Compact Cross-coupled Tunable Non-Reciprocal Bandpass Filter using Combline Architecture

Recently, non-reciprocal filters based on time-varying transmission lines (TVTL) have gained in favour. Their operation is based on the time-modulation of spatially separated resonators using sinusoids with incremental phase shifts. An EM simulation of a non-reciprocal bandpass filter created utilising cross-coupled combline architecture is presented in this paper. With the use of a coupling matrix, the design process has been examined, and the circuit exhibits a small, tunable, non-reciprocal bandpass response with improved skirt frequency characteristics appropriate for mobile communication frequency range. The insertion loss, return loss, and isolation all change over the tunability range by 3.6 dB to 4.1 dB, >16 dB, and >17 dB, respectively. These filters can be used in MMIC designs of transmitters, and receivers.