Self-testing capacitive pressure transducer and method
US5377524A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 1992 |
| Grant date | Jan 3, 1995 |
| Priority date | — |
| Expiry date | Jun 22, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L27/007
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A high-performance switched-capacitor circuit for electronic read-out of a pressure sensor-based ultrasensitive microflow transducer. The microflow transducer uses a differential capacitive pressure sensor to measure flow. Read-out electronics associated with the transducer feature a clocking speed of 100 KHz and drive loads up to 35 pF. The read-out electronics include a high DC gain that nulls out stray input capacitance, which is beneficial for the multichip realization of the microflow transducer disclosed herein. The uncompensated linearity of the overall read-out electronics is 10 bits, and the pressure/flow resolution is 12 bits. An ultrasensitive membrane associated with the pressure sensor does not respond to a pulsed waveform for frequencies above 50 KHz. But for lower frequencies, it deflects in response to the time-average voltage applied across the capacitor plates of the pressure sensor. A self-test mode is provided which employs an extremely long pre-charge pulse. An integrated flowmeter package including transducer and circuitry, and a second circuit for extending the range of the microflowmeter circuitry are also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.