A Novel Sinusoidal Encoder-to-Digital Converter Based on Integrated Phase Shift and Interpolation Technique

Sinusoidal encoders are used to measure angular or linear displacement. These encoders provide electrical signals depending on the sine/cosine function of the position $\theta $ . A suitable converter is necessary to derive $\theta $ from sine/cosine signals (SCSs). This article proposes a novel demodulation method with low cost, low power consumption, and high accuracy. The proposed strategy converts the SCSs into a pseudolinear constructor using analog phase shift technology at first. Nonlinearity quantization of the pseudolinear constructor determines coarse phase $\theta _{C}$ indirectly. Then, a fine measurement $\theta _{F}$ is derived from the residual signals by the analog interpolation technology. These two parts are added to yield a precise position measurement $\theta _{\mathrm { es}}$ . The theoretical maximum error of the proposed algorithm is only $2.88\times $ 10 $^{-7} {}^{\circ }$ over a full range. The proposed converter has been fabricated in the 0.18- $\mu $ m CMOS technology with an active silicon area of 0.5 mm2. The experimental results prove the converter feasibility with 0.33° accuracy with a five-pole inductive angle sensor, occupying 3.3-mW power consumption. This article describes all the details of the theory, simulation, and experimental results.