30 GHz-voltage controlled oscillator operating at 4 K

TL;DR

This paper demonstrates a 30 GHz voltage controlled oscillator operating at 4 K, maintaining functionality and stable frequency, suitable for integration with quantum computing systems at cryogenic temperatures.

Contribution

First low-temperature measurements of a 130 nm BiCMOS SiGe VCO, showing stable operation and detailed characterization from room temperature to 4 K.

Findings

Device maintains functionality from 300 K to 4 K

Frequency shifts 3% with temperature, 0.02% with magnetic field

Output power tends to increase at low temperatures

Abstract

Solid-state qubit manipulation and read-out fidelities are reaching fault-tolerance, but quantum error correction requires millions of physical qubits and thus a scalable quantum computer architecture. To solve signal-line bandwidth and fan-out problems, microwave sources required for qubit manipulation might be embedded close to the qubit chip, typically operating at temperatures below 4 K. Here, we perform the first low temperature measurements of a 130 nm BiCMOS based SiGe voltage controlled oscillator. The device maintains its functionality from 300 K to 4 K. We determined the dependence of frequency and output power on temperature and magnetic field up to 5 T and measured the temperature influence on noise performance. While the output power tends to increase, the frequency shift is 3 % for temperature and 0.02 % for the field dependence, respectively, both relevant for highly coherent spin qubit applications. We observe no improvement on output noise, but increased output flickering.