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Acoustic wave filter with enhanced rejection

A filter and acoustic technology, applied in impedance networks, electrical components, etc., to solve problems such as excessive loss, high-end distortion of the passband of a bandpass filter, etc.

Active Publication Date: 2018-07-31
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This Bragg resonance can distort the high end of the passband of the bandpass filter, causing excessive loss at these frequencies

Method used

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  • Acoustic wave filter with enhanced rejection
  • Acoustic wave filter with enhanced rejection
  • Acoustic wave filter with enhanced rejection

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Embodiment Construction

[0044] This disclosure describes a design technique that enhances rejection on one or both sides of the passband of an acoustic wave (AW) microwave filter such as surface acoustic wave (SAW), bulk acoustic wave ( BAW), film bulk acoustic resonator (FBAR) or microelectromechanical system (MEMS) filters. The technique uses standard fabrication techniques and can be implemented without changing the overall size of the chip on which the microwave filter resides. This technique is very useful when implemented in a bandgap sequential duplexer. Rejection in adjacent frequency bands has also been increased. Out-of-band frequencies above and below the passband can be suppressed more, which will help prevent unwanted signals from interfering with the performance of the front-end receiver. Narrowband filters / duplexers can be designed, which increases the number of designs for a given piezoelectric material. Acoustic microwave filters can operate at microwave frequencies in the range o...

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Abstract

A narrow-band acoustic filter comprises an input and an output, and at least one acoustic resonator pair coupled between the input and the output. Each of the acoustic resonator pair(s) comprises at least one in-line acoustic resonator and in-shunt acoustic resonator that operate together to create a nominal passband. The acoustic filter further comprises at least one capacitive element in parallel with one of the in-line acoustic resonator and the in-shunt acoustic resonator of each of the acoustic resonator pair(s), thereby sharpening one of a lower edge and an upper edge of the nominal passband.

Description

technical field [0001] This invention relates generally to microwave filters, and more particularly to acoustic microwave filters specifically for narrowband applications. Background technique [0002] Electronic filters have long been used in the processing of electrical signals. Such electronic filters are used, among other things, to select desired electrical signal frequencies from an input signal by passing desired signal frequencies, while blocking or attenuating other undesired electrical signal frequencies. Filters can be divided into low-pass filters, high-pass filters, band-pass filters, and band-stop filters according to general categories, indicating the type of frequency that the filter selectively passes. In addition, filters can be classified by type, such as Butterworth, Chebyshev, inverse Chebyshev, and elliptic, indicating the type of band-shaped frequency response (frequency cutoff characteristic) that the filter provides relative to the ideal frequency r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/64H03H9/54H03H9/56
CPCH03H9/6483H03H9/605H03H9/54H03H9/542H03H9/568
Inventor 库尔特·F·赖恩格雷戈里·L·海伊-希普顿
Owner MURATA MFG CO LTD