Noise parameters are commonly used to design low noise amplifiers (LNAs), which are generally the first stage of a radio frequency receiver. If the LNA feeds directly into a mixer, the noise parameters of the mixer can significantly raise the overall noise parameters of the system. The extraction of mixer- based system noise parameters is complicated by the frequency conversion enabled by the mixer where the noise power on the input is at a different frequency than that on the output. This paper describes the setup, noise receiver calibration and extraction of mixer noise parameters. Additionally, challenges in low-frequency noise receiver calibration are described and illustrated using measurement examples.

A revealing case study is presented to explore the impact of excess noise ratio (ENR) and vector network analyzer (VNA) mechanical coaxial calibration on accurate on-wafer noise parameter testing for ultra-low noise devices. On-wafer noise parameter tests were conducted on a GaAs pHEMT device from 2-50 GHz after calibration with three different noise sources. For each, ENR specified from an external calibration service and also with ENR measured internally using vector corrected noise power measurements with appropriate coaxial calibration kits. Initial results show that significant variation in noise parameters, especially Fmin can result from seemingly subtle differences in ENR values as well as coaxial calibration accuracy. Excellent agreement is demonstrated for noise parameter measurements made with the three different noise sources, after using in-house measured ENR values and eliminating the use of a suspect coaxial calibration kit.

Arbitrary-load-dependent X-parameters, automatically measured with a load-tuner working with an NVNA, are used to characterize and model a packaged 10W GaN transistor. A full nonlinear two-port functional block model for PA and other circuit design is immediately available for nonlinear simulation. It is demonstrated that the model predicts well the independent effects of harmonic load tuning without having to independently control harmonic loads during characterization. The nonlinear model can be used effectively to obtain optimal fundamental and harmonic impedances for device operation, as well as predict, accurately, other nonlinear FOMs including PAE and harmonic distortion. Source-pull is shown to be unnecessary except for efficient power transfer, yet the model is fully capable of predicting correct device response when embedded in any source and load impedance at the fundamental and harmonics.

Noise parameters are required to design, circuits to minimize the effect of noise, but noise parameters have traditionally been very slow and complex to measure. Now a new, ultra-fast method is shown, which is over two orders of magnitude faster, more accurate and simpler, requiring less operator skill to make the measurement.

X-parameters are the mathematically correct supersets of S-parameters valid for nonlinear (and linear) components under large-signal (and small-signal) conditions. This work presents an automated application combining a nonlinear vector network analyzer (NVNA) instrument with automated load-pull measurements that extends the measurement and extraction of X-parameters over the entire Smith Chart. The augmented X-parameter data include magnitude and phase as nonlinear functions of power, bias, and load, at each harmonic generated by the device and measured by the NVNA. The X-parameters can be immediately used in a nonlinear simulator for complex microwave circuit analysis and design. This capability extends the applicability of measurement-based X-parameters to highly mismatched environments, such as high-power and multi-stage amplifiers, and power transistors designed to work far from 50 ohms. It provides a powerful and general technology-independent alternative, with improved accuracy and speed, to traditional large-signal device models which are typically slow to develop and typically extrapolate large-signal operation from small-signal and DC measurements.

A new method for noise parameter measurements is introduced, with better than 100times speed improvement over traditional methods. The setup is simple and easy to configure, and the entire calibration and measurement process is very fast, making dense frequency spacing practical. The new method produces smoother data with lower scatter, and the dense frequency spacing eliminates shifts due to aliasing and makes it easier to identify the scatter and outliers.

These high-performance bad-pull tuners enable on-wafer measurements on power transistors at impedances of 1 Omega and less and at GSM RF power bevels to +35 dBm.