Instrumentation of a high-sensitivity microwave vector detection system for low-temperature applications

TL;DR

This paper details a high-sensitivity microwave vector detection system designed for low-temperature studies of low-dimensional electron systems, achieving superior resolution in amplitude and phase measurements at very low power levels.

Contribution

The paper introduces a novel detection system with phase-locked loop and double-pulse modulation, enhancing measurement resolution for low-temperature electron systems.

Findings

Achieves better amplitude and phase resolution than conventional analyzers.

Operates effectively at power levels below -65 dBm.

Enables precise phase change detection in low-dimensional electron systems.

Abstract

We present the design and the circuit details of a high-sensitivity microwave vector detection system, which is aiming for studying the low-dimensional electron system embedded in the slots of a coplanar waveguide at low temperatures. The coplanar waveguide sample is placed inside a phase-locked loop; the phase change of the sample may cause a corresponding change in the operation frequency, which can be measured precisely. We also employ a double-pulse modulation on the microwave signals, which comprises a fast pulse modulation for gated averaging and a slow pulse modulation for lock-in detection. In measurements on real samples at low temperatures, this system provides much better resolutions in both amplitude and phase than most of the conventional vector analyzers at power levels below -65 dBm.