Elimination of line impedance error in a three-wire probe interface
US4309653A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1980 |
| Grant date | Jan 5, 1982 |
| Priority date | — |
| Expiry date | Sep 25, 2000 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S323/909
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An RTD probe interface having a three-wire interconnection with a source excitation line, a source return line, and a sensed signal line, includes: an excitation signal source connected between the source excitation line and the source return line for providing an excitation current signal through the RTD; an amplifier having first and second signal inputs connected respectively to the source excitation line and the sensed signal line, for providing an output voltage signal at a magnitude proportional to the difference magnitude between the voltage signals present at the first and second amplifier inputs, and a bias signal source connected between the sensed signal line and the source return line for presenting a bias current signal to the sensed line, at a magnitude and phase equal to that of the excitation current signal, for providing equal line impedance dependent values in the voltage signals appearing at the first and second inputs of the amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.