Low-Offset CMOS Analog Amplitude Calculation Circuit in Hall Angle Sensor

Abstract

Considering the hall angle sensor applications, a novel amplitude calculation circuit for sine and cosine signals is presented. It is consisted by double sampling and holding circuit, squaring circuit and summing circuit. By utilizing same MOSFETs rather than the traditional current mirror structure in the double sampling and holding circuit, the influence of the input offset voltage of the amplifier is eliminated. The proposed squaring and summing circuits eliminate the angular information to obtain the square of the amplitude of the sine and cosine signals. Spectre simulation results show that the squaring circuit works well in a 0.18 um CMOS process with 1.2 % output linearity error. The Monte Carlo simulation shows that the standard deviation of output is only 3.19 mV.