Self-calibration of neural recording sensors

This paper reports a calibration system for automatically adjusting the bandpass and gain characteristics of programmable E×G sensors. The calibration mechanism of the bandpass characteristic is based on a mixed-signal tuning loop which uses as feedback signal the output of the data converter following the signal conditioning of the E×G sensor. Intended high-pass and low-pass frequency poles of the transfer function are injected into the loop by means of a direct frequency synthesizer followed by a smoothing atenuator.