A Method of Sinusoidal Phase Signal Correction Using Summing and Subtraction Topology for Improving Encoders Performance

Encoders are angular and speed position sensors that are mainly used in a motor feedback system. There are several types of technology to design an encoder sensor ranging from optical system, magnetic system, capacitive system and inductive system. The choice of technology and the specifications of the encoder system will depend on the application usage. Some application requires an encoder to be small in size, low cost and only need to have the most basic of functions. In practice, the very basic of an encoder output needs to contain two signals which are 90 degrees apart. These signals generated from the sensors are crucial for the accuracy of the encoder but in reality these are not ideal. They will contain different amplitudes, phase shifts, dc offsets and noise due to the mechanical & electrical construction. This paper will present a method of improving phase shifts between the sinusoidal signals done in a simple analog blocks configuration that does not need digital processing which is suitable to be used in a small size and low cost encoders. The method will be modelled and simulated first in MATLAB and then implement into the analog blocks using TSMC 0.25um process. Results of the simulation from the analog implementation will be presented to show the improvement in the phase errors