Pick the Right Source: Reliable Network Analyzers Starts with a Clean Signal
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For traditional measurements like S-parameters and gain, network analyzers can easily perform highly accurate measurements. It does so by sampling the test signal before and after it reaches the device under test (DUT) and using vector error correction to account for errors from cables and connectors. Because the input and output frequencies are the same, small discontinuities from the signal source are ratioed out and do not significantly affect the measurement.
However, modern designs containing amplifiers and frequency converters often require network analyzers to perform frequency-offset measurements, with sources and receivers tuned to different frequencies. Transponders for satellite and wireless applications contain thousands of internal paths, and it can take weeks to perform all the required tests. Both phase and amplitude response are important for device characterization. When characterizing frequency converters with internal local oscillators, phase noise in the test system and the DUT can contribute to phase errors. If the results include phase errors, it’s impossible to know whether the phase noise came from the network analyzer or the DUT.