Diode-Based Wideband Harmonic Generation for Future Nonlinear Sensing Applications

An essential element in advancing next-generation RF systems and sensing applications through nonlinear sensing technology is the efficient production of harmonics at gigahertz (GHz) frequencies. This research offers a comprehensive theoretical and practical analysis of diode-based harmonic generators, specifically focusing on Schottky, varactor, and step recovery diodes. The study proposes time-domain current equations to predict harmonic amplitudes under various input voltages and biasing conditions, considering the distinctive resistive and capacitive nonlinearities of the diodes. The theoretical models are validated using fabricated prototypes, which demonstrate wideband harmonic production for a 1-GHz input signal with a frequency-modulated sweep spanning 600 MHz in total bandwidth. The measured average output power variation is ±3.4 dBm for SMS7630 and ±5.2 dBm for SMV1213. Beyond offering insights into impedance matching and design optimization, the results underscore the diodes’ suitability for low-power and batteryless applications. By providing a robust physical foundation for enhancing harmonic generation efficiency, this work aspires to drive the development of state-of-the-art RF systems and components.