Oscillator circuit and method for measuring capacitance and small changes in capacitance
US5136262A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 13, 1991 |
| Grant date | Aug 4, 1992 |
| Priority date | — |
| Expiry date | Dec 13, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B5/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An improved oscillator circuit and method for measuring capacitance and small changes in capacitance is described. The circuit provides a digital output signal that has a frequency inversely proportional to the capacitance being measured, is substantially immune to stray capacitance, has low sensitivity to noise and temperature variations, is relatively simple and inexpensive to implement and provides a high precision measurement. One embodiment of the oscillator includes a capacitor to be measured, an integrator, a comparator, a resistive attenuator, a summing amplifier and a digital output circuit. A second embodiment of the oscillator further provides compensation for the non-linear response of a parallel plate capacitive transducer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.