Oscillator-based interface for measurand-plus-temperature readout from resistive bridge sensors

V. Ferrari, D. Marioli, A. Taroni

Research output: Contribution to journalArticlepeer-review

Abstract

A signal conditioning circuit based on a relaxation oscillator is proposed for use with resistive bridge sensors. The circuit provides a rectangular-wave output whose frequency is related to the bridge unbalance, and duty-cycle is a function of the overall sensor bridge resistance, hence of the sensor operating temperature. In this way, two measurement values are simultaneously and independently carried on the same output signal. The circuit makes use of a constant current bridge excitation which enables the connection of remote sensors without accuracy degradation, and moreover, for silicon piezoresistive sensors, provides a first-order temperature compensation. A frequency-doubling output stage significantly reduces the nonlinearity due to switching delay times, at the parity of output center frequency and span. Experimental results are reported on the characterization of both the circuit alone and interfaced to a silicon pressure sensor
Original languageEnglish
Pages (from-to)585-590
Number of pages6
JournalIEEE Transactions on Instrumentation and Measurement
Volume49
Issue number3
DOIs
Publication statusPublished - 1 Jun 2000

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