Millimeter-Wave Device Characterization Under Wideband Modulated Signals Using Vector Network Analyzer Frequency Extenders

This letter presents an innovative frequency extender based measurement system designed for the comprehensive characterization of millimeter-wave devices under both continuous-wave (CW) and modulated signal excitation. In addition to traditional CW-based measurement systems consisting of Vector Network Analyzers (VNAs) and VNA frequency extenders, the proposed system integrates an Intermediate Frequency (IF) Vector Signal Generator (VSG) and IF Vector Signal Analyzers (VSAs). During modulated signal testing, the IF VSG feeds the VNA frequency extender, enabling the generation of RF-modulated signals at the device-under-test (DUT) reference plane without the need for a mixer. Concurrently, the IF VSAs are connected to the VNA frequency extenders, facilitating the capture of wideband modulated signals at the DUT input and output reference planes. Additionally, the proposed system incorporates a novel Iterative Learning Control (ILC) algorithm formulated to linearize frequency multipliers (FMs) within VNA frequency extenders ensuring error-free RF modulated signal generation at the DUT input reference plane. To validate the proposed measurement system, proof-of-concept experiments were conducted at V-band (around 57.6 GHz) using an Oleson Microwave Labs (OML) VNA frequency extender. The novel ILC algorithm was employed to linearize the FM within the OML frequency extender, enabling the mixer-less generation of 256 QAM orthogonal frequency division multiplexing signals with modulation bandwidths up to 800 MHz. The measurement results showcase exceptional signal integrity achieved by the proposed system and enabled by the proposed ILC algorithm, achieving an adjacent channel power ratio and error vector magnitude at the DUT input reference plane of 51.6/48.7 dBc and 1.2%, respectively, when using an 800 MHz test signal case.