The differential pressure measurement device of claim 22 wherein the summing circuit comprises a differential amplifier, and the summing circuit output represents a difference between the first and second integrator outputs. 24. The differential pressure measurement device of claim 14 wherein the second excitation clock is out of phase with the first excitation clock. 25. The differential pressure measurement device of claim 24 wherein the summing circuit comprises a differential amplifier, and the summing circuit output represents a sum of the first and second integrator outputs. 26. The differential pressure measurement device of claim 14 wherein the summing circuit comprises a first input resistance coupled to the first integrator circuit, and comprises a second input resistance coupled to the second integrator circuit, and a resistance selected from the group of the first input resistor and the second input resistor is a trimmed resistance. 27. The differential pressure measurement device of claim 14 wherein the summing circuit couples directly to a two-wire, 4-20 mA analog transmitter output circuit that generates an transmitter output representative of the differential pressure.