Noise parameter measurement systems from Focus-Microwaves

The four noise parameters used to describe low-noise preamplifiers are determined by measurement using a mechanical tuner at the input of the preamplifier. The measurement method used is mainly the cold method, which requires the measurement of the S-parameters of the preamplifier. To measure these precisely, an input switch module and a noise receiver module are required. Together with our partner Focus-Microwaves, we offer all necessary instruments as well as a comfortable SW suite for coaxial and waveguide noise measurement systems. Coaxial systems are available up to 67GHz, waveguide systems up to 170GHz.

Noise parameters (example)	Cycles of constant noise figure in Smith chart for input reflection coefficient.
Yopt = Gopt + jBopt Gopt = 0,00414 Siemens Bopt = -0,0103 Siemens Fmin = 1,0 dB Rn = 40 W Yopt from this example corresponds to an input reflection coefficient of: Re{Gamma_opt} = 0.4 Im{Gamma_opt} = 0.6

Circles for constant Noise Figure in the Smith Chart

Coaxial measuring systems

The required instruments and components are designed with coaxial connection. The specimen can either be coaxial or contacted as a chip on a wafer prober with probes. Especially elegant is the use of Keysight’s PNA-X network analyzers for S-parameter measurement and noise level measurement with built-in noise receiver. For higher frequency ranges, e.g. from 40-67GHz, which some noise receivers do not support, receiver modules with down converters are offered.

The input switch module is used to select whether the noise source or a port of the network analyzer is switched to the input of the tuner.

The receiver modules contain a low-noise broadband preamplifier to raise the noise signal of the sample amplifier to a well detectable noise power. At least the conversion loss of the down-converter and the cable loss should be exceeded to achieve good measurement accuracy.

The modules are controlled by a controller module, which establishes the communication to the measurement recording SW and switches the modules to the correct state. A fundamental tuner is used as tuner. The DELTA tuners for use on the wafer prober achieve a particularly high VSWR for the source impedance, since no connecting cable is required.

Modules and Tuner for Noise Parameter Testing

Waveguide measurement systems

Waveguide measurement systems for noise parameters are used when low losses have to be achieved or very high frequencies have to be reached. If no network analyzer is available which can cover the measurement frequency range directly, frequency range extension modules are needed. For this purpose we recommend the very reliable modules from Virginia Diodes.

With Focus-Microwaves we offer modules in which the receiver circuit is combined in one package. A waveguide switch is used at the input.

FDCS SW-Modul Noise Measurements NPEx

The proven SW Design Suite FDCS is extended for this purpose with the module NPEx for noise parameter measurements. The following functions are supported:

• Calibration of the measurement system with graphical menu navigation
• Measurements with “Cold” or “Hot/Cold” measurement principle
• S-parameters and noise measurements for various DC operating points and frequencies
• Extraction and graphical display of measurement data
• De-embedding of noise parameters to the reference level of the DUT (device under test)
• Display of stability circles and available gain
• Automation of noise measurements with FDCS SW module “NP Macro”

With the graphical visualization tool “Data Explorer”, measurement data and extracted noise parameters can be displayed in a variety of ways in the process.