A Loss Compensated Tunable Bandpass Filter Based on Parametric Amplification

This paper presents a technique to compensate the intrinsic loss of a tunable resonator, which can then be used to realize tunable bandpass filters (BPFs) with reduced insertion loss (IL). The parasitic losses in a tunable resonator can be compensated by introducing a negative resistance to the resonator through parametric amplification. Based on the proposed technique, a third-order tunable BPF operating between 1.5 to 2 GHz is designed and simulated. The simulated results indicate that the intrinsic loss can be compensated at each operating frequency. The compensated intrinsic losses are 11.9, 9, and 7.2 dB at 1.5, 1.75, and 2 GHz, respectively. In addition, the resulted noise figure, out-of-band rejection, and return loss are all improved when the parametric amplification technique is applied.