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This paper presents a 1.5-GS/s 6-bit single-channel loop-unrolled successive approximation register (SAR) analog-to-digital converter (ADC) using speculative capacitive DAC (CDAC) switching control technique. The proposed SAR ADC achieves a high sampling rate by eliminating additional delays in typical loop-unrolled SAR ADCs related to settling time constraints in their CDACs. Specifically, the CDACs are duplicated and controlled in speculative ways so that the CDAC outputs passage to their next values before completing the regeneration operation of comparators, thereby improving timing constraints for successive approximations. The switching power overhead from the CDAC speculation is mitigated by introducing an energy-efficient CDAC control technique that produces desired voltage transients with minimal power overheads. The prototype of the proposed SAR ADC is fabricated in a 28-nm CMOS technology and occupies an active area of 0.0038-mm2. The design consumes 5.8 mW from a 1.2-V supply. The ADC achieves 1.5-GS/s sampling frequency with a 31-dB SNDR at a low input frequency and a 28.6 dB at the Nyquist frequency without applying any offset calibration techniques, achieving the highest sampling frequency among the 6-bit single-channel loop-unrolled SAR ADCs reported. [ABSTRACT FROM AUTHOR]

LAYout with Gridded Objects (LAYGO), a Python-based layout-generation engine for enhancing the design productivity of custom circuit layouts in advanced CMOS processes, is presented and verified by implementing a time-interleaved SAR (TI-SAR) ADC instance in a 16 nm CMOS FinFET technology. LAYGO supports rapid generation by placing customized templates on process-specific placement grids, thereby encapsulating the design rules and process-specific structures. The templates can be located based on their relative positional information, which further enhances the description capability and portability. Interconnecting wires are routed on the grids for design rule abstractions, with additional customizations and support for multi-patterning. The functions for the on-grid placement and routing use advanced indexing and slicing with multi-dimensional object containers to improve the description and parameterization capabilities. Multiple TI-SAR ADC layouts are generated using LAYGO in 28–16 nm CMOS technologies. One instance is fabricated in a 16 nm CMOS FinFET process and measured, achieving a 38.2 dB signal-to-noise-and-distortion ratio (SNDR) at 7 GS/s after digital calibration and consuming 45.2 mW. Owing to its high customization capability, the design achieved the highest sampling rate (7 GS/s) among the generated ADCs. [ABSTRACT FROM AUTHOR]