Balanced non-reflection band-pass filter

Abstract

The invention relates to a balanced type non-reflection band-pass filter, which comprises a differential band-pass filter and an absorption network, comprising two pairs of differential input and output ports, two pairs of quarter-wavelength input and output coupling feeder lines, a half-wavelength center transmission line located between the two pairs of quarter-wavelength input and output coupling feeder lines, and a half-wavelength transmission line connected to the tail ends of the quarter-wavelength input and output coupling feeder lines. The absorption network comprises a pair of first absorption resistors loaded at the input end, a pair of quarter-wavelength short-circuit branches loaded at the tail ends of the first absorption resistors, a pair of second absorption resistors loaded at the tail end of the quarter-wavelength input coupling feeder line, and a half-wavelength transmission line of which the two ends are respectively connected to the tail ends of the second absorption resistors; the quarter-wavelength input coupling feeder line is also used as a quarter-wavelength transmission line in the absorption network. Benefited from the selection of a three-wire coupling structure and the proposal of a fusion working mechanism, the problem of circuit size is effectively solved, and the miniaturization design is realized.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to a balanced non-reflection band-pass filter. Background technique [0002] As a key frequency-selective component in a microwave system, traditional radio frequency filters can transmit signals in a specific frequency spectrum without distortion under ideal conditions, and completely suppress interference signals outside the frequency band, but the energy outside the traditional filter band is reflected state, the reflection of reflected energy back to the source will cause unavoidable interference, and there are certain limitations. Usually additional isolators and attenuators are used to alleviate the problem of interference from reflected energy outside the filter band. However, they will inevitably increase the volume of the system, bring additional losses, and are not easy to integrate. Therefore, starting from the requirements of high stability and high inte...

AI Technical Summary

Problems solved by technology

The untransmitted out-of-band reflection energy is dissipated by the absorption network loaded by the input port, but when the absorption network and the bandpass part cannot be completely complementary matched, its out-of-band mismatched frequency band will lead to a limited reflection-free bandwidth

At the same time, multiple absorption networks are usually used in parallel to connect multiple bandpass resonant units to obtain multi-order designs to improve passband selectivity, resulting in excessive design size

In addition, the bandwidth relationship between the bandpass part, the absorption network part and the differential mode bandpass filter has not been discussed in detail in the previous design

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