Accurate digital interface with low-component count for sine-cosine shaft encoders
A digital high-accuracy interface for sine–cosine shaft encoders (SCE) is proffered. The outputs of SCE vary as a sine and cosine functions of shaft angle. The proposed interface processes these outputs and renders a linear direct-digital output for 360° operating range. The interface has minimal dependence on many circuit non-idealities including the phase error of quadrature oscillator. The performance of the interface is verified using simulation and emulation-based studies. Furthermore, the interface is tested with a magneto-resistance-based SCE. Test results show that the output non-linearity remains around 0.27% for typical values of phase errors. The interface also possesses features such as low-component count, high linearity, direct-digital output etc.
