Multi-Channel Differential Synchronous Demodulator for Linear Inductive Position Sensor

Abstract

A multi-channel differential synchronous demodulator is proposed for third harmonics suppression in three-phase receiving coils based linear inductive position sensor, which is realized by taking envelope differences of every two induced signals on three-phase receiving coils as differential signals. The proposed demodulator includes a differential synchronous envelope detector (DSED), and a time division MUX (TDM). By using the DSED, the envelope differences are synchronously demodulated as differential signals. The TDM including a multi-channel selector, a MUX and a voltage follower, is used for independently outputting the corresponding differential signals for linear position calculation. The proposed demodulator was designed in a 180 nm CMOS process and verified by Spectre simulator. Simulation results show third harmonics of differential signals are improved by 17.4 dB, indicating the proposed demodulator could be a candidate for designing the high performance analog front-end of inductive position sensor.