A 10.75-ENOB 20 MS/s SAR ADC for an UWB Transceiver Applied in Breast Cancer Detection in 180 nm CMOS

A 180 nm TSMC CMOS 11 bit asynchronous successive approximation register Analog-to-Digital converter (SAR ADC) is developed for a breast cancer detection ultra wide-band transceiver. To improve the linearity, a delay cell inside the asynchronous clock generator is implemented, allowing a larger settling time for the capacitor DAC. The implemented ADC occupies 0.1 mm ² , and post-layout simulation results show that it achieves an ENOB of 10.75 bit at a sampling rate of 20 MS/s without any calibration method. The power consumption is 2.89 mW at 1.8 V supply, thus achieving the figure of merits of Schreier (FoM _S ) and Walden (FoM _W ), 162 dB and 84 fJ/conversion-step, respectively.