A post-fabrication tuning method for a varactor-tuned microstrip filter using the implicit space mapping technique

Abstract

A post-fabrication tuning method that uses the space mapping techniques to directly determine the tuning voltages of a fabricated varactor-tuned microstrip combline filter is presented. The fabricated filter and its measured results replace the simulation based fine model traditionally used in the space mapping technique. Implicit space mapping is implemented to map the circuit based coarse model and the capacitance values of the varactor diodes of the fabricated filter. The proposed design procedure is presented and it is applied to tune a fabricated 4-pole varactor diode tuned microstrip filter with a center frequency of 1 GHz and an absolute bandwidth of 200 MHz.