Power level control of mm-wave test benches for accurate small and large-signal DUT measurements

In this contribution we describe the accuracy improvement achievable using a vector corrected, power calibrated test-bench when measuring mm-wave non-linear devices. The absence of automatic level control in commercially available network analyzer frequency extenders can result in AM distortion of the transfer characteristic. Moreover, when large-signal mm-wave test-benches are employed (i.e., using multipliers and power meters) the lack of vector correction causes transfer characteristic errors. The usage of power levelled mm-wave VNA test-benches allows to properly measure the true small-signal s-parameter response as well as accurately correct for the impedance mismatch present, providing increased correlation between small and large-signal test-benches response. The accuracy limitation of classical approaches and the improvement achieved by the levelled mm-wave VNA test-bench are validated on a 140GHz power amplifier.