PROJECT TITLE :

Analysis of Weakly Nonlinear Effect for Varactor-Tuned Bandpass Filter

ABSTRACT:

This paper presents a general analytical approach to accurately predict the nonlinear distortion of varactor-tuned bandpass filters (BPFs) with arbitrary topology. The linearized circuit and its admittance matrix are derived to study the nonlinear behavior by means that of the Volterra-series illustration. The effects on third-order intermodulation distortion are characterised for the principal filter parameters like tunable resonator configuration, susceptance slope, fractional bandwidth, unloaded quality factor, and filter topology. The theoretical analysis indicates that -sort varactor-tuned BPFs possess a better linearity property thanks to its giant susceptance slope and the fractional bandwidth also plays a dominant role in the generation of nonlinearities. This analysis conjointly reveals that the nonlinear distortion will be further reduced by source–load coupling for the primary time. The analytical results are absolutely coincident with the harmonic-balance simulations using pc-aided design varactor model. A 2-pole 1.0–one.3-GHz tunable BPF with a relentless bandwidth of one zero five MHz is fabricated and measured to validate the theory.