Modeling and Analysis of Digital-to-Analog Converter Non-Idealities in Microwave Kinetic Inductance Detectors Readout

The Microwave Kinetic Inductance Detector (MKID) is a millimeter-wave-length light detector made with a radiofrequency superconductor resonator that exhibits the characteristic of high resonance quality factor (Q), enabling the multiplexing of hundreds of MKIDs on a single signal transmission line. In this study, we investigate the Digital-to-Analog Converter (DAC) of the current readout solution. Specifically, we developed a functional model of the DAC, including its slew rate and saturation limitations, and demonstrated its validity by comparing it with measurement results. This model allows to analyze the influence of the DAC's limitations across the entire frequency spectrum, and to examine its impact on the maximum frequency multiplexing factor. We demonstrate that the non-idealities of the DAC limit the maximum frequency multiplexing factor, which depends on the number of sinusoids, their amplitude, and phase.