Characterization of Zero-Bias Microwave Diode Power Detectors at Cryogenic Temperature

TL;DR

This study characterizes commercial tunnel diode microwave power detectors at both room and cryogenic temperatures, revealing temperature-dependent sensitivity, noise floors, and flicker noise characteristics at 10 GHz.

Contribution

It provides detailed measurements of tunnel diode performance at cryogenic temperatures, highlighting their potential for low-noise microwave detection in cryogenic environments.

Findings

Differential gain increases from 1,000 V/W to 4,500 V/W at 4 K as power increases.

White noise floor NEP of 0.8 pW/√Hz at 4 K and 8 pW/√Hz at 300 K.

Flicker noise spectral density is -120 dB/Hz at 4 K, 10 dB higher at room temperature.

Abstract

We present the characterization of commercial tunnel diode low-level microwave power detectors at room and cryogenic temperatures. The sensitivity as well as the output voltage noise of the tunnel diodes are measured as functions of the applied microwave power, the signal frequency being 10 GHz. We highlight strong variations of the diode characteristics when the applied microwave power is higher than few microwatt. For a diode operating at ${4}$ K, the differential gain increases from ${1,000}$ V/W to about ${4,500}$ V/W when the power passes from ${-30}$ dBm to ${-20}$ dBm. The diode present a white noise floor equivalent to a NEP of ${0.8}$ pW/ ${\sqrt{\mathrm{Hz}}}$ and ${8}$ pW/${ \sqrt{\mathrm{Hz}}}$ at 4 K and 300 K respectively. Its flicker noise is equivalent to a relative amplitude noise power spectral density ${S_{\alpha}(1~\mathrm{Hz})=-120}$~dB/Hz at ${4}$ K. Flicker noise is 10 dB higher at room temperature.