Integrated Time Domain Multiplexer for Superconducting Qubit Control at Millikelvin Temperatures

This paper presents a fully integrated time-domain multiplexer (MUX) circuit in IHPs SG13G2 BiCMOS technology that aims to interface multiple qubits of a superconducting (SC) quantum processor at millikelvin temperatures (mK). The design of the MUX is based on the characterization of different types of integrated NMOS transistors at temperatures below 100 mK. Insights into the temperature and W/L ratio dependent effects are presented and incorporated into the circuit design to achieve minimal static DC power consumption and optimal microwave performance at temperatures down to 45 mK. Using a series-shunt topology, the presented test structure achieves a static power consumption of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&lt;5 \text{nW}$</tex> and an on/off ratio of 20.2 dB at 5 GHz.