A 4.6-373K Functional 800MS/s 12b Buffer-then-Amplify Charge-Pump-Based Pipelined TI-SAR ADC with Integrated-Active-Hold Technique

The growing demands of cryogenic quantum computing and wide-bandwidth aerospace/automotive wireless communications have created a demand for ADC technologies capable of operating across unprecedented temperature ranges, from room temperature down to 4K, while achieving higher sampling rates and resolution. While pipelined ADC architectures offer a promising solution, their residue amplifier designs face significant challenges in wide-temperature operation, whether implemented as multi-stage closed-loop amplifiers or open-loop amplifiers (Fig. 1). The fundamental challenge lies in the dramatic device parameter variations at cryogenic temperatures, where threshold voltage (Vt) shifts by approximately 100mV and carrier mobility increases by more than 1.5x [1]. These variations create distinct limitations for existing architectures. Multi-stage closed-loop amplifiers require complex bias calibration to maintain stability [2], while open-loop amplifiers [3]-[5] suffer from large gain variations [4], necessitating an unacceptable redundancy range. Open-loop amplifiers also suffer poor linearity, which mandates a high-resolution 1 st stage SAR quantizer and leads to longer conversion times [5].