Systematic Errors of Noise Parameter Determination Caused by Imperfect Source Impedance Measurement

Rectangular-waveguide vector-network-analyzer calibrations with imperfect test ports

“…As there is no transmission between the two ports through T SHORT , some care must be taken to formulate the problem to avoid singularities. An elegant solution based on forming wave vectors based on the reflection coefficients is provided in [4]. Alternatively, Appendix I provides formulas for directly cascading the scattering parameters without the use of transmission parameters.…”

Suppression of low-frequency interferences in the induction sensor of magnetic field

“…The analysis seeks to explain the high sensitivity of the parameters observed typically in the noise characterization of extremely low-noise devices [14]. Derived analytical formulas describe errors in the four-noise parameters, the input reflection coefficient, and gain factor of the two-port tested.…”

“…(14) into (13) we obtain an expression for G m , which does not depend on the frequency. In this case the order of equation and its unwieldiness do not make it possible to find the parameters of RC-links and A of the preamplifier (the remaining parameters of HWIT are considered the given ones) in the common form.°U We find the unknown values RC and A on the basis of the following considerations.…”

Figures of uncertainty for noise measurements

“…While the measurement with use of a noise diode appears to be straightforward, measurement results are usually taken for granted and hardly questioned. A systematic error analysis has been performed in [3] by considering the limited accuracy of the reflection coefficients of the heat source and the receiver reflection coefficients as the main causes of errors. Other sources of systematic errors are uncertainties of the excess noise ratio (ENR) of the noise source, the scattering parameters, in particular the output mismatch, of the DUT and non-linearity of the noise-receiver [1,4].…”