Abstract: The analog-to-digital converter (ADC) serves as a bridge connecting the analog domain and the digital domain, holding significant importance for processing analog signals in the digital world. In recent years, the rapid development of quantum computing has presented opportunities for a range of cryogenic circuits. Among them, cryogenic ADCs operate within quantum readout circuits to read quantum states in real time. However, the cryogenic characteristics of CMOS devices, such as the emergence of the Kink effect, an increase in the threshold voltage, a rise in the subthreshold slope, and an increase in transistor mismatch, can affect the normal operation of ADC circuits, leading to performance degradation. This paper mainly reviews and summarizes existing cryogenic ADC circuits, systematically analyzes and provides an overview of their research and progress at low temperatures, examines the cryogenic characteristics of transistors and the design of comparators for cryogenic ADCs, and offers an out-look on future research directions for cryogenic ADCs.

Key words: analog-to-digital converter, quantum computing, cryogenic ADC, low-temperature characteristics, comparator