Programmable CMOS Interface for Resistive Bridges

A.J. Lopez-Martin and A. Carlosena (Spain)


CMOS Analog Integrated Circuits, Sensor Interfaces


A single-chip CMOS interface circuit optimized for resistive bridge sensors is introduced. Emphasis is placed on low cost, minimizing silicon area and number of external components. It provides a 2-bit programmable current source for sensor biasing, a 4-bit programmable gain instrumentation amplifier, two 10-bit Digital-to Analog converters and an internal EPROM for storing the calibration data and configuring the interface. The signal processing tasks performed include 10-bit Analog-to Digital Conversion, averaging, and compensation of offset, offset temperature coefficient, full-span output, full-span output temperature coefficient, as well as correction of sinusoidal nonlinearity. Measurement results of the fabricated circuit are in excellent agreement with the expected performance.

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