A frontend for direct RF-synthesis on the basis of a ZCU216 board

by Valentin Stümpert (KIT)

Thursday Feb 16, 2023, 2:00 PM → 3:00 PM Europe/Berlin

https://kit-lecture.zoom.us/j/63359551762?pwd=SEFxS2hCZGUyU2FzOE1IbXhtWm9XUT09 (R413 & Zoom)

Lecture to the master thesis from Valentin Stümpert on the Topic: A frontend for direct RF-synthesis on the basis of a ZCU216 board

Current quantum computing research using superconducting qubits creates the need for highly flexible RF signal generation and data acquistion platforms. Similar requirements are shared by other cryogenic sensor technologies leveraging SQUID interfacing. In this work, an RF frontend for the control and readout of cryogenic circuits via an SDR system is developed. It iterates on existing solutions in use for superconducting multi-qubit systems. Established mixer based circuitry is to be superseeded by leveraging hardware advances in direct RF sampling integrated in SoCs. Software configuration of signal paths, without the need for physical rewiring, is retained and extended from signal transmission to reception channels. Capabilities for DC-coupled flux pulse signals are implemented.

The work will present an introduction to superconducting circuits, their microwave interfacing and established FPGA based SDR system for readout and control. An overview of related cryogenic sensors will also be given. Furthermore, requirements for more versatile signal processing hardware, with higher channel counts and increased fidelity, are analysed. The design process focusing on schematic capture and PCB layout for modular and repeatable design is presented. Mechanical integration of the frontend for upcoming in-system use was considered and assembly, as well as first bring up of the prototype, was successfully performed. Finally, the implementation is validated against the specification and compared to previous works. Insufficiencies and the alleviations of layout peculiarities (vias, voids, component choice) are adressed both in situ and for revisions. A conclusion is drawn to determine viability and success of implementation.