A 14-bit 5MS/s SAR ADC with digital calibration algorithm for OLED display touch system

In this article, we propose a 14-bit successive approximation register (SAR) analog-to-digital converter (ADC) based on digital calibration algorithm for large-size organic light-emitting diode (OLED) display touch chip. The SAR ADC uses a digital-to-analog convertor (DAC) segmented into two sub-DACs in each channel. A total of two channels are used in the ADC to realize interleaved sampling. The proposed digital calibration technique improves the spurious free dynamic range (SFDR) over 30 dB and reduces the integrated non-linearity (INL) over ten times with different capacitive DAC mismatches. The peaks of differential non-linearity (DNL) and INL are measured to be 0.520 LSB and 1.027 LSB, respectively. The 14 bit 5 MS/s ADC achieves an ENOB of 12.4, a power consumption of 1.054 mW by 110-nm CMOS process, and leads to a figure of merit (FoM) of 14.08 fJ/conv.-step.