System and method for measuring wideband noise parameters using an impedance generator

A system for measuring noise parameters of a linear device-under-test, the system comprising:

• a noise source for generating a signal;
• an impedance generator coupled to the device-under-test;
• each of the impedance generator and the device-under-test comprising an input and an output, the output of the impedance generator being coupled to the input of the device-under-test, the impedance generator having a plurality of impedance generator settings to generate a plurality of driving-port impedances over a plurality of frequencies when the noise source is applied to the input of the impedance generator;
• a receiver coupled to the output of the device-under-test for measuring noise power of the device-under-test;
• and
• a processor and memory coupled to the impedance generator and the receiver, the processor configured for:
• identifying a plurality of stable driving-port impedances from the plurality of driving-port impedances, each of the plurality of stable driving-port impedances providing a device-under-test that is stable;
• calculating an aggregate driving-port impedance for each of the plurality of stable driving-port impedances to represent a first cascade network at the output of the impedance generator, each aggregate driving-port impedance being based on the difference between the stable driving-port impedance and a pre-determined driving-port impedance, the stable driving-port impedance and the pre-determined driving-port impedance having a common impedance generator setting and a common frequency;
• identifying a minimal set of impedance generator settings for a user-selected frequency range, the minimal set of impedance generator settings comprising four or more impedance generator settings that provide at least one aggregate driving-port impedance being located within each of four linearly independent regions of a Smith Chart over the user-selected frequency range;
• providing the minimal set of impedance generator settings to the impedance generator;
• receiving aggregate noise power measured by the receiver when the impedance generator generates an aggregate driving-port impedance for each of the minimal set of impedance generator settings over the user-selected frequency range;
• and
• calculating the noise parameters of the device-under-test based on the aggregate noise power and a second cascade network at an output of the first cascade network by removing the effect of the second cascade network from the aggregate noise power, each pair of first cascade network and second cascade network providing an ideal through circuit.