White Paper: Cryogenic Modelling
of GaN for Monolithic Microwave
Integrated Circuits (MMIC)
Executive Summary
This white paper explores the development of intellectual property (IP) libraries for Gallium Nitride (GaN) operating in cryogenic environments. The goal is to foster the creation of high-efficiency, high-frequency, and microwave
components, primarily for use in Monolithic Microwave
Integrated Circuits (MMIC). By tapping into GaN’s
superior voltage, rapid switching speeds, and wide
temperature operation capabilities, we aim to provide an open-source IP library for widespread commercial and
custom applications, addressing power efficiency
challenges in the emerging field of quantum computing among others.
1. Introduction
GaN, compared to traditional Complementary
Metal-Oxide-Semiconductor (CMOS) and other III-V
materials like GaAs and InGaP, offers superior
high-voltage, fast-switching, and high-temperature
operation. GaN’s 30% improved electron mobility translates to significantly high power efficiency, making it an optimal solution for high-voltage, fast power switching applications at microwave frequencies in cryogenic environments. The resulting energy efficiency limits the thermal load required for operation, offering distinct advantages for applications such as current switching, RF switching, and low noise RF delivery systems.
2. GaN Cryogenic IP Library Development
We propose the development of IP libraries and piece parts optimized for operation across various cryogenic
environments (4K to 77K). The resulting open-source IP
library will be readily available to the UK community and beyond, for use in commercial off-the-shelf (COTS)
products and custom Application Specific Integrated
Circuits (ASICs). Key to this proposal is the integration of this capability into broader silicon solutions already
established, a task mostly solved by industry leaders
including Intel, TSMC, Global Foundries (GF), and Amkor.
The developed cryogenic IP library will be targeted
towards major GaN foundries (Wolfspeed, Qorvo, INEX, etc.) to create an open-source library accessible to any ASIC or MMIC design house. The intent is to develop a set of fundamental standard cell libraries needed to construct more complex application-specific specialty applications.
The initial focus of the library will include IP families
that cover:
Low Power FETs
High Power FETs
Controller FETs
Current Sources
Current Switches
Voltage Switches
Amplifiers
3. Addressing Quantum Computing Power Efficiency
The scalability of quantum computing approaches is
contingent on addressing power efficiency. Current
estimates indicate power per qubit to be around 6.25W/qubit, resulting in substantial power requirements and
operating costs. To make quantum computing
operationally affordable, a strong focus on architecture, design, and materials selection is crucial. The integration of classical electronics subsystems is vital to reduce
losses in power delivery to the quantum trap chips. To maximize the impact, we aim to transition to more
energy-efficient materials like GaN with area-efficient footprints for dramatic power reductions.
4. Broadening the Scope of Application
The proposed library development could also serve
a wider community. Traditional IP libraries cover
commercial, automotive, or military temperature ranges, but cryogenic applications operating between -273C to -195C require custom library characterization and
development. GaN’s low-temperature operation,
smaller footprints, and high power efficiency are beneficial for multiple applications outside of quantum computing,
including the space sector and high sensitivity
detection systems.
5. Conclusion
The modelling and development of cryogenic GaN
components for MMIC promise a series of breakthroughs in power efficiency, particularly relevant for quantum
computing and other high-demand applications. By
creating an open-source IP library and encouraging the
integration of GaN into a wider range of products, the
project opens a path towards affordable, scalable, and
efficient technology solutions.
