A 13.44-Bit Low-Power SAR ADC for Brain-Computer Interface Applications

This paper presents a successive approximation register analog-to-digital converter (SAR ADC) specifically optimized for brain-computer interface (BCI) applications. Designed and post-layout-simulated using 180 nm CMOS technology, the proposed SAR ADC achieves a 13.44-bit effective number of bits (ENOB) and 27.9 mu W of power consumption at a supply voltage of 1.8 V, enabled by a piecewise monotonic switching scheme and dynamic logic architecture. The ADC supports a high input range of +/- 500 mV, making it suitable for neural signal acquisition. Through an optimized capacitive digital-to-analog converter (CDAC) array and a high-speed dynamic comparator, the ADC demonstrates a signal-to-noise-and-distortion ratio (SINAD) of 81.94 dB and a spurious-free dynamic range (SFDR) of 91.69 dBc at a sampling rate of 320 kS/s. Experimental results validate the design's superior performance in terms of low-power operation, high resolution, and moderate sampling rate, positioning it as a competitive solution for high-density integration and precision neural signal processing in next-generation BCI systems.