High-Accuracy Millimeter-Wave Noise Figure and Noise Parameter Measurements

Accurate noise figure and noise parameter

measurements on mm-wave transistors

Noise figure is the most commonly used measure of device-added noise. It is usually measured in a 50-Ω environment and seeks to quantify the signal-to-noise degradation caused by an amplifier or frequency converter. Noise figure, however, varies with the source impedance presented to the amplifier, so is not sufficient to fully characterize your devices 

The variations due to source impedance can be characterized and represented in terms of noise parameters. It is essential to understand the noise parameters of your devices, especially when designing low-noise amplifiers using mismatched transistors. 

Noise parameters are comprised of four distinct elements: Fmin, the minimum noise figure of the transistor, Gopt, the optimum impedance at which Fmin occurs (in real and imaginary terms), and Rn, the equivalent series resistance of the transistor. In theory, any four controlled impedances (GS) can be presented to the device and the corresponding noise figures (F) measured in order to solve four simultaneous equations for four unknowns. Practically, the impedances selected for GS should be in the range of Gopt and proper impedance selection becomes critical if the transistor is non-50-Ω.

• Millimeter-wave noise figure and noise parameter measurements
• Based on Keysight PNA-X Series network analyzer
• Maury automated impedance tuner for non-50-Ω device measurements
• Maury external noise receiver module increases sensitivity by up to 6 dB
• Maury test software for automated control of measurements
• Tests wideband noise parameters between 8 and 50 GHz
• Improves accuracy and speed of noise measurements
• High accuracy measurements on millimeter-wave transistors

High-Accuracy Millimeter-Wave Noise Measurements

that controls an electronic impedance tuner. For the N5241/42B, an external ECal is used, and for the N5244/45/47B, a built-in electronic tuner is included. The embedded tuner can be used to present the impedances required to solve the unknowns in the noise-parameter equation, but is best suited for 50-Ω or near-50-Ω devices. For non-50-Ω applications, the PNA-X can be used with Maury Microwave’s MT984AL01 or MT985AL01 external automated impedance tuner in order to present impedances closer to Gopt. The Keysight PNA-X is also the only instrument to combine S-parameter receivers with a dedicated and optimized low-noise receiver. The sensitivity of the noise receiver is critical in measuring noise figure by accurately measuring the noise-power contribution of the device-under-test. The accuracy of the noise measurement is directly related to the second-stage noise figure of the noise receiver, and the lower the better. The sensitivity of the PNA-X noise receiver is sufficient for many applications and, if necessary, can be increased with the use of an external noise receiver module. The addition of a Maury Microwave MT7553B03 external noise-receiver module allows the second-stage noise figure to be reduced by 5 to 6 dB. The combination of the Keysight PNA-X network analyzer, the MT984AL01 or MT985AL01 automated impedance tuner, the MT7553B03 noise-receiver module, and Maury’s MT993-series ATS software suite allows wideband noise parameters to be measured between 8 and 50 GHz with improved speed and accuracy. Keysight’s PNA-X combined with Maury’s tuner, receiver, and test software allows you to achieve high-accuracy noise figure and noise parameter measurements on your millimeter-wave transistors.