Filter and communication equipment

Abstract

The invention discloses a filter and communication equipment. The filter comprises a shell and a filtering branch, the shell has a first direction and a second direction which are perpendicular to each other; the filtering branch is arranged on the shell and consists of ten filtering cavities which are coupled in sequence; the first filtering cavity and the third filtering cavity of the filtering branch are in inductive cross coupling to form an inductive cross coupling zero point of the filtering branch; capacitive cross coupling elements are respectively arranged between the third filtering cavity and the fifth filtering cavity of the filtering branch, between the fifth filtering cavity and the seventh filtering cavity of the filtering branch and between the seventh filtering cavity and the ninth filtering cavity of the filtering branch, so that three capacitive cross coupling zero points of the filtering branch are formed; the bandwidth range of the filtering branch is 3600MHz-3800MHz. Through the mode, cross coupling zero points are respectively generated at the passband high end and the passband low end, and the out-of-band rejection performance of the filter can be improved.

Description

technical field [0001] The present application relates to the technical field of communication, in particular to a filter and a communication device. Background technique [0002] In the mobile communication system, the required signal is modulated to form a modulated signal, which is carried on a high-frequency carrier signal, transmitted to the air through the transmitting antenna, and the signal in the air is received through the receiving antenna. Among the signals received by the receiving antenna, not only Include the desired signal, but also include other frequency harmonics, noise signals. For the signal received by the receiving antenna, it is necessary to use a filter to filter out unnecessary harmonics and noise signals. Therefore, the designed filter must precisely control its upper limit frequency and lower limit frequency in order to maintain a high degree of isolation from signals outside the passband. [0003] The inventors of the present application have f...

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Problems solved by technology

[0003] The inventors of the present application have found in the long-term research and development work that the setting of the coupling zero point of the existing filter is unreasonable, which makes the out-of-band suppression characteristics of the filtering branch poor, and it is difficult to achieve a high degree of out-of-band signal isolation

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