CN202259613U - Balanced type RF electrically tunable band-pass filter with constant relative bandwidth - Google Patents
Balanced type RF electrically tunable band-pass filter with constant relative bandwidth Download PDFInfo
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- CN202259613U CN202259613U CN2011201771380U CN201120177138U CN202259613U CN 202259613 U CN202259613 U CN 202259613U CN 2011201771380 U CN2011201771380 U CN 2011201771380U CN 201120177138 U CN201120177138 U CN 201120177138U CN 202259613 U CN202259613 U CN 202259613U
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Abstract
The utility model discloses a balanced type RF (Radio Frequency) electrically tunable band-pass filter with a constant relative bandwidth. The band-pass filter consists of an upper-layer microstrip structure, a middle-layer medium substrate and a lower-layer grounded metal; wherein the upper-layer microstrip structure adopts a balanced circuit and comprises four half-wavelength resonators, two input feed networks, two output feed networks, two input ports and two output ports; the four half-wavelength resonators all consist of microstrip lines and varactors connected at two ends; a middle part of a first half-wavelength resonator is connected with a capacitor and a microstrip line, a middle part of a third half-wavelength resonator is connected with a capacitor; a second half-wavelength resonator and a fourth half-wavelength resonator are bended and symmetrical vertically; and the whole filter has a vertical mirror symmetry structure. The balanced type RF electrically tunable band-pass filter of the utility model can realize the constant relative bandwidth when a centre frequency is tuned, and can suppress common-mode interferences, thus the balanced type RF electrically tunable band-pass filter can be used for a reconfigurable RF front end of wireless communication.
Description
Technical field
The utility model relates to the adjustable balanced type radio frequency electrically adjusted band-pass filter of centre frequency, is specifically related to a kind of balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth that can be applicable in multiband, broadband and the restructural radio-frequency front-end system.
Background technology
Modern ULTRA-WIDEBAND RADAR and radio communication require to adopt high performance restructural radio-frequency front-end.For example in the cognitive radio system, in order to make full use of and to merge various wireless channel and standard, radio-frequency front-end need be operated on the different frequencies, and this just needs the tunable restructural radio-frequency front-end of centre frequency.Radio frequency electrically adjusted band-pass filter is the important component part of restructural radio-frequency front-end, therefore comes into one's own day by day.Aspect this, some research reports have been arranged at present, multiple different tuning device also is used, for example semiconductor variable capacitance diode, radio-frequency micro electromechanical system (RF MEMS) capacitance tube and ferroelectric thin-flim materials varactor etc.
No matter adopt which kind of tuning device, the problem that radio frequency electrically adjusted band-pass filter faced mainly comprises:
(1) for example when the centre frequency of tuning passband; The relative bandwidth of passband also can change thereupon; And the relative bandwidth of wireless channel is invariable in plurality of applications, so we need make the relative bandwidth of passband keep invariable in tuning centre frequency.
(2) interference of system's ambient noise.The existence of ambient noise causes the decreased performance of filter, thereby has influence on the overall performance of radio-frequency front-end.Therefore must take some to suppress the method for ambient noise.
To the constant problem of the tuning Time Bandwidth of centre frequency, certain methods has been proposed at present.According to " M. Sanchez-Renedo, R. Gomez-Garcia, J. I. Alonso, and C. Briso-Rodriguez,
Tunable combline filter with continuous control of center frequency and bandwidth, IEEE Trans. Microw. Theory Tech., vol. 53, no. 1, pp. 191-199, Jan, 2005. " and the analysis that provided can know, control coupling coefficient through between resonator, inserting medium, thereby it is constant to satisfy bandwidth.According to " S. J. Park, and G. M. Rebeiz,
Low-loss two-pole tunable filters with three different predefined bandwidth characteristics, IEEE Trans. Microw. Theory Tech., vol. 56; No. 5, pp. 1137-1148, May; 2008. " analysis that provided can know, adopts independently electric coupling and magnetic coupling mechanism to control the variation of coupling coefficient, can realize specific bandwidth characteristic.According to " M. A. El-Tanani, and G. M. Rebeiz,
High-Performance 1.5-2.5-GHz RF-MEMS Tunable Filters for Wireless Applications, IEEE Trans. Microw. Theory Tech., vol. 58, no. 6, pp. 1629-1637, Jun, 2010. " and the analysis that provided can know that it is constant to adopt electromagnetism hybrid coupled mechanism can satisfy bandwidth equally.Yet the top method that proposes all is the single port circuit, and is powerless basically for the inhibition of ambient noise.
The balanced structure circuit has the better inhibited effect to ambient noise, so is used widely in the balancing circuitry modern communication system.Current most research mainly concentrates on stopband expansion, common mode inhibition, widens passband or uses differential-mode response to obtain double frequency-band.According to " J. Shi, and Q. Xue,
Balanced Bandpass Filters Using Center-Loaded Half-Wavelength Resonators, IEEE Trans. Microw. Theory Tech., vol. 58, no. 4, pp. 970-977, Apr, 2010. " and the analysis that provided can know that the mode of middle loading resistor can absorb common-mode signal.But balanced type Design of Filter recited above all is that frequency is nonadjustable.Up to the present also having no research report is about having the radio frequency electrically adjusted filter of balanced type of relative bandwidth control and common mode inhibition characteristic.
The utility model content
In order to reach constant relative bandwidth; And this type of ambient noise common-mode signal suppressed; The utility model provides a kind of balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth; This balanced type band pass filter Constant relative bandwidth when not only centre frequency is tuning, and common-mode signal had the good restraining effect.
The utility model solves the technical scheme that its technical problem adopted and comprises:
Balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth comprises the microstrip structure on upper strata, the grounded metal of intermediate layer medium substrate and lower floor; The upper strata microstrip structure is attached to intermediate layer dielectric-slab upper surface, and intermediate layer dielectric-slab lower surface is a grounded metal; The upper strata microstrip structure comprises four half-wave resonator, two input feeding networks, two outputs feeding network, two input ports and two output ports; Two input ports are connected with two input feeding networks respectively; Two output ports are connected with two output feeding networks respectively; Two input feeding networks are coupled with first half-wave resonator respectively; First half-wave resonator is coupled with second half-wave resonator and the 4th half-wave resonator respectively again; Second half-wave resonator and the 4th half-wave resonator are coupled with the 3rd half-wave resonator respectively again; The 3rd half-wave resonator is coupled with two output feeding networks respectively again, and the centre of first half-wave resonator and the 3rd half-wave resonator all is loaded with the different big or small electric capacity that are used to absorb common-mode signal, and all there is variable capacitance diode at the two ends of above-mentioned all half-wave resonator.
Said first half-wave resonator is connected and composed by first variable capacitance diode, first microstrip line, second microstrip line, second variable capacitance diode in order; The anode of first variable capacitance diode and second variable capacitance diode all passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal, and the 3rd half-wave resonator is identical with the first half-wave resonator structure; Second half-wave resonator is connected and composed by the 3rd variable capacitance diode, the 3rd microstrip line, the 4th microstrip line, the 5th microstrip line, the 4th variable capacitance diode in order; The anode of the 3rd variable capacitance diode and the 4th variable capacitance diode all passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal; The 4th half-wave resonator is identical with the second half-wave resonator structure and between first half-wave resonator and the 3rd half-wave resonator, the 3rd microstrip line of second half-wave resonator and first microstrip line of first half-wave resonator laterally arrange and constitute the interstage coupling structure; The 5th microstrip line of second half-wave resonator and the 6th microstrip line of the 3rd half-wave resonator laterally arrange and constitute the interstage coupling structure.About above-mentioned four half-wave resonator are arranged into together, equal symmetrical structure up and down; Two first input feeding networks of importing in the feeding network are connected and composed by the 8th microstrip line, the 9th microstrip line, the tenth microstrip line in order; First microstrip line of the tenth microstrip line and first half-wave resonator laterally arranges and constitutes the interstage coupling structure; The tenth microstrip line end passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal, and it is identical that the structure of the second input feeding network and first is imported feeding network; First input end mouth in two input ports is made up of the 7th microstrip line; The 7th microstrip line is connected with the 8th microstrip line top; Second input port is identical with the first input end mouth structure; Two input feeding networks are identical with two output feeding network structures, and two input ports are identical with two output port structures; About two input feeding networks, two outputs feeding networks, two input ports, two output ports and above-mentioned four half-wave resonator are arranged into together, equal symmetrical structure up and down.
The other end of the said electric capacity that loads in the middle of said first half-wave resonator and the 3rd half-wave resonator passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal.Said electric capacity one end that loads in the middle of first half-wave resonator is connected with first half-wave resonator, and the other end is connected with the 11 microstrip line, and the 11 microstrip line other end passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal.
Described balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth; When first input end mouth and second input port input difference mode signal, whole filter forms an electric divider wall on the linear position at the mid point place of first half-wave resonator and the 3rd half-wave resonator.Because the coupling of this structure between resonator mainly is electric coupling; First half-wave resonator and the 3rd half-wave resonator do not have electric current in the centre position, are connected on middle said electric capacity that loads of first half-wave resonator and the 3rd half-wave resonator and the 11 microstrip line to ignore.So under the differential mode excitation, first half-wave resonator is two identical quarter-wave resonators with the 3rd half-wave resonator equivalence, while and the coupling of second half-wave resonator form bandpass filter structures; When first input end mouth and second input port input common-mode signal, whole filter forms a magnetic divider wall on the linear position at the mid point place of first half-wave resonator and the 3rd half-wave resonator.First half-wave resonator and the 3rd half-wave resonator are equipped with current flowing in interposition, and being connected on middle said electric capacity that loads of first half-wave resonator and the 3rd half-wave resonator and the 11 microstrip line has current flowing.Said electric capacity and the 11 microstrip line that two quarter-wave resonators of first half-wave resonator and the equivalence of the 3rd half-wave resonator load in the middle of need considering.Because the said electric capacity that loads in the middle of on first half-wave resonator and the 3rd half-wave resonator is different, the resonance frequency of two quarter-wave resonance devices of real work equivalence is different, makes common-mode signal not pass through, and reaches the effect of inhibition.
For further realizing the utility model purpose, the said first microstrip line length with balanced type radio frequency electrically adjusted band-pass filter of constant relative bandwidth is 7.6mm, and width is 0.6mm; The 3rd microstrip line length is 5.2mm, and width is 0.6mm; The 4th microstrip line length is 5.6mm, and the 8th microstrip line length is 9.2mm, and width is 0.8mm; The 9th microstrip line length is 4mm, and width is 1.2mm, and the tenth microstrip line length is 4.9mm; Width is 0.3mm, and the 11 microstrip line length is 1.8mm, and width is 0.5mm; The said capacitance size that loads in the middle of first half-wave resonator is 47pF; The said capacitance size that loads in the middle of the 3rd half-wave resonator is 3pF, and the distance between first microstrip line and the tenth microstrip line is 0.15mm, and the distance between first microstrip line and the 3rd microstrip line is 0.65mm.
Compared with prior art, the utility model adopts novel balanced structure and half-wave resonator interstage coupling structure, and the relative bandwidth bandwidth kept electrically adjusted band-pass filter constant and ability good restraining common mode interference signal when centre frequency was tuning.Have following advantage and effect generally:
(1) owing to use the balanced structure design, this band pass filter then has good inhibitory effect for difference mode signal ability operate as normal for common-mode signal, and therefore interference has immunologic function for this type of ambient noise.The common mode inhibition level of surveying among the embodiment all surpasses-23dB.
(2) through setting to input feeding network and interstage coupling mode, can be implemented in centre frequency relative bandwidth constant when tuning, can satisfy the different application demand.
Description of drawings
Fig. 1 is the schematic diagram with balanced type radio frequency electrically adjusted band-pass filter FBW of constant relative bandwidth;
Fig. 2 is a FBW differential mode equivalent electric circuit;
Fig. 3 a is the equivalent quarter-wave resonance device under the FBW differential mode situation;
Fig. 3 b is the equivalent half-wave resonator under the FBW differential mode situation;
Fig. 4 is the relation that the quarter-wave resonance device is thanked vibration frequency, capacitance and microstrip line length among Fig. 3 a;
Fig. 5 is the relation that half-wave resonator is thanked vibration frequency, capacitance and microstrip line length among Fig. 3 b;
Fig. 6 is the FBW common mode equivalent circuit;
Fig. 7 a is the equivalent quarter-wave resonance device of first resonator under the FBW common mode situation;
Fig. 7 b is the equivalent quarter-wave resonance device of the 3rd resonator under the FBW common mode situation;
Fig. 8 a is the differential mode transfer curve of FBW;
Fig. 8 b is the differential mode return loss plot of FBW;
Fig. 8 c is the local sectional drawing of the differential mode transfer curve of FBW;
Fig. 8 d is the common mode transmission characteristic curve that FBW singly connects microstrip line;
Fig. 8 e is the common mode transmission characteristic curve that FBW singly connects electric capacity;
Fig. 8 f is the common mode transmission characteristic curve that FBW connects microstrip line and electric capacity.
Specific embodiments
Below in conjunction with accompanying drawing the utility model is done further detailed explanation, but the utility model requires the scope of protection to be not limited to down the scope of example statement.
As shown in Figure 1, the balanced type radio frequency electrically adjusted band-pass filter FBW with constant relative bandwidth comprises the microstrip structure on upper strata, the grounded metal of intermediate layer medium substrate and lower floor; The upper strata microstrip structure is attached to intermediate layer dielectric-slab upper surface, and intermediate layer dielectric-slab lower surface is a grounded metal; The upper strata microstrip structure comprises four half-wave resonator, two input feeding networks, two outputs feeding network, two input ports and two output ports; Two input ports are connected with two input feeding networks respectively; Two output ports are connected with two output feeding networks respectively; Two input feeding networks are coupled with first half-wave resonator respectively; First half-wave resonator is coupled with second half-wave resonator and the 4th half-wave resonator respectively again; Second half-wave resonator and the 4th half-wave resonator are coupled with the 3rd half-wave resonator respectively again; The 3rd half-wave resonator is coupled with two output feeding networks respectively again, and the centre of first half-wave resonator and the 3rd half-wave resonator all is loaded with the different big or small electric capacity that are used to absorb common-mode signal, and all there is variable capacitance diode at the two ends of above-mentioned all half-wave resonator.
Said first half-wave resonator is connected and composed by first variable capacitance diode 5, first microstrip line 6, second microstrip line 7, second variable capacitance diode 8 in order; The anode of first variable capacitance diode 5 and second variable capacitance diode 8 all passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal, and the 3rd half-wave resonator is identical with the first half-wave resonator structure; Second half-wave resonator is connected and composed by the 3rd variable capacitance diode 11, the 3rd microstrip line 12, the 4th microstrip line 13, the 5th microstrip line 14, the 4th variable capacitance diode 15 in order; The anode of the 3rd variable capacitance diode 11 and the 4th variable capacitance diode 15 all passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal; The 4th half-wave resonator is identical with the second half-wave resonator structure and between first half-wave resonator and the 3rd half-wave resonator, the 3rd microstrip line 12 of second half-wave resonator and first microstrip line 6 of first half-wave resonator laterally arrange and constitute the interstage coupling structure; The 5th microstrip line 14 of second half-wave resonator and the 6th microstrip line 16 of the 3rd half-wave resonator laterally arrange and constitute the interstage coupling structure.About above-mentioned four half-wave resonator are arranged into, equal symmetrical structure up and down; Two inputs first in feeding network input feeding network 18 is connected and composed by the 8th microstrip line 2, the 9th microstrip line 3, the tenth microstrip line 4 in order; First microstrip line 6 of the tenth microstrip line 4 and first half-wave resonator laterally arranges and constitutes the interstage coupling structure; The tenth microstrip line 4 ends pass the intermediate layer medium substrate and link to each other with the lower floor grounded metal, and it is identical that the structure of the second input feeding network 19 and first is imported feeding network 18; First input end mouth IN in two input ports is made up of the 7th microstrip line 1; The 7th microstrip line 1 is connected with the 8th microstrip line 2 tops; The second input port IN ' is identical with first input end mouth IN structure; Two output feeding networks are identical with two input feeding network structures, and two output ports are identical with two input port structures; About two input feeding networks, two outputs feeding networks, two input ports, two output ports and above-mentioned four half-wave resonator are arranged into together, equal symmetrical structure up and down.
Said first electric capacity 9 that loads in the middle of first half-wave resonator and the 3rd half-wave resonator and second electric capacity 17 all have an end to pass the intermediate layer medium substrate to link to each other with the lower floor grounded metal.Said first electric capacity, 9 one ends that load in the middle of first half-wave resonator are connected with first half-wave resonator, and the other end is connected with the 11 microstrip line 10, the 11 microstrip line 10 other ends and passes the intermediate layer medium substrate and link to each other with the lower floor grounded metal.
The characteristic impedance of the transmission line of two input ports and two output ports all is 50 Ω.
The parameters of adjustment filter makes filter on total, reach balance.When first input end mouth IN and the second input port IN ' input difference mode signal, whole filter forms an electric divider wall on the linear position at the mid point place of first half-wave resonator and the 3rd half-wave resonator.Because this structure interstage coupling mainly is electric coupling; First half-wave resonator and the 3rd half-wave resonator do not have electric current in the centre position, and being connected on said first electric capacity 9, second electric capacity 17 and the 11 microstrip line 10 that load in the middle of first half-wave resonator and the 3rd half-wave resonator can ignore.Therefore under differential mode excitation situation, the filter construction equivalence is a bandpass filter structures shown in Figure 2.At this moment, first half-wave resonator and the 3rd half-wave resonator all equivalence are identical quarter-wave resonance device, and second half-wave resonator is constant.Fig. 3 a and 3b have provided the quarter-wave resonance device and second half-wave resonator of equivalence under the differential mode situation.According to " A. R. Brown, and G. M. Rebeiz,
A varactor-tuned RF filter, IEEE Trans. Microw. Theory Tech., vol. 48, and no. 7; Pp. 1157-1160, Jul, 2000. " analysis that provided can know; in Fig. 3 a, when quarter-wave resonance device resonance, see admittance Y in the past from quarter-wave resonance device left end
Dd_in1Imaginary part equal zero, for a given voltage, load the resonance frequency of the whole resonator of variable capacitance diode:
，
Wherein
is the characteristic admittance of resonator;
is the electrical length of first microstrip line 6; C is the capacitance that variable capacitance diode is depressed in different electric; In Fig. 4, shown the resonance frequency of quarter-wave resonance device among Fig. 3 a, the capacitance C of variable capacitance diode and the relation of microstrip line length, can find out the increase along with electric capacity, the resonance frequency of resonator descends; Along with shortening of microstrip line length, scalable is interval to become big; For second half-wave resonator, resonance frequency is equally:
;
Wherein
is the characteristic admittance of resonator;
is the electrical length of half-wave resonator; C is the capacitance that variable capacitance diode is depressed in different electric; The resonance frequency of second half-wave resonator among Fig. 3 b, the capacitance C of variable capacitance diode and the relation of microstrip line length in Fig. 5, have been shown; Can find out at the relation property of length 10-18mm scope interior resonance frequency and capacitance similar with the relation property of quarter-wave resonance device in length 6-8mm; During as
, under the identical voltage
; So two resonant frequencies can mate when voltage is identical, filter can operate as normal.
When first input end mouth IN and the second input port IN ' input common-mode signal, whole filter forms a magnetic divider wall on the linear position at the mid point place of first half-wave resonator and the 3rd half-wave resonator.First half-wave resonator and the 3rd half-wave resonator are equipped with current flowing in interposition, and being connected on middle said first electric capacity 9 that loads of first half-wave resonator and the 3rd half-wave resonator and second electric capacity 17 and the 11 microstrip line 10 has current flowing.Said electric capacity and the 11 microstrip line that two quarter-wave resonators of first half-wave resonator and the equivalence of the 3rd half-wave resonator load in the middle of need considering.Equivalent electric circuit under the common mode situation is as shown in Figure 6, can see that two quarter-wave resonance devices of equivalence structurally are different; Fig. 7 a and 7b two the equivalent quarter-wave resonance devices that drawn; For the quarter-wave resonance device of Fig. 7 a, resonance frequency is:
;
Shown in figure, Y
1And Y
3It is the characteristic admittance of microstrip line; θ
1And θ
3It is the electrical length of microstrip line; C is the capacitance that variable capacitance diode is depressed in different electric.
For the quarter-wave resonance device of Fig. 7 b, resonance frequency is:
Shown in figure, Y
1It is the characteristic admittance of microstrip line; θ
1The electrical length of microstrip line; C is the capacitance that variable capacitance diode is depressed in different electric; C
2It is the capacitance of said loading capacitance.
Contrast
and
can be found out; Because load the 11 microstrip line 10, first electric capacity 9 is different with second electric capacity 17; Make that the resonance frequency of these two resonators is different, signal can not pass through; Common-mode signal just has been suppressed.
Below among the embodiment, the FBW with 9.5% constant relative bandwidth is produced on that relative dielectric constant is 10.2, thickness is that 0.63mm, fissipation factor are on 0.0023 the medium substrate.Variable capacitance diode is selected the silicon variable capacitance diode lsv277 of Toshiba for use.
Embodiment: 1.17GHz-1.95GHz has the balanced type radio frequency electrically adjusted band-pass filter of 9.5% constant relative bandwidth
1.17GHz-1.95GHz it is as shown in Figure 1 to have the balanced type radio frequency electrically adjusted band-pass filter structure of 9.5% constant relative bandwidth.Concrete parameter is: first microstrip line, 6 length are 7.6mm, and width is 0.6mm, and the 3rd microstrip line 12 length are 5.2mm, and width is 0.6mm; The 4th microstrip line 13 length are 5.6mm, and the 8th microstrip line 2 length are 9.2mm, and width is 0.8mm, and the 9th microstrip line 3 length are 4mm; Width is 1.2mm, and the tenth microstrip line 4 length are 4.9mm, and width is 0.3mm; The 11 microstrip line 10 length are 1.8mm, and width is 0.5mm, and first electric capacity 9 is 47pF; Second electric capacity 17 is 3pF, and the distance between first microstrip line 6 and the tenth microstrip line 4 is 0.15mm, and the distance between first microstrip line 6 and the 3rd microstrip line 12 is 0.65mm.Fig. 8 has provided the result that the filter that utilizes above-mentioned parameter to design carries out emulation and actual measurement, and wherein emulation and actual measurement are to use the commercial electromagnetism ADS of simulation software and the E5071C network analyzer of Agilent company to accomplish respectively.Fig. 8 a is the transmission characteristic of emulation, calculating and the test when four special bias voltages under this filter differential mode working condition, and transverse axis is represented frequency, and the longitudinal axis is represented transmission characteristic | S
Dd21|.Fig. 8 b is depicted as the reflection characteristic of this filter, and transverse axis is represented frequency, and the longitudinal axis is represented return loss | S
Dd11|.Visible by Fig. 8 a and Fig. 8 b, the band connection frequency of filter can be transferred to 1.95GHz from 1.17GHz, has 51.8% relative adjustment scope.To all tuning states, the in-band insertion loss of measurement is between 2.9-6dB, and return loss all is lower than-10dB.Fig. 8 c is that the intercepting of transmission characteristic is amplified; It is thus clear that in the band relative bandwidth of each passband be 9.6
0.35%, substantially constant.Shown in Fig. 8 d be under the common mode working condition; When the variable capacitance diode bias voltage is 3V and 8V; In the middle of first half-wave resonator, only connect the 11 microstrip line 10, length L 7 is respectively 0mm, 1.8mm and 2.8mm, the transmission characteristic when not connecing first electric capacity 9; Can find out connect microstrip line after, near the inhibition to common-mode noise passband 1.9GHz can improve 15dB.Shown in Fig. 8 e be when the variable capacitance diode bias voltage is 3V and 8V; In the middle of first half-wave resonator, only connect first electric capacity 9; Do not connect the 11 microstrip line 10, capacitance C2 is respectively 0pF, 3pF and 5pF, and near the inhibition to common-mode noise second harmonic 3.8GHz can improve 8dB.Therefore can use electric capacity and microstrip line to reach in the frequency band of a broad simultaneously suppresses common-mode noise.Fig. 8 f has shown in the 0.2-4.8GHz common mode inhibition and has been lower than-23dB.
The utility model is based on the balanced structure of mirror image symmetry, under differential mode and common-mode signal, has different equivalent electric circuits, has constant relative bandwidth, and intermediate frequency is adjustable, in the frequency band of broad, suppresses common-mode noise.Bandwidth and passband waveform keep invariable in frequency tuning range.Through the parameter of adjusted design, can regulate bandwidth, promptly this structure can be used for realizing various bandwidth specifications.
The above is merely the preferred embodiments of the utility model, and is in order to restriction the utility model, not all within the spirit and principle of the utility model, any modification of being done, is equal to replacement, improvement etc., all should be included within the protection range of the utility model.
Claims (7)
1. the balanced type radio frequency electrically adjusted band-pass filter that has constant relative bandwidth is characterized in that comprising the microstrip structure on upper strata, the grounded metal of intermediate layer medium substrate and lower floor; The upper strata microstrip structure is attached to intermediate layer dielectric-slab upper surface, and intermediate layer dielectric-slab lower surface is a grounded metal; The upper strata microstrip structure comprises four half-wave resonator, two input feeding networks, two outputs feeding network, two input ports and two output ports; Two input ports are connected with two input feeding networks respectively; Two output ports are connected with two output feeding networks respectively; Two input feeding networks are coupled with first half-wave resonator respectively; First half-wave resonator is coupled with second half-wave resonator and the 4th half-wave resonator respectively again; Second half-wave resonator and the 4th half-wave resonator are coupled with the 3rd half-wave resonator respectively again; The 3rd half-wave resonator is coupled with two output feeding networks respectively again, and the centre of first half-wave resonator and the 3rd half-wave resonator all is loaded with the different big or small electric capacity that are used to absorb common-mode signal, and all there is variable capacitance diode at the two ends of above-mentioned all half-wave resonator.
2. the balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth according to claim 1; It is characterized in that said first half-wave resonator is connected and composed by first variable capacitance diode, first microstrip line, second microstrip line, second variable capacitance diode in order; The anode of first variable capacitance diode and second variable capacitance diode all passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal, and the 3rd half-wave resonator is identical with the first half-wave resonator structure; Second half-wave resonator is connected and composed by the 3rd variable capacitance diode, the 3rd microstrip line, the 4th microstrip line, the 5th microstrip line, the 4th variable capacitance diode in order; The anode of the 3rd variable capacitance diode and the 4th variable capacitance diode all passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal; The 4th half-wave resonator is identical with the second half-wave resonator structure and between first half-wave resonator and the 3rd half-wave resonator, about above-mentioned four half-wave resonator are arranged into together, equal symmetrical structure up and down; Two first input feeding networks of importing in the feeding network are connected and composed by the 8th microstrip line, the 9th microstrip line, the tenth microstrip line in order; First microstrip line of the tenth microstrip line and first half-wave resonator laterally arranges and constitutes the interstage coupling structure; The tenth microstrip line end passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal, and it is identical that the structure of the second input feeding network and first is imported feeding network; First input end mouth in two input ports is made up of the 7th microstrip line; The 7th microstrip line is connected with the 8th microstrip line top; Second input port is identical with the first input end mouth structure; Two input feeding networks are identical with two output feeding network structures, and two input ports are identical with two output port structures; About two input feeding networks, two outputs feeding networks, two input ports, two output ports and above-mentioned four half-wave resonator are arranged into together, equal symmetrical structure up and down.
3. the balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth according to claim 2, it is characterized in that first half-wave resonator and the 3rd half-wave resonator in the middle of the other end of the said electric capacity that loads pass the intermediate layer medium substrate and link to each other with the lower floor grounded metal.
4. the balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth according to claim 2; It is characterized in that said electric capacity one end that loads in the middle of first half-wave resonator is connected with first half-wave resonator; The other end is connected with the 11 microstrip line, and the 11 microstrip line other end passes the intermediate layer medium substrate and links to each other with the lower floor grounded metal.
5. the balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth according to claim 2, first microstrip line that it is characterized in that the 3rd microstrip line and first half-wave resonator of second half-wave resonator laterally arranges and constitutes the interstage coupling structure; The 5th microstrip line of second half-wave resonator and the 6th microstrip line of the 3rd half-wave resonator laterally arrange and constitute the interstage coupling structure.
6. the balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth according to claim 2, the characteristic impedance that it is characterized in that the transmission line of two input ports and two output ports all is 50 Ω.
7. according to each described balanced type radio frequency electrically adjusted band-pass filter with constant relative bandwidth of claim 2～6, it is characterized in that the said first microstrip line length is 7.6mm, width is 0.6mm; The 3rd microstrip line length is 5.2mm, and width is 0.6mm; The 4th microstrip line length is 5.6mm, and the 8th microstrip line length is 9.2mm, and width is 0.8mm; The 9th microstrip line length is 4mm, and width is 1.2mm, and the tenth microstrip line length is 4.9mm; Width is 0.3mm, and the 11 microstrip line length is 1.8mm, and width is 0.5mm; The said capacitance size that loads in the middle of first half-wave resonator is 47pF; The said capacitance size that loads in the middle of the 3rd half-wave resonator is 3pF, and the distance between first microstrip line and the tenth microstrip line is 0.15mm, and the distance between first microstrip line and the 3rd microstrip line is 0.65mm.
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| CN2011201771380U CN202259613U (en) | 2011-05-27 | 2011-05-27 | Balanced type RF electrically tunable band-pass filter with constant relative bandwidth |
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| CN2011201771380U CN202259613U (en) | 2011-05-27 | 2011-05-27 | Balanced type RF electrically tunable band-pass filter with constant relative bandwidth |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102280678A (en) * | 2011-05-27 | 2011-12-14 | 华南理工大学 | Balanced radio frequency electrically tunable bandpass filter with constant relative bandwidth |
| CN103700917A (en) * | 2013-12-20 | 2014-04-02 | 华南理工大学 | Gysel power distribution filter with high power distribution ratio |
| CN105720335A (en) * | 2016-03-24 | 2016-06-29 | 华南理工大学 | Compact electrically tunable balanced band pass filter |
-
2011
- 2011-05-27 CN CN2011201771380U patent/CN202259613U/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102280678A (en) * | 2011-05-27 | 2011-12-14 | 华南理工大学 | Balanced radio frequency electrically tunable bandpass filter with constant relative bandwidth |
| CN102280678B (en) * | 2011-05-27 | 2014-04-02 | 华南理工大学 | Balanced radio frequency electrically tunable bandpass filter with constant relative bandwidth |
| CN103700917A (en) * | 2013-12-20 | 2014-04-02 | 华南理工大学 | Gysel power distribution filter with high power distribution ratio |
| CN103700917B (en) * | 2013-12-20 | 2015-12-02 | 华南理工大学 | There is the Gysel merit filter-divider of high merit proportion by subtraction |
| CN105720335A (en) * | 2016-03-24 | 2016-06-29 | 华南理工大学 | Compact electrically tunable balanced band pass filter |
| CN105720335B (en) * | 2016-03-24 | 2018-07-20 | 华南理工大学 | A kind of compact can the balance bandpass filter adjusted of electricity |
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