Cryogenic CMOS RF AWGs for Qubit Control

This article presents design approaches for two radio frequency (RF) arbitrary waveform generators (AWGs) operating at cryogenic temperatures using FinFET CMOS technologies. This article presents power, performance, and area tradeoffs for highly scaled quantum computing systems using different types of qubits (spin and transmons). The first considered design uses a direct digital synthesis (DDS) approach to provide a wide bandwidth (1-18 GHz) control solution for spin qubits. As this design point was implemented in two technology nodes (14- and 7-nm CMOS), it offers a window into the benefits for this application arising from technology scaling. Furthermore, the DDS architecture offers flexibility to meet the requirements of the rapidly evolving requirements of spin qubits and naturally supports a high degree of programmability of the amplitude, phase, duration, frequency, and spacing of control waveforms. The DDS-based wideband RF digital-to-analog converter (DAC) was demonstrated to be operational over the full 1–18-GHz target operating range, providing sufficient bandwidth for control signals for state-of-the-art spin-qubit platforms. The second design approach uses various techniques for highly reconfigurable, low-power control waveform generation for transmon qubits using current-mode analog design. This second approach, implemented using two 14-nm FinFET CMOS designs, has enabled the investigation of design-driven power scaling techniques. The DDS-based single spin-qubit controller consumes 40-140 mW, occupying 0.5 mm² in a 14-nm FinFET node implementation, and 30-68 mW, occupying 0.1 mm² in a 7-nm FinFET node. The current-mode transmon qubit controller designs, both implemented in 14-nm FinFET, consume 23 and 12.8 mW, respectively, occupying 1.61 and 1.32 mm² per qubit controller, respectively.