CN101043096A - Low-pass filter with wide cut-off bandwidth - Google Patents
Low-pass filter with wide cut-off bandwidth Download PDFInfo
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- CN101043096A CN101043096A CN 200610060020 CN200610060020A CN101043096A CN 101043096 A CN101043096 A CN 101043096A CN 200610060020 CN200610060020 CN 200610060020 CN 200610060020 A CN200610060020 A CN 200610060020A CN 101043096 A CN101043096 A CN 101043096A
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- wide cut
- pass filter
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Abstract
A wide cut-off bandwidth low filter includes input end, output end, high impedance transmission line, the first low impedance transmission line, the second low impedance transmission line, and short transversal. The input end is used to feed-in electromagnetic wave signal, the output end is used to feed-out the electromagnetic wave signal. The high impedance transmission line includes the first connecting end which is electric connected with the input end, and the second connecting end which is electric connected with the output end. The first low impedance transmission line includes the third connecting end which is electric connected with the first connecting end, and the first plough end. The second low impedance transmission line includes the forth connecting end which is electric connected with the second connecting end, and the second plough end. The short transversal includes the fifth connecting end which is electric connected between the first connecting end and the second connecting end, and the third plough end. The wide cut-off bandwidth low filter in the invention can increase the cut-off bandwidth of the wide cut-off bandwidth low filter by the additional transmission zero generated by the short transversal, so the filter performance of the wide cut-off bandwidth low filter can be enhanced.
Description
[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 Area Network) agreement.This 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 this agreement 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 the indispensable high frequency assembly in the mobile communication product, and its major function is used for crossover frequency,, blocks the signal of other frequencies by the signal of some frequencies that is.Desirable filter characteristic should be passband undamped and in cut-off frequency decay infinitely great, the saltus step of passband and cut-off frequency should be precipitous as much as possible.In the radio-frequency module (Radio Frequency Module) of IEEE802.11b/g product, partly assembly still has generation or receives the unnecessary signal ability of (being called noise) in the both sides of nearby pass (2.45GHz).This harmonic wave produces many negative influences to communication products easily.Outside for product, can produce as problems such as electromagnetic interference (EMI)s, for product inside, then can cause the signal quality of emission/reception not good, therefore the performance of product is greatly affected.Think the filtering performance that improves filter, the cut off band width of filter need be designed greatly as far as possible usually, so that it can effectively suppress the passband external noise.
[summary of the invention]
For solving the deficiency that above-mentioned prior art exists, a kind of low-pass filter with wide cut-off bandwidth need be provided, this low-pass filter with wide cut-off bandwidth has bigger cut off band width to improve the filtering performance of filter.
A kind of low-pass filter with wide cut-off bandwidth comprises input, output, high-impedance transmission line, the first Low ESR transmission line, the second Low ESR transmission line, and stub.Input is used for the feed-in electromagnetic wave signal, and output is used to feed out electromagnetic wave signal.High-impedance transmission line comprises first link that electrically connects with input, and second link that electrically connects with output.The first Low ESR transmission line comprises the 3rd link that electrically connects with first link, and first open end.The second Low ESR transmission line comprises the 4th link that electrically connects with second link, and second open end.Stub comprises the 5th link that is electrically connected between first link and second link, and the 3rd open end.
Low-pass filter with wide cut-off bandwidth in the embodiment of the present invention can produce extra transmission zero by stub, with the cut off band width of increase low-pass filter with wide cut-off bandwidth, thus the filtering performance of enhancing low-pass filter with wide cut-off bandwidth.
[description of drawings]
Fig. 1 is the structural representation of the low-pass filter with wide cut-off bandwidth in the embodiment of the present invention.
Fig. 2 is the resolution chart of the low-pass filter with wide cut-off bandwidth in electromagnetical analogies gained an embodiment of the present invention.
Fig. 3 is the structural representation of the low-pass filter with wide cut-off bandwidth in another execution mode of the present invention.
Fig. 4 is the resolution chart of the low-pass filter with wide cut-off bandwidth in another execution mode of electromagnetical analogies gained the present invention.
[embodiment]
See also Fig. 1, be depicted as the structural representation of the low-pass filter with wide cut-off bandwidth 10 in an embodiment of the present invention.
In the present embodiment, low-pass filter with wide cut-off bandwidth 10 comprises input 100, output 120, high-impedance transmission line 140, the first Low ESR transmission line 160, the second Low ESR transmission line 180, and stub (Stub) 190.
In the present embodiment, stub 190 is a rectangle.Stub 190 comprises the 5th link 192 that is electrically connected between first link 142 and second link 144, and the 3rd open end 194.Gap 200 is relative with the 3rd open end 194 of stub 190.
In the present embodiment, the length of high-impedance transmission line 140 is 10.85 millimeters (mm), and width is 0.23 millimeter.The length of the first Low ESR transmission line 160 and the second Low ESR transmission line 180 and width are respectively 4.55 millimeters and 1.65 millimeters, and the length of stub 190 and width are respectively 3.23 millimeters and 0.38 millimeter.
See also Fig. 2, be depicted as the resolution chart of the low-pass filter with wide cut-off bandwidth 10 in electromagnetical analogies gained an embodiment of the present invention.Transverse axis is represented the frequency (unit: GHz) by the signal of low-pass filter with wide cut-off bandwidth 10 among the figure, the longitudinal axis represents that (unit: dB), the quadrant district comprises the amplitude of the scattering parameter (S-parameter:S11) of the amplitude of scattering parameter (S-parameter:S21) of transmission and reflection to amplitude.The scattering parameter of transmission (S21) represents that its corresponding mathematical function is: power output/input power (dB)=20 * Log|S21| by the pass between the power output of the input power of the signal of low-pass filter with wide cut-off bandwidth 10 and signal.In the signals transmission of low-pass filter with wide cut-off bandwidth 10, the part power of signal is reflected back toward signal source.The power that is reflected back toward signal source is called reflection power.Pass between the input power of the signal by low-pass filter with wide cut-off bandwidth 10 and the reflection power of signal, its corresponding mathematical function is: reflection power/incident power (dB)=20 * Log|S11|.
As shown in Figure 2, the low-pass filter with wide cut-off bandwidth in an embodiment of the present invention 10 has good filtering performance.From curve | S21| can be observed, and 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 | S11| can be observed, and the signal reflex loss absolute value in the passband frequency range is greater than 10, and outside the passband frequency range, then signal reflex loss absolute value is less than 10.Low-pass filter with wide cut-off bandwidth 10 in an embodiment of the present invention can produce two transmission zero A and transmission zero B by the virtual short that stub 190 is produced, thereby make low-pass filter with wide cut-off bandwidth 10 can reach 12GHz, and the edge effect that the open end 194 by stub 190 is produced produce the rate ripple performance that equivalent capacity improves low-pass filter with wide cut-off bandwidth 10 in the cut off band width at-25dB place.
See also Fig. 3, be depicted as the structural representation of the low-pass filter with wide cut-off bandwidth 20 in another execution mode of the present invention.
In the present embodiment, low-pass filter with wide cut-off bandwidth 20 is stub 290 for trapezoidal with the difference of low-pass filter with wide cut-off bandwidth 10, and stub 290 will be lacked than the length of stub 190.The width of the 3rd open end 294 of stub 290 is wide than the width of the 5th link 292.
In the present embodiment, the length of stub 20 is 2.81 millimeters, and the width of its 3rd open end 294 is 0.38 millimeter.Other each length and width partly is all identical with low-pass filter with wide cut-off bandwidth 10.
See also Fig. 4, be depicted as the resolution chart of the low-pass filter with wide cut-off bandwidth 20 in another execution mode of electromagnetical analogies gained the present invention.As shown in Figure 4, the low-pass filter with wide cut-off bandwidth 20 in another execution mode of the present invention has good filtering performance.From curve | S21| can be observed, and 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 | S11| can be observed, and the signal reflex loss absolute value in the passband frequency range is greater than 10, and outside the passband frequency range, then signal reflex loss absolute value is less than 10.Low-pass filter with wide cut-off bandwidth 20 in another execution mode of the present invention can produce two transmission zero C and transmission zero D by the virtual short that stub 290 is produced, thereby make low-pass filter with wide cut-off bandwidth 20 can reach 11.5GHz, and the edge effect that the open end 294 by stub 290 is produced produce the rate ripple performance that equivalent capacity improves low-pass filter with wide cut-off bandwidth 20 in the cut off band width at-25dB place.
Low-pass filter with wide cut-off bandwidth 10 in the embodiment of the present invention and 20 can produce extra transmission zero B and transmission zero C respectively by stub 190 and 290 makes low-pass filter with wide cut-off bandwidth 10 and 20 cut off band width in-25dB place increase to 12GHz and 11.5GHz respectively, thereby increases the filtering performance of filter 10 and 20.
Claims (10)
1. low-pass filter with wide cut-off bandwidth is characterized in that comprising:
Input is used for the feed-in electromagnetic wave signal;
Output is used to feed out electromagnetic wave signal;
High-impedance transmission line comprises first link that electrically connects with described input, and second link that electrically connects with described output;
The first Low ESR transmission line comprises the 3rd link that electrically connects with described first link, and first open end;
The second Low ESR transmission line comprises the 4th link that electrically connects with described second link, and second open end; And
Stub comprises the 5th link that is electrically connected between described first link and described second link, and the 3rd open end.
2. low-pass filter with wide cut-off bandwidth as claimed in claim 1 is characterized in that described input and described output are 50 ohm of matched impedances of described low-pass filter with wide cut-off bandwidth.
3. low-pass filter with wide cut-off bandwidth as claimed in claim 1 is characterized in that described input and described output are positioned at same straight line.
4. low-pass filter with wide cut-off bandwidth as claimed in claim 1 is characterized in that described first Low ESR transmission line and the described second Low ESR transmission line be arranged in parallel.
5. low-pass filter with wide cut-off bandwidth as claimed in claim 4 is characterized in that described first Low ESR transmission line and the relative gap that forms of the described second Low ESR transmission line.
6. low-pass filter with wide cut-off bandwidth as claimed in claim 5 is characterized in that described gap is relative with described the 3rd open end.
7. low-pass filter with wide cut-off bandwidth as claimed in claim 1 is characterized in that described stub is trapezoidal.
8. low-pass filter with wide cut-off bandwidth as claimed in claim 7 is characterized in that the width of more described the 5th link of width of described the 3rd open end is wide.
9. low-pass filter with wide cut-off bandwidth as claimed in claim 1 is characterized in that described stub is a rectangle.
10. low-pass filter with wide cut-off bandwidth as claimed in claim 1 is characterized in that the described first Low ESR transmission line is identical with the length and the width of the described second Low ESR transmission line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200610060020 CN101043096A (en) | 2006-03-22 | 2006-03-22 | Low-pass filter with wide cut-off bandwidth |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200610060020 CN101043096A (en) | 2006-03-22 | 2006-03-22 | Low-pass filter with wide cut-off bandwidth |
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| CN101043096A true CN101043096A (en) | 2007-09-26 |
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| CN 200610060020 Pending CN101043096A (en) | 2006-03-22 | 2006-03-22 | Low-pass filter with wide cut-off bandwidth |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101540426B (en) * | 2008-03-18 | 2013-01-09 | 鸿富锦精密工业（深圳）有限公司 | Low pass filter |
| CN104022319A (en) * | 2014-05-10 | 2014-09-03 | 中国计量学院 | Adjustable low-pass filter with wide stop band function |
| CN109786906A (en) * | 2019-03-15 | 2019-05-21 | 深圳市普威技术有限公司 | A kind of filter based on coplanar waveguide transmission line |
| CN111418193A (en) * | 2017-12-06 | 2020-07-14 | 三菱电机株式会社 | Signal transmission system |
-
2006
- 2006-03-22 CN CN 200610060020 patent/CN101043096A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101540426B (en) * | 2008-03-18 | 2013-01-09 | 鸿富锦精密工业（深圳）有限公司 | Low pass filter |
| CN104022319A (en) * | 2014-05-10 | 2014-09-03 | 中国计量学院 | Adjustable low-pass filter with wide stop band function |
| CN111418193A (en) * | 2017-12-06 | 2020-07-14 | 三菱电机株式会社 | Signal transmission system |
| CN111418193B (en) * | 2017-12-06 | 2022-09-23 | 三菱电机株式会社 | Signal transmission system |
| CN109786906A (en) * | 2019-03-15 | 2019-05-21 | 深圳市普威技术有限公司 | A kind of filter based on coplanar waveguide transmission line |
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