PHASE MODULATION SIGNAL GENERATION CIRCUIT AND DISPLACEMENT DETECTION DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a phase modulation signal generation circuit (displacement detection device) in which the effect of a drift or arithmetic error arising from an analog multiplication process is avoided and circuit configuration is simplified.;SOLUTION: A phase modulation signal generation circuit 3 has: a modulation signal generation circuit 31 for generating a square wave modulation signal RsinT; a signal generation circuit 32 for shifting the phase of the modulation signal RsinT by 90° and generating gain control signals GSTL, GCTL; a series circuit of an analog switch 33 and a differential amplifier 34 for generating a balanced modulation signal Bc(T); a series circuit of an analog switch 35 and a differential amplifier 36 for generating a balanced modulation signal Bs(T); an addition circuit 37 for adding two balanced modulation signals Bc(T) and Bs(T), preferably, for current addition; and a low-pass filter (LPF) 38 having a small amount of attenuation.;SELECTED DRAWING: Figure 6;COPYRIGHT: (C)2016,JPO&INPIT