A circuit-design-driven tool with a hybrid automation approach for SAR ADCs in IoT

Ming Ding, Guibin Chen, Pieter Harpe, Benjamin Busze, Yao-Hong Liu, Christian Bachmann, Kathleen Philips, Arthur H. M. van Roermund

Abstract: A circuit-design-driven tool with a hybrid design automation approach for asynchronous SAR ADCs in IoT applications is presented. To minimize the circuit design time while still being able to maintain ADC performance, the hybrid approach allocates automation and manual effort properly for each block: fully-synthesized control logic, highly-automated DAC and S&H circuit, library-based comparator and template-based layout generation. A user interface governs the automated design flow from specification and circuit implementation to layout generation. Two prototypes are generated using the proposed flow in 40nm CMOS: an 8b 32MS/s and a 12b 1MS/s SAR ADC. The measured and the simulated ADC performance are in good agreement, showing the robustness of the proposed method. At 1V supply, two chips consume 187μW and 16.7μW, achieving 30.7fJ/conversion.step and 18.1fJ/conversion.step respectively.