CN1956256A - Band-pass filter - Google Patents

Band-pass filter Download PDF

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Publication number
CN1956256A
CN1956256A CN 200510100770 CN200510100770A CN1956256A CN 1956256 A CN1956256 A CN 1956256A CN 200510100770 CN200510100770 CN 200510100770 CN 200510100770 A CN200510100770 A CN 200510100770A CN 1956256 A CN1956256 A CN 1956256A
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CN
China
Prior art keywords
band
pass filter
band pass
transmission line
public
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Pending
Application number
CN 200510100770
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Chinese (zh)
Inventor
施延宜
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hongfujin Precision Industry Shenzhen Co Ltd
Hon Hai Precision Industry Co Ltd
Original Assignee
Hongfujin Precision Industry Shenzhen Co Ltd
Hon Hai Precision Industry Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Hongfujin Precision Industry Shenzhen Co Ltd, Hon Hai Precision Industry Co Ltd filed Critical Hongfujin Precision Industry Shenzhen Co Ltd
Priority to CN 200510100770 priority Critical patent/CN1956256A/en
Publication of CN1956256A publication Critical patent/CN1956256A/en
Pending legal-status Critical Current

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Abstract

A band-pass filter is feeding electromagnetic wave signal by input end and feeding out electromagnetic wave signal by output end, forming the first transmission line by the first grounding end being electric-connected to input end and the first open circuit end, forming the second transmission line by the second grounding end being electric -connected to output end and the second open circuit end.

Description

Band pass filter
[technical field]
The present invention relates to a kind of high frequency assembly, relate in particular to a kind of filter.
[background technology]
In recent years, because the market demand of mobile communication product heightens, make that the development of radio communication is more rapid, in numerous wireless communication standards, the most noticeable is that U.S.'s Institute of Electrical and Electronics Engineers is (hereinafter to be referred as IEEE) 802.11 WLAN of Zhi Dinging (Wireless Local AreaNetwork) agreement.Described agreement was formulated in 1997, and it not only provides many unprecedented functions on the radio communication, and the solution that provides the wireless communications products that can make various different brands to be communicated with each other.The formulation of wireless local area network protocol has been opened a new milestone for the radio communication development undoubtedly.IEEE 802.11b/g is current standard commonly used in many standards that IEEE formulated, and its working frequency range is 2.45GHz.
Simultaneously filter is an indispensable high frequency assembly one of in the mobile communication product, and its major function is to be used for crossover frequency,, blocks the signal of other frequencies by the signal of some frequencies that is.Desirable filter characteristic should be the passband frequency range undamped and in the decay frequency range decay infinitely great, passband should be precipitous as much as possible to the transition of decay frequency range.In the radio-frequency module (RadioFrequency Module) of IEEE 802.11b/g product, the part assembly especially at frequency multiplication place (near the 5GHz), has generation or receives the unnecessary signal ability of (being called harmonic wave) outside 2.45GHz.This harmonic wave easily produces many negative influences for communication products.Outside for product, can produce problem as electromagnetic interference, for product inside, then can cause the signal quality of emission/reception not good, therefore the performance of product is greatly affected.
In addition, owing to many wireless communications products all develop towards light, thin, short, little direction, so it is corresponding less to require the filter area occupied also to answer.How under the prerequisite of the usefulness of taking into account filter, it is a major challenge of current Design of Filter that simultaneously that filter is shared area reduces.
[summary of the invention]
For solving the deficiency that above-mentioned prior art exists, need provide a kind of band pass filter, to be applied in the mobile communication product.
A kind of band pass filter is arranged on the substrate, and described band pass filter comprises an input, an output, at least one first transmission line and at least one second transmission line.Input is used for the feed-in electromagnetic wave signal, and output is used to feed out electromagnetic wave signal.First transmission line comprises that one is electrically connected at first earth terminal of input, and one first open end.Second transmission line comprises that one is electrically connected at second earth terminal of output, and one second open end, and second open end and first open end be arranged in parallel.
Described band pass filter, not only shared area is little, and has low-loss in the passband frequency range, has high loss in the decay frequency range, and then makes very steep " the transition slope " of formation between passband frequency range and decay band limits.
[description of drawings]
Fig. 1 is the schematic diagram of band pass filter in an embodiment of the present invention.
Fig. 2 is the schematic diagram of band pass filter in another execution mode of the present invention.
Fig. 3 is the schematic diagram of band pass filter in the another execution mode of the present invention.
Fig. 4 is the resolution chart of band pass filter in electromagnetical analogies gained embodiment of the present invention.
[embodiment]
See also Fig. 1, be depicted as the schematic diagram of band pass filter 10 in an embodiment of the present invention.
Band pass filter 10 is arranged on the substrate 20, and it comprises an input 100, an output 120, one first transmission line 140 and one second transmission line 160.
Input 100 is used for the feed-in electromagnetic wave signal, and output 120 is used to feed out electromagnetic wave signal.Input 100 and output 120 are 50 ohm of (ohm) matched impedances of band pass filter 10 simultaneously.
First transmission line 140 is a microstrip transmission line, and it comprises one first earth terminal 141 and one first open end 142.It is unsettled that first earth terminal 141 is electrically connected at input 100, the first open ends 142.First transmission line 140 also comprise one first in addition 143,1 first connecting portion, 144, one first public being with in 145,1 second connecting portion 146 and one first be with 147.First connecting portion 144 publicly was with for 145 and first 143 vertical linking to each other in addition with first, and first open end 142 is arranged at first tyre, 143 and first public being with between 145.Second connecting portion 146 was with in 145 and first for 147 vertical linking to each other with first public being with.First 143 equates with the first public length with 145 in addition haply, and the two is parallel to each other.Be with 147 to be arranged at first 143 and first public being with between 145 in addition in first, and with first tyre 143 and first public be with 145 parallel.First open end 142 is positioned at first with 147 free terminal, and first earth terminal 141 is positioned at first 143 the free terminal in addition.In the present embodiment, first transmission line 140 forms a multi-bended transmission line, and present embodiment can be dwindled its area occupied under the prerequisite that does not influence filter 10 performances.
Second transmission line 160 is a microstrip transmission line, and it comprises one second earth terminal 161 and one second open end 162.It is unsettled that second earth terminal 161 is electrically connected at output 120, the second open ends 162.Second transmission line 160 also comprise one second in addition 163,1 second connecting portion, 164, one second public being with in 165,1 the 3rd connecting portion 166 and one second be with 167.Second connecting portion 164 publicly was with for 165 and second 163 vertical linking to each other in addition with second, and second open end 162 is arranged at second tyre, 163 and second public being with between 165.The 3rd connecting portion 166 was with in 165 and second for 167 vertical linking to each other with second public being with.Second 163 equates with the second public length with 165 in addition haply, and the two is parallel to each other.Be with 167 to be arranged at second 163 and second public being with between 165 in addition in second, and with second tyre 163 and second public be with 165 parallel.Second open end 162 is positioned at second with 167 free terminal, and second earth terminal 161 is positioned at second 163 the free terminal in addition.In the present embodiment, second transmission line 160 forms a multi-bended transmission line, and present embodiment can be dwindled its area occupied under the prerequisite that does not influence filter 10 performances.
In the present embodiment, first transmission line 140 and second transmission line, 160 parallel settings, and the shape of the two, length and width are identical.First earth terminal 141 of first transmission line 140 and second earth terminal 161 of second transmission line 160 are for being provided with in the same direction.
In the present embodiment, first of first transmission line 140 publicly be adjacent to second of second transmission line 160 with 145 and publicly be with 165 to be provided with.Input 100 is connected in first tyre 143, and output 120 is connected in second tyre 163.First transmission line 140 and second transmission line 160 be owing to all have an earth terminal, so the length of the two is 1/4th of its resonant wavelength, further to dwindle the shared area of band pass filter 10.
In the present embodiment, input 100 and output 120 are system impedance, and its length can freely be chosen when design, and its width is 0.53mm, the length of first transmission line 140 is that 17.8mm, width are 0.2mm, and the length of second transmission line 160 is that 17.8mm, width are 0.2mm.The area of entire belt bandpass filter 10 is 15.6mm 2
See also Fig. 2, be depicted as the schematic diagram of band pass filter 12 in another execution mode of the present invention.In the present embodiment, band pass filter 12 is compared with band pass filter 10 shown in Figure 1, it comprises first transmission line 140 of a plurality of parallel settings, wherein first first transmission line 140 be electrically connected at input 120, the N first transmission lines 140 near and be parallel to second transmission line 160.In the present embodiment, first transmission line 140 that is increased the more, then the performance of band pass filter 12 better, but its shared area also can be bigger.So, in actual design, should under the situation that its area occupied allows, suitably increase the quantity of first transmission line 140.
See also Fig. 3, be depicted as the schematic diagram of band pass filter 14 in the another execution mode of the present invention.In the present embodiment, band pass filter 14 is compared with band pass filter 10 shown in Figure 1, it comprises second transmission line 160 of a plurality of parallel settings, wherein first second transmission line 160 near and be parallel to first transmission line, 140, the N second transmission lines 160 and be electrically connected at output 120.In the present embodiment, second transmission line 160 that is increased the more, then the performance of band pass filter 14 better, but its shared area also can be bigger.So, in actual design, should under the situation that its area occupied allows, suitably increase the quantity of second transmission line 160.
See also Fig. 4, be depicted as the resolution chart of band pass filter 10 in electromagnetical analogies gained embodiment of the present invention.Transverse axis represents that (unit: GHz), the longitudinal axis represents that (unit: dB), the quadrant district comprises the scattering parameter (S-parameter:S of transmission to amplitude for frequency by the signal of band pass filter in the embodiment of the present invention 10 among the figure 21) amplitude and the scattering parameter (S-parameter:S of reflection 11) amplitude.Scattering parameter (the S of transmission 21) expression by the signal of band pass filter 10 in an embodiment of the present invention input power and the relation between the power output of signal, its corresponding mathematical function is:
Power output/input power (dB)=20 * Log|S 21|.
In the signals transmission of band pass filter 10, the part power of signal is reflected back toward signal source in embodiment of the present invention.The power that is reflected back toward signal source is called reflection power.Pass between the input power of the signal by band pass filter in the embodiment of the present invention 10 and the reflection power of signal is:
Reflection power/incident power (dB)=20 * Log|S 11|.
As shown in Figure 4, band pass filter 10 has good band pass filter performance in the embodiment of the present invention.From curve | S 21| can be observed, form steep " transition slope " between passband frequency range and decay frequency range, and the insertion loss of the signal in passband frequency range is near 0.Simultaneously from curve | S 11| can be observed, the signal reflex loss absolute value in passband frequency range is greater than 10, and outside the passband frequency range, then signal reflex loss absolute value is less than 10.
Band pass filter 10,12 and 14 in the embodiment of the present invention and since have can be simultaneously as the input 100 and the output 120 of impedance matching, so do not need any impedance matching assemblies such as electric capacity, inductance that add.This measure not only can effectively reduce the shared area of band pass filter 10,12 and 14, and has reduced cost.Simultaneously, band pass filter 10,12 and 14 in the embodiment of the present invention, utilize the arrangement mode of multi-bended transmission line 140,160,180,190 to dwindle area, so it can utilize less transmission line to produce bigger attenuation.Simultaneously as long as distance between change input 100 and the earth terminal 141 and the distance between output 120 and the earth terminal 161, can produce a transmission zero, carry out the ability of effectively constraining with enhancement band filter 10,12 and 14 noises for the decay frequency range.

Claims (16)

1. a band pass filter is arranged on the substrate, and described band pass filter comprises that one is used for the input of feed-in electromagnetic wave signal, and one is used to feed out the output of electromagnetic wave signal; It is characterized in that described band pass filter also comprises:
At least one first transmission line comprises one first earth terminal, is electrically connected at described input, and one first open end;
At least one second transmission line comprises one second earth terminal, is electrically connected at described output, and one second open end, and described second open end and described first open end be arranged in parallel.
2. band pass filter as claimed in claim 1 is characterized in that the parallel setting of described first transmission line and described second transmission line.
3. band pass filter as claimed in claim 1, it is characterized in that described first transmission line also comprises one first tyre, the first public band, and one first connecting portion, described first connecting portion with described first in addition and described first public band is vertical links to each other, and described first open end is arranged between described first tyre and the described first public band.
4. band pass filter as claimed in claim 3, it is characterized in that described first transmission line also comprises band in one first, and second connecting portion of placing with respect to described first connecting portion, described second connecting portion is vertically connected at band in the described first public band and described first.
5. band pass filter as claimed in claim 4 it is characterized in that described first equates haply with the length of the described first public band in addition, and the two is parallel to each other.
6. band pass filter as claimed in claim 5 is characterized in that band is set in parallel between described first tyre and the described first public band in described first.
7. band pass filter as claimed in claim 4 is characterized in that described first open end is positioned at the free terminal of described first band, and described first earth terminal is positioned at the free terminal of described first tyre.
8. band pass filter as claimed in claim 7, it is characterized in that described second transmission line also comprises one second tyre, the second public band, and one the 3rd connecting portion, described the 3rd connecting portion with described second in addition and described second public band is vertical links to each other, and described second open end is arranged between described second tyre and the described second public band.
9. band pass filter as claimed in claim 8 is characterized in that described second transmission line also comprises band in one second, and the 4th connecting portion with respect to described the 3rd connecting portion placement, is vertically connected at band in the described second public band and described second.
10. band pass filter as claimed in claim 9 it is characterized in that described second equates haply with the length of the described second public band in addition, and the two is parallel to each other.
11. band pass filter as claimed in claim 10 is characterized in that band is set in parallel between described second tyre and the described second public band in described second.
12. band pass filter as claimed in claim 11 is characterized in that described second open end is positioned at the free terminal of described second band, described second earth terminal is positioned at the free terminal of described second tyre.
13. band pass filter as claimed in claim 12 is characterized in that the described first public band setting is adjacent to the described second public band.
14. band pass filter as claimed in claim 13 is characterized in that described input is connected in described first in addition.
15. band pass filter as claimed in claim 13 is characterized in that described output is connected in described second in addition.
16. band pass filter as claimed in claim 1 is characterized in that described input and output are 50 ohm of matched impedances of described band pass filter.
CN 200510100770 2005-10-27 2005-10-27 Band-pass filter Pending CN1956256A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN 200510100770 CN1956256A (en) 2005-10-27 2005-10-27 Band-pass filter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN 200510100770 CN1956256A (en) 2005-10-27 2005-10-27 Band-pass filter

Publications (1)

Publication Number Publication Date
CN1956256A true CN1956256A (en) 2007-05-02

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Family Applications (1)

Application Number Title Priority Date Filing Date
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017193340A1 (en) * 2016-05-12 2017-11-16 华为技术有限公司 Filtering unit and filter

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017193340A1 (en) * 2016-05-12 2017-11-16 华为技术有限公司 Filtering unit and filter
US10673111B2 (en) 2016-05-12 2020-06-02 Huawei Technologies Co., Ltd. Filtering unit and filter

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