An analog signal processing circuit for linearity compensation to extend the measuring range of eddy current displacement sensor for stop lamp switch

Abstract

This paper presents an analog signal processing circuit for linearity compensation to extend the measur-ing range of the eddy current displacement sensor (ECDS) for stop lamp switches (SLS). An ECDS can be a con-tactless type switch that ensures semi-permanent operation, and is proposed as a new structure for SLS. A new displacement-dependent quality factor model for the primary transducer (PT) of an ECDS is proposed. This model describes the non-linear behavior of the PT. An analog signal processing algorithm that linearizes the pro-posed model is suggested and implemented in a high voltage 0.35um CMOS technology. By the adoption of the implemented chip, the measuring range of an ECDS is extended by two times compare to that of the conven-tional ECDS.