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Direct comprehensive design method for band-pass domain of acoustic wave filter

A technology of acoustic filter and comprehensive design, which is applied in the direction of impedance network, digital technology network, electrical components, etc., can solve the problems of large differences in the far out-of-band, and achieve wide application range, simple and clear calculation process, and high accuracy of calculation results Effect

Pending Publication Date: 2021-10-22
NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD
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Problems solved by technology

Alfred Gimenez et al. proposed a low-pass to band-pass acoustic wave filter synthesis in the article "General Synthesis Methodology for the Design of Acoustic Wave Ladder Filters and Duplexers" in 2018 method, the main design idea is to equivalent the series resonator and parallel resonator to non-resonant nodes, and give the corresponding equivalent circuit, based on Chebyshev comprehensive calculation of the equivalent circuit parameters and then convert it into a low-pass BVD model Circuit parameters, and finally converted to band-pass BVD (Butterworth-Van Dyke, Butterworth Van Dyke) model circuit parameters, however, in this method, the reactance in the equivalent circuit corresponding to the non-resonant node is a frequency-invariant component, so The comprehensive results only have high accuracy near the center frequency f0, and the difference is large outside the far band.
In the article "Synthesis of Ladder-Type Acoustic Filters in the Band-Pass Domain" in 2017, IuliiaEvdokimova et al. proposed a method for directly synthesizing acoustic filters in the band-pass domain. The core is to construct a Chebyshev function suitable for direct synthesis in the band-pass domain according to the filter characteristics. This method avoids the disadvantage of using non-frequency variable reactance in the low-pass domain synthesis, but the method in this paper is only suitable for acoustic filters with symmetrical structures. comprehensive

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  • Direct comprehensive design method for band-pass domain of acoustic wave filter
  • Direct comprehensive design method for band-pass domain of acoustic wave filter
  • Direct comprehensive design method for band-pass domain of acoustic wave filter

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] use figure 2 As shown in the topology, the filter order N=7, the passband frequency range is [2402MHz, 2482MHz], the out-of-band zero positions are [2510MHz, 2350MHz, 2525MHz, 2359MHz, 2525MHz, 2350MHz, 2510MHz], and the return loss IL =18dB.

[0061] The transmission polynomial P(ω), reflection polynomial F(ω), and denominator polynomial E(ω) are calculated according to the bandpass domain Chebyshev polynomial:

[0062] F(ω)=ω 7 -0.508ω 6 +1.78ω 5 -0.81jω 4 +0.91ω 3 -0.34jω 2 +0.1163ω-0.0236j,

[0063] P(ω)=ω 7 -0.798ω 6 +11.8ω 5 -11.04jω 4 +46.8322ω 3 -49.29jω 2 +61.75ω-71.524j,

[0064] E(ω)=ω 7 +(1.958-0.508j)ω 6 +(3.699-1.011j)ω 5 +(4.04-1.82j)ω 4 +(3.569-1.921j)ω 3 +(2.1149-1.5558j)ω 2 +(0.848-0.803j)ω+(0.1602-j0.2385).

[0065] Further, calculate the filter input impedance according to F(ω), P(ω), E(ω) Then calculate the BVD model parameters of each series-parallel resonator:

[0066]

[0067]

[0068] Finally, the filter frequency ...

Embodiment 2

[0070] use image 3 The topology shown, the filter order N=8, the passband frequency range is [2496MHz, 2690MHz], the out-of-band zero positions are [2450MHz, 2750MHz, 2460MHz, 2740MHz, 2465MHz, 2745MHz, 2455MHz, 2755MHz], the echo Loss IL = 18dB.

[0071] The transmission polynomial P(ω), reflection polynomial F(ω), and denominator polynomial E(ω) are calculated according to the bandpass domain Chebyshev polynomial:

[0072] F(ω)=ω 9 +0.724ω 8 -2.365jω 7 -1.6387jω 6 +1.8781ω 5 +1.2127jω 4 -0.5531ω 3 -0.3114jω 2 +0.042ω+0.0152,

[0073] P(ω)=ω 9 +0.6432ω 8 -9.2767jω 7 -6.7157jω 6 +32.3605ω 5 +25.8206jω 4 -50.2854jω 3 -43.4729jω 2 +29.3552ω+27.1307,

[0074] E(ω)=ω 9 +(1.0237-0.037j)ω 8 +(0.9425+0.128j)ω 7 +(0.739-0.265j)ω 6 +(0.326-0.427j)ω 5 +(0.246-0.426j)ω 4 +(0.658-0.268j)ω 3 +(0.868-0.141j)ω 2 +(1.012-0.019j)ω+(0.970-0.066j).

[0075] Further, calculate the filter input impedance according to F(ω), P(ω), E(ω) Then calculate the BVD model param...

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Abstract

The invention discloses a direct comprehensive design method for a band-pass domain of an acoustic wave filter, is suitable for symmetric and asymmetric topological structures of any order, and belongs to the technical field of basic electrical elements. The method comprises the following steps: firstly, converting a Chebyshev polynomial from low pass to band pass; deriving a transmission polynomial, a reflection polynomial and a denominator polynomial according to a band-pass domain Chebyshev polynomial, and calculating input impedance and admittance; and finally, according to the input impedance and admittance, calculating the BVD model parameters of the series resonator and the parallel resonator step by step to acquire acoustic wave filter design parameters and the frequency response curve. According to the invention, the calculation process is simple and clear and high in accuracy.

Description

technical field [0001] The invention relates to filter synthesis design technology, in particular to a direct synthesis design method in the band-pass domain of an acoustic wave filter, which belongs to the technical field of basic electrical components. Background technique [0002] The rapid development of communication systems puts forward higher and higher requirements on the size and performance of filters. Thin film bulk acoustic wave filter has been widely used in various communication systems due to its advantages of small size, low insertion loss and high square coefficient. How to design thin film bulk acoustic filter efficiently and quickly becomes the key. [0003] At present, the research on the synthesis methods of traditional cavity, dielectric, microstrip and other filters has been quite mature, but the research on the synthesis of acoustic filters is still less. Alfred Gimenez et al. proposed a low-pass to band-pass acoustic wave filter synthesis in the art...

Claims

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Application Information

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IPC IPC(8): H03H17/00
CPCH03H17/00H03H2017/0072
Inventor 王亚宁赵洪元
Owner NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD
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