| US 7,592,820 B2 | ||
| Isolated measurement circuit for sensor resistance | ||
| Kari-Matti Laakso, Pietarsaari (Finland); and Andreas Berts, Korsholm (Finland) | ||
| Assigned to ABB Oy, Helsinki (Finland) | ||
| Filed on Dec. 08, 2006, as Appl. No. 11/635,630. | ||
| Application 11/635630 is a continuation of application No. PCT/FI2005/000267, filed on Jun. 08, 2005. | ||
| Claims priority of application No. 20040802 (FI), filed on Jun. 10, 2004. | ||
| Prior Publication US 2007/0171055 A1, Jul. 26, 2007 | ||
| Int. Cl. G01R 27/08 (2006.01) | ||
| U.S. Cl. 324—713 [327/362] | 7 Claims |
| 1. A sensor resistance measurement circuit comprising:
a sensor connection that connects a resistive sensor to a voltage divider circuit,
means for supplying voltage to said voltage divider circuit, said means for supplying voltage comprising a non-inverting amplifier
stage for amplifying the sensor signal and a differential amplifier stage which, based on the difference between the amplified
sensor signal connected to its inverting input and a regulated reference voltage connected to its non-inverting input, is
arranged to supply the voltage to the voltage divider circuit,
said voltage divider circuit comprising:
a resistance in series with the sensor, and
means for filtering the voltage over the sensor resistance into a sensor signal, and
means for processing and further transmitting the sensor signal, wherein the means for supplying voltage to the voltage divider
circuit have been arranged to reduce the supplied voltage as a function of the sensor resistance.
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