CN101262209A - Alterable band-pass filter - Google Patents
Alterable band-pass filter Download PDFInfo
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- CN101262209A CN101262209A CNA200810082192XA CN200810082192A CN101262209A CN 101262209 A CN101262209 A CN 101262209A CN A200810082192X A CNA200810082192X A CN A200810082192XA CN 200810082192 A CN200810082192 A CN 200810082192A CN 101262209 A CN101262209 A CN 101262209A
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Abstract
The invention provides a variable band-pass filter which can realize minitype by reducing a switchable band-pass or component amount of a high-frequency filter of a stop band. In the variable band-pass filter, a first to a third capacitors (C1), (C2) and (C3) are linked in series between an import terminal (1) and an output terminal (2), a first inductor (L1) and a fourth capacitor (C4) are linked in series between a linking point and an earthing point of the first and second capacitors (C1), (C2), a first diode (D1) is linked between the fourth capacitor (C4) and the first inductor (L1). A second inductor (L2) and a fifth capacitor (C5) are linked in series between a linking point and an earthing point of the second and third capacitors (C2), (C3), a second diode (D2) is linked between the fifth capacitor (C5) and the second inductor (L2). A third inductor (L3) is linked between one end of the first and second inductors (L1), (L2), and an earthing end, an eighth capacitor (C8) and a third diode (D3) link with the third inductor (L3) in parallel.
Description
Technical field
The present invention relates to the alterable band-pass filter of changeable passband or stopband.
Background technology
Always the Filter Structures that opens and closes at least one side with regard to existing employing to be arranged in parallel a plurality of filters is switched the filter (for example, with reference to patent documentation 1) of passband (perhaps stopband).High frequency filter shown in Figure 8 is arranged in parallel high frequency high pass filter (perhaps high freguency bandpass filter) 103 and high frequency low pass filter 104, and connect the input part of high frequency high pass filter 103 and the input part of high frequency low pass filter 104 is used as input terminal 101, connect the lead-out terminal of high frequency high pass filter 103 and the efferent of high frequency low pass filter 104 and be used as lead-out terminal 102.And, for the passband that makes high frequency high pass filter 103 becomes stopband, on the leading portion of high frequency high pass filter 103, be provided with switching circuit 105.
But, be arranged in parallel a plurality of filters and opening and closing by switch in the structure of at least one side, be difficult to realize the problem of miniaturization with regard to existing the parts number of packages to increase.
Summary of the invention
The present invention be directed to the problems referred to above and propose, its purpose is to provide a kind of both available few parts number of packages to switch passband or stopband, realizes the alterable band-pass filter of miniaturization again easily.
Alterable band-pass filter of the present invention is characterised in that to possess: the 1st capacitor, and an end is connected with input terminal; The 2nd capacitor, an end is connected with the other end of above-mentioned the 1st capacitor; The 3rd capacitor is connected between the other end and lead-out terminal of above-mentioned the 2nd capacitor; The 1st inductance, an end is connected with tie point between above-mentioned the 1st capacitor and above-mentioned the 2nd capacitor; The 4th capacitor is connected between above-mentioned the 1st inductance and the ground connection; The 1st switch makes above-mentioned the 4th capacitor be connected with an end of above-mentioned the 1st inductance or disconnects; The 2nd inductance, an end is connected with tie point between above-mentioned the 2nd capacitor and above-mentioned the 3rd capacitor; The 5th capacitor is connected between above-mentioned the 2nd inductance and the ground connection; The 2nd switch makes above-mentioned the 5th capacitor be connected with an end of above-mentioned the 2nd inductance or disconnects; The 3rd inductance is connected between the other end and ground connection of the other end of above-mentioned the 1st inductance and above-mentioned the 2nd inductance; And the 3rd switch, be connected in parallel and the two ends of above-mentioned the 3rd inductance of high frequency short circuit with above-mentioned the 3rd inductance, and, disconnect above-mentioned the 3rd switch when connecting the above-mentioned the 1st and the 2nd switch and form band pass filter, connect above-mentioned the 3rd switch when disconnecting the above-mentioned the 1st and the 2nd switch and form the high pass filter that passband is higher than above-mentioned band pass filter.
According to said structure, available simple structure realization can be selected the high frequency filter of the VHF broadcast band and the UHF broadcast band of TV tuner.For example, can be by being 3 diodes of the 1st to the 3rd switch, when selecting the VHF broadcast band, switch to the logical mode filter of band of decay FM frequency band and UHF broadcast band, and when selecting the UHF broadcast band, switch to the high-pass type filter of FM frequency band and VHF broadcast band of decaying, thereby can reduce the parts number of packages.
And, above-mentioned alterable band-pass filter of the present invention is characterised in that, possess the 6th capacitor and the 7th capacitor, the 6th capacitor is connected between the end of tie point between the above-mentioned the 1st and the 2nd capacitor and above-mentioned the 1st inductance, and the 7th capacitor is connected between the end of tie point between the above-mentioned the 2nd and the 3rd capacitor and above-mentioned the 2nd inductance, and, when connecting the above-mentioned the 1st and the 2nd switch, disconnect above-mentioned the 3rd switch and when having formed band pass filter, just forming pad electrode is in than the trap circuit on the low frequency of the passband of this band pass filter, and connect above-mentioned the 3rd switch when disconnecting the above-mentioned the 1st and the 2nd switch and when having formed passband and being higher than the high pass filter of above-mentioned band pass filter, just form pad electrode and be in than the trap circuit on the low frequency of the passband of this high pass filter.
According to said structure, disconnect the 3rd switch when connecting the 1st and the 2nd switch and when having formed the band pass filter of VHF broadcast band, for example, just can be at the circuit of FM radio broadcasting frequency band series resonance except the 1st and the 3rd capacitor, and can on FM radio broadcasting frequency band, form trap.And, connect the 3rd switch when disconnecting the 1st and the 2nd switch and when having formed the high pass filter of UHF broadcast band, for example, just can on the 330MHz of the 322MHz of specific low-power wireless machine, analog cordless telephone machine tool, form trap.
And, above-mentioned alterable band-pass filter of the present invention, it is characterized in that, the the 1st and the 2nd switching diode that is constituted by a diode constitutes the above-mentioned the 1st and the 2nd switch respectively, and, the anode of above-mentioned the 1st switching diode is connected with above-mentioned the 4th capacitor and its negative electrode is connected with an end of above-mentioned the 1st inductance, the anode of above-mentioned the 2nd switching diode is connected with above-mentioned the 5th capacitor and its negative electrode is connected with an end of above-mentioned the 2nd inductance, and control voltage be applied to the above-mentioned the 1st and the anode of the 2nd switching diode on.
According to said structure, 1st, the control voltage of the 2nd switching diode is by flowing to ground connection after the 1st (the 2nd) inductance and the 3rd inductance, because of the 4th (the 5th) capacitor, 1st, the anode of the 2nd switching diode does not join with ground connection on direct current, therefore, the direct current that does not need to control the 1st, the 2nd switching diode blocks capacitor or chokes (interchange is blocked) inductance, thereby can cut down the parts number of packages and realize miniaturization.
And, above-mentioned alterable band-pass filter of the present invention is characterised in that, constitute above-mentioned the 3rd switch by the 3rd switching diode and the 8th capacitor, the 3rd switching diode is constituted by a diode, direct current blocks and the one end is connected with the anode of the 3rd switching diode and the 8th capacitor is used for, and, the negative electrode of above-mentioned the 3rd switching diode is connected with tie point between above-mentioned the 1st, the 2nd, the 3rd inductance, and an end of above-mentioned the 8th capacitor is connected with ground connection, and control voltage is applied on the anode of above-mentioned the 3rd switching diode.
According to said structure, when disconnecting the 3rd switching diode, the control circuit of controlling the anode of the 3rd switching diode and switching band pass filter and high pass filter just breaks away from this alterable band-pass filter, and when connecting the 3rd switching diode, therefore the anode of the 3rd switching diode can prevent that this alterable band-pass filter is controlled the influence of circuit with regard to high frequency earthing.
And above-mentioned alterable band-pass filter of the present invention is characterised in that, when having disconnected above-mentioned the 3rd switch when connecting the above-mentioned the 1st and the 2nd switch, its passband is the VHF broadcast band; And when connecting above-mentioned the 3rd switch when disconnecting the above-mentioned the 1st and the 2nd switch, its passband is more than or equal to uhf band.
According to said structure, because of having disturbing wave (electric wave of FM radio wave and UHF broadcast band) on the high frequency side of VHF broadcast band and the lower frequency side, so can make it to become the band pass filter of the VHF broadcast band disturbing wave of decaying.And the UHF broadcast band exists disturbing wave (electric wave of VHF broadcast band) and frequency band also very wide on its lower frequency side, so can make it to become more than or equal to the high pass filter of the UHF broadcast band disturbing wave of decaying.
According to the present invention, the parts number of packages of the high frequency filter by cutting down changeable passband or stopband is realized miniaturization.
Description of drawings
Fig. 1 is the circuit structure diagram of the involved alterable band-pass filter of one embodiment of the present invention.
(a) of Fig. 2 is the circuit structure diagram when selecting low-frequency range with the alterable band-pass filter of Fig. 1, the equivalent circuit figure during (b) for the selection low-frequency range.
Fig. 3 is frequency characteristic figure that simulate at the equivalent circuit of Fig. 2 (b), when selecting low-frequency range.
(a) of Fig. 4 is the circuit structure diagram when selecting high band with the alterable band-pass filter of Fig. 1, the equivalent circuit figure during (b) for the selection high band.
Fig. 5 is frequency characteristic figure that simulate at the equivalent circuit of Fig. 4 (b), when selecting high band.
Fig. 6 is the circuit structure diagram of the variation of the involved alterable band-pass filter of above-mentioned a kind of execution mode.
(a) of Fig. 7 is the frequency characteristic figure when selecting low-frequency range with the alterable band-pass filter of Fig. 6, (b) is the frequency characteristic figure when selecting high band with the alterable band-pass filter of Fig. 6.
Fig. 8 is the skeleton diagram of high frequency filter in the past.
Description of reference numerals:
1 input terminal, 2 lead-out terminals, C1～C8 the 1st to the 8th capacitor, D1～D3 the 1st be to the 3PIN diode, L1, L2 the 1st, the 2nd inductance, 3 commutation circuits, 4 power supplys.
Embodiment
Describe a kind of execution mode when on the high frequency filter of the TV tuner that can select VHF broadcast band and UHF broadcast band, being suitable for alterable band-pass filter of the present invention below with reference to accompanying drawings in detail.
Fig. 1 is the circuit structure diagram of the involved alterable band-pass filter of present embodiment.At the alterable band-pass filter shown in this figure, high-frequency signal is incorporated into input terminal 1 by antenna side, and lead-out terminal 2 outputs are by the high-frequency signal of the frequency band of wanting of this filter extraction.1st, the 2nd, the 3rd capacitor C1, C2, C3 are connected in series between this input terminal 1 and the lead-out terminal 2.Tie point between the 1st capacitor C1 and the 2nd capacitor C2 is connected with an end of the 1st inductance L 1.The 4th capacitor C4 is connected between the end and ground connection of the 1st inductance L 1, and 1PIN diode D1 is connected between the end of the 4th capacitor C4 and the 1st inductance L 1.And the 5th capacitor C5 is connected between the end and ground connection of the 2nd inductance L 2, and 2PIN diode D2 is connected between the end of the 5th capacitor C5 and the 2nd inductance L 2.
In present embodiment, the 6th capacitor C6 is connected between the end of tie point between the 1st capacitor C1 and the 2nd capacitor C2 and the 1st inductance L 1, and the 7th capacitor C7 is connected between the end of tie point between the 2nd capacitor C2 and the 3rd capacitor C3 and the 2nd inductance L 2.
And the other end of the 1st and the 2nd inductance L 1, L2 is connected with an end of the 3rd inductance L 3, and the other end of the 3rd inductance L 3 is connected with ground connection.The 3rd inductance L 3 is connected in parallel with being used for the 8th capacitor C8 that direct current blocks, and 3PIN diode D3 is connected between the end of the 8th capacitor C8 and the 3rd inductance L 3.
And, also possess the commutation circuit 3 of switching high band (UHF broadcast band) and low-frequency range (VHF broadcast band).The stiff end of commutation circuit 3 is connected with power supply 4, and wherein the switched terminal 3a of a side is connected with the anode of 3PIN diode D3, and the switched terminal 3b of opposite side is connected with the 1st and the anode of 2PIN diode D1, D2.In commutation circuit 3, on switched terminal 3a, be connected and fixed end and just can select high band, on switched terminal 3b, be connected and fixed end and just can select low-frequency range.
Below, explanation is had the action of alterable band-pass filter said structure, that present embodiment is involved and the filter characteristic that will set.
At first, the switched terminal 3b of explanation commutation circuit 3 is connected and fixed end and situation when having selected low-frequency range (VHF broadcast band).When low-frequency range is selected in Fig. 2 (a) expression the 1st, the 2nd, the open and-shut mode of 3PIN diode D1, D2, D3.Voltage by commutation circuit 3 be applied to the 1st and the anode of 2PIN diode D1, D2 on, connect the 1st and 2PIN diode D1, D2.So the end of the 1st, the 2nd inductance L 1, L2 is connected with ground connection by the 4th, the 5th capacitor C4, C5.And, because becoming zero V, the anode of 3PIN diode D3 disconnects, so the 8th capacitor C8 will not be connected in parallel with the 3rd inductance L 3.
Fig. 2 (b) for the 1st, the 2nd, 3PIN diode D1, the equivalent circuit figure of its state when D2, D3 set for shown in Fig. 2 (a).Constitute the LC resonant circuit by the 1st inductance L 1 and the 3rd inductance L the 3, the 6th capacitor C6 and the 4th capacitor C4, and constitute the LC resonant circuit by the 2nd inductance L 2 and the 3rd inductance L the 3, the 7th capacitor C7 and the 5th capacitor C5.And two resonant circuits carry out the combination of M type in the 3rd inductance L 3, and constitute the double-tuned circuit with trap.
Its frequency characteristic figure when Fig. 3 has carried out simulation for set the numerical value shown in Fig. 2 (b) on each structural element that constitutes double-tuned circuit.As shown in the drawing, the attenuation degree of VHF broadcast band is very little, and about the neighboring region of the lower frequency side of VHF broadcast band decay 30dB, and the neighboring region of VHF broadcast band high frequency side is decayed about 10dB on the other hand, thereby can think that having obtained with the VHF broadcast band is the pass band filter characteristic of passband.And, form trap at the FM frequency band, and the FM frequency band that becomes disturbing wave of the TV tuner that can decay fully.
Secondly, the switched terminal 3a of explanation commutation circuit 3 is connected and fixed end and situation when having selected high band (UHF broadcast band).When high band is selected in Fig. 4 (a) expression the 1st, the 2nd, the open and-shut mode of 3PIN diode D1, D2, D3.Voltage is applied on the anode of 3PIN diode D3 by commutation circuit 3, connects 3PIN diode D3.So the 8th capacitor C8 and the 3rd inductance L 3 are connected in parallel.And, because the 1st, the anode of 2PIN diode D1, D2 becomes zero V and disconnects, so the 4th, the 5th capacitor C4, C5 are not connected in parallel with the 1st, the 2nd inductance L 1, L2.
Fig. 4 (b) for the 1st, the 2nd, 3PIN diode D1, the equivalent circuit figure of its state when D2, D3 set for shown in Fig. 4 (a).Tie point between the 1st capacitor C1 and the 2nd capacitor C2 will be connected with ground connection by the 6th capacitor C6 and the 1st inductance L 1, and the tie point between the 2nd capacitor C2 and the 3rd capacitor C3 will be connected with ground connection by the 7th capacitor C7 and the 2nd inductance L 2, thus its whole π type high pass filter that forms.
Its frequency characteristic figure when Fig. 5 has carried out simulation for set the numerical value shown in Fig. 4 (b) on each structural element that constitutes π type high pass filter.Shown in figure, almost do not decay in the UHF broadcast band and on more than or equal to the frequency band of this frequency band, and on the end of UHF broadcast band lower frequency side, towards the about 30dB of 300MHz decay, and obtained required high pass filter characteristic.And, go up the formation trap at the service band (330MHz) of specific low-power wireless machine frequency band (322MHz) and analog cordless telephone machine tool.
As mentioned above, according to present embodiment, be not arranged in parallel the VHF broadcast band as the band pass filter of passband with the high pass filter of UHF broadcast band as passband, also can realize to select the high frequency filter of VHF broadcast band and UHF broadcast band, and can realize the reduction of miniaturization and cost because of the reduction of parts number of packages.And, by the 1st, the 2nd, 3PIN diode D1, D2, D3 are changeable is, the band pass filter of decay FM frequency band and UHF broadcast band when selecting the VHF broadcast band, and decay comprises the high pass filter of the frequency band of FM frequency band and VHF broadcast band when selecting the UHF broadcast band, thereby also can cut down the parts number of packages of diode.
In addition, also be out of question if the decay of the specific low-power wireless machine frequency band the when decay of the FM frequency band when selecting the VHF broadcast band or selection UHF broadcast band and near the service band (322～330MHz) of analog cordless telephone machine tool is very little, can also delete the 6th and the 7th capacitor C6, C7 so.
Fig. 6 is for deleting the structure chart of the 6th and the 7th capacitor C6, C7 (24pF) alterable band-pass filter afterwards.In addition, used two opposite power supply 5a, 5b of height to replace commutation circuit 3.The numerical value of each structural element of formation alterable band-pass filter is identical with the numerical value of above-mentioned execution mode.
Fig. 7 (a) is the alterable band-pass filter at Fig. 6, connects the 1st, 2PIN diode D1, D2 (power supply 5b=H) and disconnect 3PIN diode D3 (power supply 5a=L) and its frequency characteristic figure when having selected low-frequency range.As shown in the drawing, represented the pass band filter characteristic of VHF broadcast band as passband.But, on the FM frequency band, do not form trap.
Fig. 7 (b) is that the alterable band-pass filter at Fig. 6 breaks the 1st, 2PIN diode D1, D2 (power supply 5b=L) and connect 3PIN diode D3 (power supply 5a=H) and its frequency characteristic figure when selecting high band.Shown in figure, having represented will be more than or equal to the frequency band of the UHF broadcast band high pass filter characteristic as passband.But, go up not fully decay near the service band (322～330MHz) of specific low-power wireless machine frequency band and analog cordless telephone machine tool.
As mentioned above, even delete the 6th and the 7th capacitor C6, C7, not being arranged in parallel band pass filter and the UHF broadcast band that the VHF broadcast band is a passband is the high pass filter of passband, also can realize selecting the high frequency filter of VHF broadcast band and UHF broadcast band.
In addition, the present invention not only is subject to above-mentioned a kind of execution mode, can carry out various distortion and implement in the scope that does not break away from main idea of the present invention.For example, the 1st, the 2nd, the 3rd switch not only is subject to PIN diode, can also use other switch parts.And, can also turn the 1st, the 2nd around, the position relation between the 3PIN diode D1, D2, D3 and the 4th, the 5th, the 8th capacitor C4, C5, C8.
And, when carrying out the simulation of above-mentioned frequency characteristic, set the numerical value that VHF broadcast band and UHF broadcast band according to Japan are optimized, but but the numerical value that set basis purposes and purpose are suitably optimized.And, as long as its purposes also can be suitable on the filter beyond the high frequency filter of TV tuner for switching band pass filter and high pass filter.
The present invention is applicable on the high frequency filter that switches band pass filter and high pass filter.
Claims (5)
1, a kind of alterable band-pass filter is characterized in that,
Possess: the 1st capacitor, an end is connected with input terminal;
The 2nd capacitor, an end is connected with the other end of above-mentioned the 1st capacitor;
The 3rd capacitor is connected between the other end and lead-out terminal of above-mentioned the 2nd capacitor;
The 1st inductance, an end is connected with tie point between above-mentioned the 1st capacitor and above-mentioned the 2nd capacitor;
The 4th capacitor is connected between above-mentioned the 1st inductance and the ground connection;
The 1st switch is connected an end of above-mentioned the 4th capacitor and above-mentioned the 1st inductance or disconnects;
The 2nd inductance, an end is connected with tie point between above-mentioned the 2nd capacitor and above-mentioned the 3rd capacitor;
The 5th capacitor is connected between above-mentioned the 2nd inductance and the ground connection;
The 2nd switch is connected an end of above-mentioned the 5th capacitor and above-mentioned the 2nd inductance or disconnects;
The 3rd inductance is connected between the other end and ground connection of the other end of above-mentioned the 1st inductance and above-mentioned the 2nd inductance; And
The 3rd switch is connected in parallel with above-mentioned the 3rd inductance, and the two ends of above-mentioned the 3rd inductance of high frequency short circuit,
And, disconnect above-mentioned the 3rd switch when connecting the above-mentioned the 1st and the 2nd switch and form band pass filter, connect above-mentioned the 3rd switch when disconnecting the above-mentioned the 1st and the 2nd switch and form the high pass filter that passband is higher than above-mentioned band pass filter.
2, alterable band-pass filter according to claim 1 is characterized in that,
Possess: the 6th capacitor is connected the connection between the above-mentioned the 1st and the 2nd capacitor
Between one end of point and above-mentioned the 1st inductance; And
The 7th capacitor is connected between the end of tie point between the above-mentioned the 2nd and the 3rd capacitor and above-mentioned the 2nd inductance,
And, disconnect above-mentioned the 3rd switch when connecting the above-mentioned the 1st and the 2nd switch and when having formed band pass filter, form pad electrode to be in than the trap circuit on the low frequency of the passband of this band pass filter,
Connect above-mentioned the 3rd switch when disconnecting the above-mentioned the 1st and the 2nd switch and when having formed passband and being higher than the high pass filter of above-mentioned band pass filter, form pad electrode and be in than the trap circuit on the low frequency of the passband of this high pass filter.
3, alterable band-pass filter according to claim 1 is characterized in that,
The the 1st and the 2nd switching diode that the above-mentioned the 1st and the 2nd switch is constituted by a diode respectively constitutes,
Above-mentioned the 1st switching diode, its anode is connected with above-mentioned the 4th capacitor and its negative electrode is connected with an end of above-mentioned the 1st inductance,
Above-mentioned the 2nd switching diode, its anode is connected with above-mentioned the 5th capacitor and its negative electrode is connected with an end of above-mentioned the 2nd inductance,
Control voltage be applied to the above-mentioned the 1st and the anode of the 2nd switching diode on.
4, alterable band-pass filter according to claim 1 is characterized in that,
Above-mentioned the 3rd switch is made of the 3rd switching diode and the 8th capacitor, and the 3rd switching diode is made of diode, and the 8th capacitor is used to block direct current and an end is connected with the anode of the 3rd switching diode,
Above-mentioned the 3rd switching diode, its negative electrode is connected with tie point between above-mentioned the 1st, the 2nd, the 3rd inductance,
One end of above-mentioned the 8th capacitor is connected with ground connection,
Control voltage is applied on the anode of above-mentioned the 3rd switching diode.
5, according to any described alterable band-pass filter in the claim 1 to 4, it is characterized in that,
Passband when disconnecting above-mentioned the 3rd switch when connecting the above-mentioned the 1st and the 2nd switch is the VHF broadcast band,
Passband when connecting above-mentioned the 3rd switch when disconnecting the above-mentioned the 1st and the 2nd switch is more than or equal to uhf band.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP060472/2007 | 2007-03-09 | ||
| JP2007060472A JP4713523B2 (en) | 2007-03-09 | 2007-03-09 | Bandwidth variable filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101262209A true CN101262209A (en) | 2008-09-10 |
| CN101262209B CN101262209B (en) | 2010-06-16 |
Family
ID=39845839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200810082192XA Expired - Fee Related CN101262209B (en) | 2007-03-09 | 2008-03-07 | Alterable band-pass filter |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP4713523B2 (en) |
| CN (1) | CN101262209B (en) |
| TW (1) | TW200901623A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103795939A (en) * | 2014-01-22 | 2014-05-14 | 中国科学院长春光学精密机械与物理研究所 | Sampling system using variable band pass filter and double- correlation sampling method |
| CN113014222A (en) * | 2021-04-26 | 2021-06-22 | 哈尔滨海能达科技有限公司 | Band-pass filter circuit and electronic equipment |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI470928B (en) | 2009-09-02 | 2015-01-21 | Mstar Semiconductor Inc | Tuner and its front-end circuit |
| WO2017043155A1 (en) | 2015-09-09 | 2017-03-16 | 株式会社村田製作所 | Variable-frequency lc filter, high-frequency front end circuit |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56103514A (en) * | 1980-01-23 | 1981-08-18 | Hitachi Ltd | Filter circuit |
| JPS61239727A (en) * | 1985-04-17 | 1986-10-25 | Hitachi Ltd | Input circuit of tuner |
| JPH06334463A (en) * | 1993-05-26 | 1994-12-02 | Toshiba Corp | Band changeover circuit |
| JP2846240B2 (en) * | 1994-05-20 | 1999-01-13 | 国際電気株式会社 | Variable frequency band filter |
| JP3570375B2 (en) * | 2000-04-19 | 2004-09-29 | 株式会社村田製作所 | Frequency variable filter, antenna duplexer and communication device |
-
2007
- 2007-03-09 JP JP2007060472A patent/JP4713523B2/en active Active
-
2008
- 2008-02-26 TW TW97106641A patent/TW200901623A/en unknown
- 2008-03-07 CN CN200810082192XA patent/CN101262209B/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103795939A (en) * | 2014-01-22 | 2014-05-14 | 中国科学院长春光学精密机械与物理研究所 | Sampling system using variable band pass filter and double- correlation sampling method |
| CN113014222A (en) * | 2021-04-26 | 2021-06-22 | 哈尔滨海能达科技有限公司 | Band-pass filter circuit and electronic equipment |
| CN113014222B (en) * | 2021-04-26 | 2023-08-08 | 哈尔滨海能达科技有限公司 | Band-pass filter circuit and electronic equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4713523B2 (en) | 2011-06-29 |
| CN101262209B (en) | 2010-06-16 |
| TWI342669B (en) | 2011-05-21 |
| JP2008227729A (en) | 2008-09-25 |
| TW200901623A (en) | 2009-01-01 |
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