Interface circuit design and implementation for MEMS pressure sensor in tire pressure monitoring system

This paper presents an interface circuit for MEMS pressure sensor in tire pressure monitoring system. For the application of handling different output zeropoints of different sensors and adjusting the output common mode voltage for flexible use, a dedicated 3-Opamp instrument amplifier(In-Amp) and a cyclic ADC is adopted. The In-Amp is fabricated in a 0.35μm automotive electronic 2P4M BCD process. With a gain of 60, the test results show that the DC CMRR is 77.5dB and the input noise voltage at 1KHz is 96.8nV/√Hz. The cyclic ADC has an 8 bit resolution and the sample rate is set as 4KHz. The post-simulation result shows that the SFDR is 71.8dBc and SNDR is 49.4dB. The ENOB is calculated as 7.9 bit. The whole sensor interface circuit and an In-Amp with EMI design have been taped out in the 0.35μm automotive electronic 2P4M BCD process.