A Successive Approximate Angle Track Converter for Sinusoidal Encoders

Abstract

ABSTRACTThis paper presents a novel angle track converter for sinusoidal encoders. These encoders provide electronic signals in which the position is encoded in sinusoidal form. This work aims to reduce the complexity and enhance the conversion speed of the sinusoidal‐to‐angle demodulation system. Considering the periodicity of sine and cosine signals (SCSs), the full range is evenly divided into eight segments to determine the coarse angle. According to the specific coarse angle segment, the SCSs are reshaped for proceeding demodulation. Then a fine angle is derived from reshaped signals based on division and arctangent algorithm. Division operation is achieved by a capacitor digital‐to‐analog converter, dynamic comparator, and successive approximation register. The arctangent value is obtained from the division result with the compensation by a small‐size look‐up table. The new converter fabricated in 0.18‐m BCD technology occupies an active area of 0.16 mm2 and consumes 1.5 mW at the sample rate 10 MHz. The measured maximum error is 1.8°, in the full range. Without analog‐to‐digital converters and no nonlinear operation unit, the proposed angle track converter has a significant advantage in cost, speed, and efficiency.