A Laboratory-Validated Predictive Design Approach for Carbon Nanotube 30/60 GHz MMIC Frequency Doubler

This letter presents a laboratory-level, closed-loop, on-wafer predictive design methodology for emerging-device monolithic microwave integrated circuits (MMICs), enabling rapid prototyping under material/process variability without a commercial process design kit (PDK). The flow integrates broadband nonlinear device modeling, test-structure-based electromagnetic (EM) back-calibration of the passive structure, and EM/circuit co-simulation to predict impedance matching and harmonic generation. A compact zero-bias 30/60 GHz frequency doubler using aligned carbon nanotube (A-CNT) Schottky diodes on high-resistivity silicon (HR-Si) validates the approach. The prototype occupies 1.3 mm2and achieves a minimum conversion loss (CL) of 15 dB with −1.9 dBm output power at 60 GHz, representing a clear performance improvement compared with previously reported CNT doublers. The close agreement between simulation and measurement across the intended band validates the method for mm-wave circuit development on emerging platforms.