Replica bridge sensing circuit
US4038609A · kind A · utility
Inventor
Key dates
| Filing date | Jul 19, 1976 |
| Grant date | Jul 26, 1977 |
| Priority date | — |
| Expiry date | Jul 19, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/104
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A replica bridge sensing circuit, comprising an amplifier having inverting and non-inverting inputs, which are symmetrically connected to a generator through a bridge circuit that has replica elements in corresponding branches. Replica elements are defined as circuit components which because of identity of the manufacturing process, are nearly identical both physically and electrically. A nearly balanced replica bridge, so connected, between the input and the output of such an amplifier forms a Replica Bridge Oscillator (RBO) circuit. Non-linear elements are included in the oscillator circuit to stabilize the amplifier output amplitude and the phase angles between the inputs and output. Replica Bridge Oscillator operation is substantially immune to changes in environmental conditions and to changes in the power supply voltages. With replica sensor elements used in corresponding branches, the Replica Bridge Oscillator is a sensing circuit particularly well adapted for use in detection of small sensor impedance variations. When utilized for metal detection, such a sensing circuit exhibits improved sensitivity and stability over existing detection circuits and is particularly adapted …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.