A 95 dB SFDR, 30mWDigital Interface Circuit for a TMR Sensor

摘要

A high-precision digital interface circuit is achieved for a tunnel magneto-resistance sensor with a high sensitivity and highdynamic range. The analog front-end detection circuit adopts the structure of a current feedback instrumentation amplifier,and a chopper technology and ripple suppression loop are used to improve the performance. In the back-end digital conversionpart, a fourth-order fully feedforward sigma-delta modulator is designed, and the chopper circuit is further applied to eliminatethe low frequency noise and offset of the first-stage integrator. The measurement results show that with the input equivalentmagnetic field signal amplitude of 100 mV centered at 31 Hz, the SFDR of the final digital output stream reaches 95 dB, andthe overall power consumption is 30 mW.