Chained low-pass filtering circuit

Abstract

The invention discloses a chained low-pass filtering circuit. The circuit structurally comprises an inductor and a capacitor. The Butterworth flattest amplitude-frequency characteristic and the Chebyshev optimal out-of-band rejection characteristic are mainly utilized, a chained low-pass filter is a compromise of a Butterworth filter and a Chebyshev filter, and different responses are given under the same order. Compatibility of the flattest amplitude-frequency characteristic and the optimal out-of-band rejection characteristic of design of the filter is effectively achieved, and it can be ensured that a passive filter can obtain an optimal filtering effect. The important effect of a chained function is that a bridge is set up between the flattest amplitude-frequency characteristic of the Butterworth function and the traditional Chebyshev approximate high out-of-band rejection characteristic. The chained low-pass filtering circuit can be widely used on WCDMA mobile communication power amplifiers, radar antennas and other places having strict requirements for signal performance, out-of-band noise can be restrained, and stability of the electronic circuit is improved.

Description

technical field [0001] The invention belongs to the field of communication and electronic application, especially has important application in filter and matching network. Background technique [0002] In recent years, a series of researches on filter circuits have been carried out at home and abroad. A lot of research results have been obtained, especially in mobile communication technology, the filter circuit can effectively solve the problem of large noise outside the passband of the system when used in the front end of the power amplifier and the feeder part of the radar antenna. However, its design structure can only be used in a specific frequency band, and the bandwidth is small, which makes the system larger and less versatile. At the same time, due to the problem of its circuit structure, the traditional low-pass filter circuit is extremely sensitive to temperature, which cannot overcome the compatibility problem of the flatst amplitude-frequency characteristic and...

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Problems solved by technology

However, its design structure can only be used in a specific frequency band, and the bandwidth is small, which makes the system larger and less versatile

At the same time, due to the problem of its circuit structure, the traditional low-pass filter circuit is extremely sensitive to temperature, which cannot overcome the compatibility problem of the flatst amplitude-frequency characteristic and the best out-of-band suppression characteristic of filter design, and its applicability is greatly limited.

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