Balanced type radio frequency voltage tunable bandpass filter with constant absolute bandwidth

Abstract

Disclosed in the present invention is a balanced radio frequency electrically tunable band-pass filter with constant absolute bandwidth. The band-pass filter comprises a micro strip structure at an upper layer, a medium substrate at a middle layer and grounding metal at a lower layer. The micro strip structure at the upper layer adopts a balanced circuit and comprises four half-wavelength resonators, two input feed networks, two output feed networks, two input ports and two output ports; each of the four half-wavelength resonators comprises a micro strip and a variable capacitance diode with two connected ends; capacitors are loaded at the middles of the first half-wavelength resonator and the third half-wavelength resonator; the second half-wavelength resonator and the fourth half-wavelength resonator are bent and arranged symmetrically; and the whole filter structure is in mirror symmetry. The balanced radio frequency electrically tunable band-pass filter provided by the invention realizes constant absolute bandwidth during centre frequency tuning and can restrain common mode interference and can be used for a reconstructed radio frequency front end of wireless communication.

Description

technical field [0001] The invention relates to a balanced radio frequency electronically adjustable bandpass filter with adjustable center frequency, in particular to a balanced radio frequency electronically adjustable bandpass filter with constant absolute bandwidth that can be applied in multi-band, wideband and reconfigurable radio frequency front-end systems pass filter. Background technique [0002] Modern ultra-wideband radar and wireless communications require high-performance reconfigurable RF front-ends. For example, in the cognitive radio system, in order to fully utilize and integrate various wireless channels and standards, the RF front-end needs to work at different frequencies, which requires a reconfigurable RF front-end with tunable center frequency. As an important part of the reconfigurable RF front-end, RF electronically tuned band-pass filters are receiving increasing attention. In this regard, there have been some research reports, and a variety of d...

AI Technical Summary

Problems solved by technology

[0005] (2) Interference from environmental noise around the system

So far there is no research report on balanced RF electronically tunable filters with absolute bandwidth control and common-mode rejection characteristics

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