A Single-Chip Smart Pressure Sensor Family with 2 Dimensional Calibration

Abstract

We present a single-chip CMOS solution for a pressure transducer reaching an 1% accuracy over the temperature range between -40°C and 125°C after calibration that delivers a ratiometric analog output voltage and a pulse density digital output. Two on-chip sensors are cointegrated: a surface-micromachined capacitive pressure sensor and temperature sensor using parasitic bipolar transistors. The surface-micromachined capacitive pressure sensor is fully compatible to a standard CMOS-process and therefore cost-optimized when compared to piezoresistive sensor elements. The sensor signal processing covers the sensor readout, the linearization, and the temperature sensor based compensation of the temperature sensitivity. A highly efficient parallel and automated calibration based on ∑△-modulators requires only a few calibration points for full pressure and temperature range. The two-dimensional calibration procedure has been optimised for parallel processing and allows efficient mass production. The sensor chip family has been fabricated in an 1.2 μm CMOS-process with surface micromachining extension and occupies a chip area of 11.8 mm.² The power consumption of the sensor chip is 6 mW using a 5 V power supply.