CN108155885B - Tuning filter - Google Patents
Tuning filter Download PDFInfo
- Publication number
- CN108155885B CN108155885B CN201810027953.5A CN201810027953A CN108155885B CN 108155885 B CN108155885 B CN 108155885B CN 201810027953 A CN201810027953 A CN 201810027953A CN 108155885 B CN108155885 B CN 108155885B
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- microstrip
- tuning
- microstrip line
- varactor
- filter circuit
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- 238000006243 chemical reaction Methods 0.000 claims description 18
- 239000003990 capacitor Substances 0.000 claims description 16
- 230000002093 peripheral effect Effects 0.000 claims description 6
- 230000035945 sensitivity Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 8
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H5/00—One-port networks comprising only passive electrical elements as network components
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a tuning filter, which comprises a tuning control circuit and a microstrip tuning filter circuit, wherein the output end of the tuning control circuit is connected with the tuning end of the microstrip tuning filter circuit, the microstrip tuning filter circuit also comprises a signal input end and a signal output end, the signal input end is used for inputting signals, and the signal output end is used for outputting signals. The microstrip tuning filter circuit can effectively reduce passband loss and improve signal receiving sensitivity.
Description
Technical Field
The present invention relates to in the field of the filter device, in particular a tuned filter.
Background
Super wifi: based on the IEEE802.22 or IEEE802.af protocols, a white band between television channel frequencies is used.
With the rapid development of the modern communication industry, electromagnetic wave signals with various frequencies are propagated in the air. The electromagnetic wave signals can enter the receiving equipment through direct coupling or indirect coupling, so that the quality of the received signals of the wireless receiving system is influenced, the performance of the receiving system is reduced, the quality is deteriorated, information errors or information loss are caused, and communication interruption is seriously caused. It is necessary to add a filter at the front end of the wireless receiving device to suppress these out-of-band interference signals, however, the super wifi device used between the tv channels needs to avoid the tv channels reasonably according to the use environment, so as to avoid co-channel interference, and at the same time, needs to effectively suppress the interference of the tv channel frequency and other wireless signals. While a general filter has a fixed passband bandwidth, it is difficult to change the passband frequency to avoid interference signals. The tuning filter can achieve the effect that the passband frequency is adjustable, a better communication channel is selected according to the interference condition of the use environment, the passband frequency of the tuning filter is adjusted to inhibit surrounding interference signals, the receiving performance is improved, out-of-band interference is prevented from being reduced, and the blocking possibility of a receiving system is reduced.
The general tuning filter is built by adopting discrete components and has a lower frequency band, however, the discrete components are used in a super wifi frequency band (470 MHz-790 MHz), and the Q value of the discrete components affects the passband loss of the tuning filter, so that the passband loss of the tuning filter is larger, and the receiving sensitivity of the system is affected by the higher passband loss.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a tuning filter, and the passband loss can be effectively reduced by using a microstrip tuning filter circuit.
The technical scheme adopted by the invention is as follows: the output end of the tuning control circuit is connected with the tuning end of the microstrip tuning filter circuit, the microstrip tuning filter circuit further comprises a signal input end and a signal output end, the signal input end is used for inputting signals, and the signal output end is used for outputting signals.
Further, the tuning control circuit comprises a main control circuit and a digital-analog conversion circuit, wherein the main control circuit is connected with the digital-analog conversion circuit, and the output end of the digital-analog conversion circuit is connected with the tuning end of the microstrip tuning filter circuit.
Further, the digital-analog conversion circuit is a DAC chip with the model of MCP4725 and peripheral circuits thereof.
Further, the main control circuit is a singlechip and a peripheral circuit thereof.
Further, the microstrip tuning filter circuit comprises a first capacitor, a second capacitor, a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, a first inductor, a second inductor, a third inductor, a first varactor and a second varactor, one end of the first capacitor is used as a signal input end of the microstrip tuning filter circuit, the other end of the first capacitor is connected with one end of a first microstrip line and one end of a third microstrip line, the other end of the third microstrip line is connected with one end of a first inductor and one end of a fourth microstrip line, the other end of the fourth microstrip line is connected with one end of the third inductor and the negative electrode of a first varactor, the negative electrode of the first varactor is connected with the negative electrode of a second varactor, the negative pole of first varactor is connected with the output of tuning control circuit as the tuning end of microstrip tuning filter circuit, the other end of third inductance is connected with the negative pole of second varactor, one end of fifth microstrip, the other end of fifth microstrip is connected with one end of second inductance, one end of sixth microstrip, the other end of sixth microstrip is connected with one end of second microstrip, one end of second electric capacity, the other end of second electric capacity is as the signal output part of microstrip tuning filter circuit, the other end of first microstrip, the other end of second microstrip, the other end of first inductance, the other end of second inductance, the positive pole of first varactor, the positive pole of second varactor ground.
Further, the first microstrip line and/or the second microstrip line are/is microstrip lines with a width of 0.72mm and a length of 15.5 mm.
Further, the third microstrip line and/or the fourth microstrip line and/or the fifth microstrip line and/or the sixth microstrip line are microstrip lines with the width of 0.72mm and the length of 12 mm.
Further, the microstrip tuning filter circuit also comprises a first resistor, a second resistor and a third resistor, the cathode of the first varactor is connected with one end of the first resistor, the other end of the first resistor is connected with one end of the second resistor and one end of the third resistor, the other end of the third resistor is used as a tuning end of the microstrip tuning filter circuit to be connected with the output end of the tuning control circuit, and the other end of the second resistor is connected with the cathode of the second varactor.
The beneficial effects of the invention are as follows:
the invention discloses a tuning filter, which comprises a tuning control circuit and a microstrip tuning filter circuit, wherein the output end of the tuning control circuit is connected with the tuning end of the microstrip tuning filter circuit, the microstrip tuning filter circuit also comprises a signal input end and a signal output end, the signal input end is used for inputting signals, and the signal output end is used for outputting signals. The microstrip tuning filter circuit can effectively reduce passband loss and improve signal receiving sensitivity.
Drawings
The following is a further description of embodiments of the invention, taken in conjunction with the accompanying drawings:
FIG. 1 is a block diagram of one embodiment of a tuned filter of the present invention;
FIG. 2 is a schematic circuit diagram of one embodiment of a digital-to-analog conversion circuit of a tuned filter according to the present invention;
FIG. 3 shows a microstrip tuning of a tuning filter according to the present invention a schematic diagram of one embodiment of a filter circuit;
fig. 4 is a characteristic diagram of a varactor diode.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.
Referring to fig. 1, fig. 1 is a block diagram of a tuning filter according to an embodiment of the present invention, which includes a tuning control circuit and a microstrip tuning filter circuit, wherein an output end of the tuning control circuit is connected to a tuning end of the microstrip tuning filter circuit, the microstrip tuning filter circuit further includes a signal input end and a signal output end, the signal input end is used for inputting a signal, and the signal output end is used for outputting a signal. The microstrip tuning filter circuit can effectively reduce passband loss and improve signal receiving sensitivity.
As a further improvement of the technical scheme, referring to fig. 1, the tuning control circuit comprises a main control circuit and a digital-to-analog conversion circuit, wherein the main control circuit is connected with the digital-to-analog conversion circuit, and the output end of the digital-to-analog conversion circuit is connected with the tuning end of the microstrip tuning filter circuit. The main control circuit is a singlechip and a peripheral circuit thereof. Referring to fig. 2, fig. 2 is a schematic circuit diagram of an embodiment of a digital-to-analog conversion circuit of a tuning filter according to the present invention, wherein the digital-to-analog conversion circuit is a DAC chip U1 of MCP4725 type and its peripheral circuits, and the DAC chip U1 is connected to a main control circuit through i2c_clk and i2c_data. The main control circuit is used for controlling the DAC chip U1 to output corresponding voltage Vout; the digital-analog conversion circuit is used for converting a fixed voltage such as 5V into a continuous voltage of 0-5V (any voltage of 0-5V, and particularly, how much volt depends on an instruction sent by the singlechip).
As a further improvement of the technical solution, referring to fig. 1 and 3, fig. 3 is a schematic circuit diagram of a specific embodiment of a microstrip tuning filter circuit of the tuning filter according to the present invention, where the microstrip tuning filter circuit includes a first capacitor C1, a second capacitor C2, a first microstrip line TL1, a second microstrip line TL2, a third microstrip line TL3, a fourth microstrip line TL4, a fifth microstrip line TL5, a sixth microstrip line TL6, a first inductor L1, a second inductor L2, a third inductor L3, a first varactor D1 and a second varactor D2, one end of the first capacitor C1 is used as a signal input end RF IN of the microstrip tuning filter circuit, the other end of the first capacitor C1 is connected with one end of the first microstrip line TL1 and one end of the third microstrip line TL3, zxfoom TL3 L1 , TL4 , the other end of the fourth microstrip line TL4 is connected with one end of a third inductor L3 and the cathode of a first varactor D1, the cathode of the first varactor D1 is connected with the cathode of a second varactor D2, the cathode of the first varactor D1 is used as the tuning end of a microstrip tuning filter circuit to be connected with the output end of a tuning control circuit, the other end of the third inductor L3 is connected with the cathode of the second varactor D2 and one end of a fifth microstrip line TL5, the other end of the fifth microstrip line TL5 is connected with one end of a second inductor L2 and one end of a sixth microstrip line TL6, the other end of the sixth microstrip line TL6 is connected with one end of a second microstrip line TL2 and one end of a second capacitor C2, the other end of the second capacitor C2 is used as the signal output end RF OUT of the microstrip tuning filter circuit, the other end of the first microstrip line TL1, the other end of the second microstrip line TL2, the other end of the first inductor L1 and the other end of the second inductor L2, the anode of the first varactor diode D1 and the anode of the second varactor diode D2 are grounded. Further, the microstrip tuning filter circuit further comprises a first resistor R1, a second resistor R2 and a third resistor R3, wherein the cathode of the first varactor diode D1 is connected with one end of the first resistor R1, the other end of the first resistor R1 is connected with one end of the second resistor R2 and one end of the third resistor R3, the other end of the third resistor R3 is connected to an output end of the tuning control circuit (in fig. 3, the tuning control circuit outputs Vout to the tuning end of the microstrip tuning filter circuit) as a tuning end of the microstrip tuning filter circuit, and the other end of the second resistor R2 is connected to a cathode of the second varactor diode D2. The frequency tuning of the tuning filter can be realized by controlling the reverse voltages of the first varactor diode D1 and the second varactor diode D2 through the tuning control circuit; the microstrip tuning filter circuit can reduce passband loss and improve out-of-band rejection.
The first varactor diode and the second varactor diode are capacitors with changeable capacitance values, and the capacitance values of the first varactor diode and the second varactor diode are changed to cause the change of the center frequency of a passband of the microstrip tuning filter circuit; therefore, the capacitance value of the varactor can be controlled to control the passband center frequency of the microstrip tuning filter circuit, and the capacitance value change of the varactor is determined by the reverse voltage applied to the reverse end of the varactor, so that the capacitance value of the varactor can be controlled in real time only by reasonably controlling the reverse voltage applied to the reverse end of the varactor. Referring to fig. 4, fig. 4 is a characteristic diagram of a varactor, VR is a reverse voltage of the varactor, CT is a capacitance of the varactor, and as the reverse voltage VR changes, the capacitance CT of the varactor changes accordingly; the direction voltage can be changed within the range of 0-5V, and referring to FIG. 1, the digital-analog conversion circuit can achieve the effect that the output voltage is continuously changed by 0-5V, and the main control circuit controls the digital-analog conversion circuit, so that the desired passband frequency of the filter can be obtained. Referring to fig. 2 and 3, the master control circuit controls the DAC chip to output a voltage of 0-5V through a pair of I2C control lines (I2 c_data, I2 c_clk), the voltage is applied to the negative electrode of the varactor diode in the microstrip tuning filter circuit, the varactor diode is equivalent to a capacitor (the varactor diode Guan Rong values under different reverse voltages are different), and then the passband of the microstrip tuning filter circuit corresponds to a frequency value. For example, if the input of the microstrip tuning filter circuit is a radio frequency signal of 500MHz, the passband center frequency of the microstrip tuning filter circuit must be 500MHz, and when the center frequency of the microstrip tuning filter circuit is 500MHz, the reverse voltage applied to the microstrip tuning filter circuit is 1.2V, then an instruction is required to be sent by the main control circuit to make the DAC chip output a voltage of 1.2V to be applied to the cathode of the varactor diode of the microstrip tuning filter circuit, so that the passband center frequency of the microstrip tuning filter circuit is shifted to 500MHz.
Specifically, referring to fig. 3, the first microstrip line TL1 and/or the second microstrip line TL2 is 0.72mm wide, microstrip line 15.5mm long. The third microstrip line TL3 and/or the fourth microstrip line TL4 and/or the fifth microstrip line TL5 and/or the sixth microstrip line TL6 are microstrip lines with a width of 0.72mm and a length of 12 mm. The size of the microstrip line is obtained by simulation calculation by using ADS software, and the specific acquisition steps are as follows: calculating a beta value corresponding to the inductor according to a formula of 2pi fL=tan beta Z0; where pi is the circumference ratio, f is the passband frequency of the tuned filter circuit (here, the maximum frequency 790M is taken), L is the inductance value, Z0 is the microstrip line characteristic impedance, here, 50 Ω, such as 5.1nH inductance, is taken into the above to obtain β=26.84; the LineCalc tool at ADS is populated with the corresponding data as follows: er=4.5 is the dielectric constant of the microstrip line board, H is the thickness of the microstrip line board, T is the thickness of the surface conductor, freq is the passband frequency of the tuned filter circuit, Z0 is the characteristic impedance of the microstrip line, and e_eff is the calculated β value (e.g., the β value of the 5.1nH inductance described above), where the values of Er, H, T depend on the materials used basically for the microstrip line; after filling data, the size value of the microstrip line can be obtained by converting, for example, an inductance of 5.1nH is converted into a microstrip line with a length of 15.56mm and a width of 0.72mm, and similarly, an inductance of 3.3nH is converted into a microstrip line with a length of 12mm and a width of 0.72 mm.
Referring to fig. 3, the first inductance L1, the second inductance L2, and the third inductance L3 of 82nH of 8.2nH are not converted because the volume of the microstrip line after their conversion may be very large. Therefore, the invention controls the volume of the product on the basis of realizing the adjustable channel frequency, and has simple structure and high integration degree.
The preferred embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the invention, and these equivalent modifications or substitutions are intended to be included within the scope of the present invention as defined in the claims.
Claims (2)
1. The tuning filter is characterized by comprising a tuning control circuit and a microstrip tuning filter circuit, wherein the output end of the tuning control circuit is connected with the tuning end of the microstrip tuning filter circuit, the microstrip tuning filter circuit also comprises a signal input end and a signal output end, the signal input end is used for inputting signals, and the signal output end is used for outputting signals;
the tuning control circuit comprises a main control circuit and a digital-analog conversion circuit, wherein the main control circuit is connected with the digital-analog conversion circuit, and the output end of the digital-analog conversion circuit is connected with the tuning end of the microstrip tuning filter circuit;
the digital-analog conversion circuit is a DAC chip with the model of MCP4725 and a peripheral circuit thereof;
the main control circuit is a singlechip and a peripheral circuit thereof;
the microstrip tuning filter circuit comprises a first capacitor, a second capacitor, a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, a first inductor, a second inductor, a third inductor, a first varactor and a second varactor, wherein one end of the first capacitor is used as a signal input end of the microstrip tuning filter circuit, the other end of the first capacitor is connected with one end of the first microstrip line and one end of the third microstrip line, the other end of the third microstrip line is connected with one end of the first inductor and one end of the fourth microstrip line, the other end of the fourth microstrip line is connected with one end of the third inductor and the negative electrode of the first varactor, the negative electrode of the first varactor is used as an output end of the microstrip tuning filter circuit, the other end of the third inductor is connected with one end of the second varactor, one end of the fifth microstrip line is connected with one end of the first microstrip line, the other end of the second microstrip line is connected with one end of the second microstrip, the other end of the second microstrip is connected with one end of the second microstrip, the other end of the second varactor is connected with the other end of the microstrip tuning filter circuit, and the other end of the second varactor is connected with the other end of the microstrip, the other end of the microstrip filter circuit;
the first microstrip line and/or the second microstrip line are microstrip lines with the width of 0.72mm and the length of 15.5 mm;
the third microstrip line and/or the fourth microstrip line and/or the fifth microstrip line and/or the sixth microstrip line are microstrip lines with the width of 0.72mm and the length of 12 mm.
2. The tuning filter according to claim 1, wherein the microstrip tuning filter circuit further comprises a first resistor, a second resistor and a third resistor, the cathode of the first varactor is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor and one end of the third resistor, the other end of the third resistor is used as a tuning end of the microstrip tuning filter circuit and is connected to an output end of the tuning control circuit, and the other end of the second resistor is connected to the cathode of the second varactor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810027953.5A CN108155885B (en) | 2018-01-11 | 2018-01-11 | Tuning filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810027953.5A CN108155885B (en) | 2018-01-11 | 2018-01-11 | Tuning filter |
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| Publication Number | Publication Date |
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| CN108155885A CN108155885A (en) | 2018-06-12 |
| CN108155885B true CN108155885B (en) | 2023-12-29 |
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| CN201810027953.5A Active CN108155885B (en) | 2018-01-11 | 2018-01-11 | Tuning filter |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105703739B (en) * | 2014-11-27 | 2020-06-09 | 中兴通讯股份有限公司 | Digital-analog combined anti-aliasing filtering method and device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202068384U (en) * | 2011-05-30 | 2011-12-07 | 桂林电子科技大学 | Short wave frequency range preselection and amplification filter |
| CN203522670U (en) * | 2013-10-18 | 2014-04-02 | 常州国光数据通信有限公司 | Short-wave tracking tuned filter circuit |
| CN207638623U (en) * | 2018-01-11 | 2018-07-20 | 深圳互由科技有限公司 | A kind of tuning filtering device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101931426B (en) * | 2010-04-21 | 2013-05-15 | 北京昆腾微电子有限公司 | Circuit and tuning method for front tunable filter for communication and broadcasting receiver |
| US9608515B2 (en) * | 2015-02-25 | 2017-03-28 | Analog Devices Global | Resonance detection and filtering circuitry |
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2018
- 2018-01-11 CN CN201810027953.5A patent/CN108155885B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202068384U (en) * | 2011-05-30 | 2011-12-07 | 桂林电子科技大学 | Short wave frequency range preselection and amplification filter |
| CN203522670U (en) * | 2013-10-18 | 2014-04-02 | 常州国光数据通信有限公司 | Short-wave tracking tuned filter circuit |
| CN207638623U (en) * | 2018-01-11 | 2018-07-20 | 深圳互由科技有限公司 | A kind of tuning filtering device |
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