A CMOS phase to digital converter for optical encoders

In this paper, a CMOS phase to digital converter for optical encoders is newly proposed. This chip adopts a proposed phase-shift method to easily generate phase shifts of signals by using a resistor chain. Different to PLL-based and ADC-based interpolation, the complexity and hardware cost can be relaxed in this proposed chip. Based upon the device parameters of 0.5 μm 2P2M CMOS technology with 5 V power supply, all the functions and performance of the proposed CMOS phase to digital converter for optical encoders are successfully tested and proven through SPICE simulations. The physical layout of interpolation circuits and current to voltage converter are 1000 × 600 μm² and 850 × 760 μm², respectively. The proposed chip is suitable for optical encoders.