A digital self-calibration circuit for optical rotary encoder microsystems

This paper describes a digital self-calibration circuit for optical rotary encoders. The circuit performs dynamic calculation of the threshold level used by the waveform-shaping section of the read-out channel. This avoids the need for manual calibration, provides thermal stabilisation, and prevents performance degradation. The proposed digital calibration system was integrated in a conventional 0.8-/spl mu/m technology and was then experimentally evaluated.