Oscillator for measuring temperature
US4719432A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 4, 1986 |
| Grant date | Jan 12, 1988 |
| Priority date | — |
| Expiry date | Aug 4, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K7/203
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A measuring oscillator for measuring temperature has an all-pass filter (1) which drives a current source (16) having a controllable amplification factor and a control element (17). The control element is connected to the control input of the current source (16) and controls its amplification factor in a manner such that the amplitude of the alternating voltage produced by the measuring oscillator assumes a constant value. The all-pass filter comprises a phase-determining bipolar circuit arrangement (10) comprising a voltage follower (12), whose input is connected to one terminal (9) of the circuit arrangement (10) and whose output is connected through an ohmic input resistor (13) to the inverting input of a first operational amplifier (14), which is fed back negatively through a measuring resistor (15) having a temperature-dependent ohmic resistance value. The output of the first op-amp also is connected through an ohmic resistor (41) to the one terminal (9) of the bipolar circuit arrangement. The non-inverting input of the first op-amp is connected to the other terminal (11) of the bipolar circuit arrangement. Small temperature variations sensed by the measuring resistor lead to …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.