Design of a 12 bit SAR ADC with Self-Calibration

Abstract

Successive approximation analog-to-digital converter (SAR-ADC) are widely used in intelligent sensing fields due to it’s low power consumption, medium and high precision and such characteristics. Traditional binary SAR ADC have non-ideal factors such as DAC capacitor array mismatch and comparator offset, which severely limit it’s performance. Therefore, a self-calibration method for non-ideal factors is proposed in this work, and theoretical derivation and simulation analysis are carried out. A 12-bit non-binary SAR ADC with self-calibration is designed based on the TSMC 40nm CMOS process, which reduces the capacitance area, improves the conversion accuracy, and eliminates most of the errors caused by non-ideal factors. Simulation results show that the ADC’s SNDR is 72.01dB, and INL within +1.2/-1LSB, meets most of the market requirements.