An Open-Source 1.44-MS/s 703-μW 12-bit Non-Binary SAR-ADC Using 448-aF Capacitors in 130-nm CMOS

This paper presents the design of a self-clocked 12-bit non-binary fully differential SAR-ADC using the SKY130 open-source PDK. The entire mixed-signal circuit design and layout were created with free and open-source software. The ADC reaches a sample rate of up to 1. 44MS/s at 1. 8V supply while consuming 703 $\mu$W of power on a small 0.175m$\mathrm{m}^{2}$ area. A configurable decimation filter can increase the ADC resolution up to 16 bits while using an oversampling factor of 256. A 9-bit thermometer-coded and 3-bit binary-coded DAC matrix using a 448 aF waffle-capacitor results in a total capacitance of 1.83pF per input. Realizations of configurable analog functions using the form factor of SKY130 high-density standard cells allow the parametrization of an analog circuit in a hardware description language and hardening of the macro in an intentionally digital workflow.