On-Line Monitoring and Error Correction in Sensor Interface Circuits Using Digital Calibration Techniques

The functionality of modern integrated circuits is affected by numerous non-ideal effects. Especially during the design of analog circuit components, much effort is invested in compensating these effects by various methods. In this work, an alternative approach is presented, which is based on digital calibration techniques and used in a sensor interface circuit. A suitable test signal is interleaved with the sensor signal, whereby the interface is permanently monitored. Static and dynamic errors are detected in this way without interrupting normal sensor activities. Afterwards, these errors are determined and corrected in the digital domain by adaptive filters. Hereby, an on-line error correction is realized, which allows the sensor interface to react to changing ambient conditions and makes it more robust. Furthermore, the design requirements of the analog circuit components can be drastically reduced since not all errors need to be fully compensated in the analog domain. The introduced approach is demonstrated by correcting different gain- and offset-errors in a 65 nm CMOS sensor interface.