Active probes for network analysis within 70-230 GHz

This paper presents a vector network analyzer system for the 70-230-GHz ban dwidth. The instrument employs active probes for millimeter-wave signal gen eration and detection, and for signal delivery to the device-under-test. Mi limeter-wave signals are generated and detected within the active probes us ing an integrated circuit (IC) based on nonlinear transmission lines. The I C contains all elements of an S-parameter test set: a multiplier to generat e the radio-frequency signal, directional couplers to separate the incident and reflected waves, and a pair of high-speed sampling circuits to convert the signals down to lower frequencies. Two-port measurements over the 70-2 30-GHz bandwidth are demonstrated, including those of directional couplers and millimeter-wave high electron-mobility transistors.