A CMOS-Readout-Amplifier For Instrumentation Applications

In the recent years enormous progress has been made in integration of sensors and electronics on the same silicon substrate. So a strong demand for incorporated instrumentation amplifiers has arisen. In this paper we present a fully integrated CMOS version of such an amplifier using switched capacitor techniques. The amplifier system provides differential input capability, programmable amplification, clock generation, and low-pass filtering on the chip. The output signal is continuous in time and the system can be used without any special precautions necessary for sampled-data circuits. Emphasis was laid on high PSRR, low noise and offset, low harmonic distortion, and small amplification error. For covering a large field of applications only slightly different realizations can be used for capacitive sensors as well as for resistive sensor bridges.