Auto-gain method for stabilizing sinusoidal signals of optical encoders

Abstract

Optical encoders are widely used in precision positioning, yet signal amplitude attenuation due to grating tilt degrades phase resolution and linearity. In this manuscript, we analysed the amplitude-related resolution and proposed an auto-gain method based on programmed gain control and the CORDIC algorithm to stabilize sinusoidal signals. Experimental results demonstrate that the method amplifies signal amplitudes by approximately 11 times and reduces displacement nonlinearity by 69 %, significantly enhancing measurement resolution and stability. The approach is implemented on an FPGA-based phasemeter platform using programmable gain amplifiers and digital potentiometers, offering effective signal conditioning for optical encoders under varying operational conditions.