Suppression of Unwanted Harmonics Using Integrated Complementary Split-Ring Resonators in Nonlinear Transmission Line Frequency Multipliers

Inspired by the distributed nature of nonlinear transmission lines (NLTLs), a novel filtering method that integrates the filter stages within the NLTL periodic structure is introduced to suppress unwanted signals. To implement the filter, compact complementary split-ring resonators are designed and included in a coplanar waveguide-based NLTL frequency doubler. Analytical derivations for the filter design and prediction of the dispersion characteristics are presented. Measurement results are reported to validate the efficiency of the method demonstrating improvement in third harmonic suppression and reduced sensitivity to the variation of the input voltage level.