A cryogenic DAC operating down to 4.2 K

Abstract

This paper presents a 10 bit CMOS current steering digital to analog converter (DAC) that operates from room temperature to as low as 4.2K. It works as the core part of a cryogenic Silicon quantum computer controller circuit producing rapid control gate voltage pulses for quantum bits (qubits) initialization. An improved analog calibration method with a unique unit current cell design is included in the D/A converter structure to overcome the extended cryogenic nonlinear and mismatch effects. The DAC retains its 10 bit linear monotonic behavior over the wide temperature range and it drives a 50Ω load to 516mV with a full scale rise time of 10ns. The differential non-linearity (DNL) of the converter is 0.35LSB while its average power consumption is 32.18mW from a 3V power supply. The complete converter is fabricated using a commercial 0.5μm 1 poly 3 metal Silicon on Sapphire (SOS) CMOS process.