Measuring Noise Parameters Using an Open, Short, Load, and 1/8-wavelength Cable as Source Impedances

TL;DR

This paper introduces a novel noise parameter extraction method using open, short, load, and a cable as source impedances, enabling measurements with high-reflection sources and suitable for low-frequency applications.

Contribution

It presents a singularity-free matrix approach for noise parameter extraction using OSLC sources, improving measurement feasibility at frequencies below 1 GHz.

Findings

OSLC method effectively extracts noise parameters with high-reflection sources.

The approach simplifies low-frequency noise measurements for low-noise amplifiers.

It avoids matrix singularities present in traditional methods.

Abstract

Noise parameters are a set of four measurable quantities which determine the noise performance of a radio-frequency device under test. The noise parameters of a 2-port device can be extracted by connecting a set of 4 or more source impedances at the device's input, measuring the noise power of the device with each source connected, and then solving a matrix equation. However, sources with high reflection coefficients cannot be used due to a singularity that arises in entries of the matrix. Here, we detail a new method of noise parameter extraction using a singularity-free matrix that is compatible with high-reflection sources. We show that open, short, load and an open cable ("OSLC") can be used to extract noise parameters, and we detail a practical measurement approach. The OSLC approach is particularly well-suited for low-noise amplifier measurement at frequencies below 1 GHz, where alternative methods require physically large apparatus.