Millimeter-wave VNA Calibration using a CMOS Transmission Line with Distributed Switches

This paper presents a single-element VNA electronic calibration (E-Cal) technique implemented in CMOS technology. The structure employs a transmission line (t-line) loaded with twenty distributed switches whose impedance states can be independently modulated during S-parameter measurements. An algorithm that leverages the implementation concepts from the one-port offset-shorts and the two-port Line-Reflect-Reflect-Match (LRRM) calibrations and takes advantage of the loading periodicity and the structure layout symmetry is developed. The calibration method is justified using a 65-nm CMOS test chip and the measurement results are compared with on-chip one-tier TRL calibration using both passive and active devices up to 67 GHz.