A Cryogenic Integrated Noise Calibration and Coupler Module Using a MMIC LNA

TL;DR

This paper introduces a low-power cryogenic noise calibration module integrated with a MMIC LNA, improving calibration accuracy for radio astronomy receivers by reducing frequency structure and enhancing stability.

Contribution

It presents a novel cryogenic noise calibration source with minimal power dissipation, suitable for integration into cold receiver components, and demonstrates its effectiveness in a real telescope system.

Findings

Lower noise power output variability across frequency

Enhanced long-term stability of calibration source

Successful deployment on NRAO GBT receiver

Abstract

A new cryogenic noise calibration source for radio astronomy receivers is presented. Dissipated power is only 4.2 mW, allowing it to be integrated with the cold part of the receiver. Measured long-term stability, sensitivity to bias voltages, and noise power output versus frequency are presented. The measured noise output versus frequency is compared to a warm noise diode injected into cryogenic K-band receiver and shows the integrated noise module to have less frequency structure, which will result in more accurate astronomical flux calibrations. It is currently in operation on the new 7-element K-band focal plane array receiver on the NRAO Robert C. Byrd Green Bank Telescope (GBT).