CN109687838A - A kind of high speed response type low-pass filter, filter circuit and control method - Google Patents
A kind of high speed response type low-pass filter, filter circuit and control method Download PDFInfo
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- CN109687838A CN109687838A CN201811554907.7A CN201811554907A CN109687838A CN 109687838 A CN109687838 A CN 109687838A CN 201811554907 A CN201811554907 A CN 201811554907A CN 109687838 A CN109687838 A CN 109687838A
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- switch
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- amplifier
- pass filter
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H11/12—Frequency selective two-port networks using amplifiers with feedback
- H03H11/126—Frequency selective two-port networks using amplifiers with feedback using a single operational amplifier
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Abstract
The invention discloses a kind of high speed response type low-pass filters, it includes amplifier U1 and the switch Φ b1 that is sequentially connected in series, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3, input terminal of the front end of the switch Φ b1 as the low-pass filter, the rear end of the switch Φ b1 is grounded by capacitor C1, the rear end of the switch Φ a1 is grounded by capacitor C2, the rear end of the switch Φ b2 is grounded by capacitor C3, the rear end of the switch Φ b3 is grounded by capacitor C4, the rear end of the switch Φ a3 is connected to the in-phase end of the amplifier U1, the rear end of the switch Φ a2 is connected to the output end of the amplifier U1 phase by capacitor C5, output after output end and the reverse side interconnection of the U1 of the amplifier as the low-pass filter End.The present invention reduces the angular frequency of low-pass filtering under conditions of not reducing channel switch speed, and then reduces noise to signal adverse effect.
Description
Technical field
The present invention relates to low-pass filter more particularly to a kind of high speed response type low-pass filters, filter circuit and control
Method.
Background technique
Filter is used in signal processing circuit extensively, is used in analog signal processing and communication field, filter
Cross noise filtering, communication field be used for different frequency range separate and handle, especially in terms of wireless telecommunications, signal be all with
Carrier wave is launched after being first mixed device mixing, and signal is passed through filter by recipient, and carrier signal is filtered to have in advance
Message.As soon as in general, section filter is 20dB/decade, and three meet filter also 60dB/decade, so angular frequency
Ten times of gap is had to the frequency for lifting signal.But when the too low output signal of angular frequency will react very slowly.And
And will ceaselessly switch in the different channel of touch chip, low-pass filtering ask that the waiting time that output needs to grow very much, this
The speed of chip will be kept very slow, to reduce the performance of chip.Since power supply noise and LCD screen noise are all very low frequency, institute
It is to be unable to reach so low frequency there are also enough reactions with general low-pass filter.
Existing low-pass filter circuit structure is referring to Figure 1 to Fig. 3, in the AFE(analog front end) of many sensors, filter quilt
For filter high-frequency noise, such as noise caused by radio frequency noise, power noise and other systems.But many noises
For example power noise etc. is all the noise of low frequency, needs the low-frequency filter of the very angular frequency of low frequency.In practical application, low pass filtered
Wave device can there are many kinds of, simplest is RC low-pass filter, still, the poor performance of this filter, under angular frequency
Sliding very slow, only 20dB/decade.In order to improve the lower slippery of angular frequency, therefore the filter of high rank is used, such as 2
Class, even higher class, 3 classes, refer to Fig. 3, and the filter of high rank is to use resistance capacitance network, and these are filtered
What the angular frequency of device can be got with tuple polynomial mathematical equation.But the band of this passive type filter carries energy
Power is mutually on duty, it is difficult to meet application demand.
Summary of the invention
The technical problem to be solved in the present invention is that in view of the deficiencies of the prior art, provides and a kind of cut not reducing channel
Under conditions of throw-over degree, the angular frequency of low-pass filtering is reduced, and then it is low to the dysgenic high speed response type of signal to reduce noise
Bandpass filter, filter circuit and control method.
In order to solve the above technical problems, the present invention adopts the following technical scheme that.
A kind of high speed response type low-pass filter comprising have amplifier U1 and be sequentially connected in series switch Φ b1, switch Φ a1,
Switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3, the front end of the switch Φ b1 is as the defeated of the low-pass filter
Enter end, the rear end of the switch Φ b1 is grounded by capacitor C1, and the rear end of the switch Φ a1 is grounded by capacitor C2, described to open
The rear end for closing Φ b2 is grounded by capacitor C3, and the rear end of the switch Φ b3 is grounded by capacitor C4, after the switch Φ a3
End is connected to the in-phase end of the amplifier U1, and the rear end of the switch Φ a2 is connected to the defeated of the amplifier U1 phase by capacitor C5
Outlet, the output end after output end and the reverse side interconnection of the U1 of the amplifier as the low-pass filter.
Preferably, switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3 are equal
For program controlled switch.
A kind of filter circuit comprising have reverse amplifier, low-pass filter and analog-digital converter, the reverse amplifier
Input terminal be connected to capacitance touch screen, the output end of the reverse amplifier is connected to the low-pass filter, the low pass
The output end of filter is connected to the analog-digital converter, and the low-pass filter is low-pass filtering of any of claims 1 or 2
Device.
Preferably, rectifier is serially connected between the reverse amplifier and the low-pass filter.
A kind of control method of filter circuit, this method realize that the filter circuit includes inverse based on a filter circuit
To amplifier, low-pass filter and analog-digital converter, the input terminal of the reverse amplifier is connected to capacitance touch screen, described inverse
It is connected to the low-pass filter to the output end of amplifier, the output end of the low-pass filter is connected to the analog-to-digital conversion
Device, the low-pass filter include amplifier U1 and be sequentially connected in series switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2,
Switch Φ b3 and switch Φ a3, input terminal of the front end of the switch Φ b1 as the low-pass filter, the switch Φ b1
Rear end be grounded by capacitor C1, the rear end of the switch Φ a1 is grounded by capacitor C2, and the rear end of the switch Φ b2 passes through
Capacitor C3 ground connection, the rear end of the switch Φ b3 are grounded by capacitor C4, and the rear end of the switch Φ a3 is connected to the amplifier
The rear end of the in-phase end of U1, the switch Φ a2 is connected to the output end of the amplifier U1 phase by capacitor C5, the amplifier
Output end after output end and the reverse side interconnection of U1 as the low-pass filter, which comprises pass through control
The on off operating mode of switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3, to enable the low pass
Filter realizes low-pass filtering.
High speed response type low-pass filter disclosed by the invention, which employs the low pass filtereds of traditional sallen-key three-level
Wave device structure, and using switching capacity instead of whole resistance, when carrying out low-pass filtering using switching capacity, only can signal compared with
It is sampled when good, this circuit design makes low-pass filter possess the function of rectifier, and the angle of low-pass filtering
Frequency can be controlled with different clock frequencies.In addition, when switching at high speed channel, the reaction of low-pass filtering can it is very slow so
Need the longer waiting time.For the present invention when channel switches, the clock of filter will be in the very of short duration time using high speed
Clock causes the angular frequency of low-pass filter is of short duration to be enhanced, so that circuit reaction is accelerated, and the output in low-pass filtering is anti-
When should come, clock is lowered to original frequency, and filter then can normally filter out the noise of angular frequency or more at this time.
Detailed description of the invention
Fig. 1 is the circuit diagram one of existing low-pass filter；
Fig. 2 is the circuit diagram two of existing low-pass filter；
Fig. 3 is the circuit diagram three of existing low-pass filter；
Fig. 4 is the waveform diagram of existing low-pass filter filtering；
Fig. 5 is the circuit diagram of low-pass filter of the present invention；
Fig. 6 is filter circuit schematic diagram of the present invention；
Fig. 7 is the schematic diagram of filter circuit in the preferred embodiment of the present invention；
Fig. 8 is the waveform diagram one of filter circuit filtering of the present invention；
Fig. 9 is the waveform diagram two of filter circuit filtering of the present invention；
Figure 10 is the waveform diagram three of filter circuit filtering of the present invention；
Figure 11 is the waveform diagram four of filter circuit filtering of the present invention.
Specific embodiment
The present invention is described in more detail with reference to the accompanying drawings and examples.
The invention discloses a kind of high speed response type low-pass filters, refer to Fig. 5 comprising have amplifier U1 and successively
Before concatenated switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3, the switch Φ b1
The input terminal as the low-pass filter is held, the rear end of the switch Φ b1 is grounded by capacitor C1, the switch Φ a1's
Rear end is grounded by capacitor C2, and the rear end of the switch Φ b2 is grounded by capacitor C3, and the rear end of the switch Φ b3 passes through electricity
Hold C4 ground connection, the rear end of the switch Φ a3 is connected to the in-phase end of the amplifier U1, and the rear end of the switch Φ a2 passes through electricity
Hold the output end that C5 is connected to the amplifier U1 phase, the output end and reverse side of the U1 of the amplifier is used as described after being connected with each other
The output end of low-pass filter.
Above-mentioned low-pass filter, which employs the low-pass filter structures of traditional sallen-key three-level, and utilize and open
It is powered-down to hold instead of whole resistance, when carrying out low-pass filtering using switching capacity, it can only be sampled when signal is preferable,
This circuit design makes low-pass filter possess the function of rectifier, and the angular frequency of low-pass filtering can with it is different when
Clock frequency controls.In addition, the reaction of low-pass filtering can be very slow so when needing longer waiting when switching at high speed channel
Between.For the present invention when channel switches, the clock of filter will use high-frequency clock in the very of short duration time, cause low-pass filtering
The angular frequency of device is of short duration to be enhanced, so that circuit reaction is accelerated, and when the output-response of low-pass filtering comes, clock is dropped
As low as original frequency, filter then can normally filter out the noise of angular frequency or more at this time.
In practical application, for the ease of controlling switching state, in the present embodiment, switch Φ b1, switch Φ a1, switch
Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3 are program controlled switch.
The invention further relates to a kind of filter circuits, refer to Fig. 6, include reverse amplifier 2, low-pass filter 3 and mould
Number converter 4, the input terminal of the reverse amplifier 2 are connected to capacitance touch screen 1, and the output end of the reverse amplifier 2 connects
It is connected to the low-pass filter 3, the output end of the low-pass filter 3 is connected to the analog-digital converter 4, the low-pass filtering
Device 3 is low-pass filter of any of claims 1 or 2.
Refer to Fig. 4, the clock of existing filter be it is continuous, in the course of work, once input signal frequency is filtering
More than the angular frequency of device, then whole signals all will be filtered, and output just only has VREF, that is, the average value of input signal, be
Solve the problems, such as this, the present embodiment added a rectifier between CA and filter.Refer to Fig. 7, the reverse amplification
Rectifier 5 is serially connected between device 2 and the low-pass filter 3, waveform diagram refers to Fig. 8.But in actual application,
Fig. 9 is referred to, if the clock of filter is only opened when CA is high or low, the output signal of CA only exists
The top half of VREF can just be passed through.Referring to Figure 10, when the clock of filter is when CA is low, effect and CA signal quilt
After a rectifier rectification into filter effect be it is the same, pass through this control method, capacitance switch filter
Substantially it can be omitted rectifier.Referring to Figure 11, it, can be the reaction of output signal if the clock frequency of front is improved
Also it improves.
Based on the above principles, the invention further relates to a kind of control method of filter circuit, this method is based on a filter circuit
It realizes, the filter circuit includes reverse amplifier 2, low-pass filter 3 and analog-digital converter 4, the reverse amplifier 2
Input terminal is connected to capacitance touch screen 1, and the output end of the reverse amplifier 2 is connected to the low-pass filter 3, the low pass
The output end of filter 3 is connected to the analog-digital converter 4, and the low-pass filter 3 includes amplifier U1 and is sequentially connected in series
Switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3, the front end conduct of the switch Φ b1
The rear end of the input terminal of the low-pass filter, the switch Φ b1 is grounded by capacitor C1, and the rear end of the switch Φ a1 is logical
Capacitor C2 ground connection is crossed, the rear end of the switch Φ b2 is grounded by capacitor C3, and the rear end of the switch Φ b3 is connect by capacitor C4
Ground, the rear end of the switch Φ a3 are connected to the in-phase end of the amplifier U1, and the rear end of the switch Φ a2 is connected by capacitor C5
It is connected to the output end of the amplifier U1 phase, the output end and reverse side of the U1 of the amplifier is used as the low pass filtered after being connected with each other
The output end of wave device, which comprises
Pass through the on-off of control switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3
State, to enable the low-pass filter 3 realize low-pass filtering.
High speed response type low-pass filter, filter circuit and control method disclosed by the invention, compared with prior art and
The beneficial effect of speech is that present invention employs switching capacities to carry out real 3 grades of filters, uses adjustable switching frequency to adjust
The angular frequency of filter is controlled, but also higher reaction speed can be reached, has better meet application demand.
The above is preferred embodiments of the present invention, is not intended to restrict the invention, all in technology model of the invention
Interior done modification, equivalent replacement or improvement etc. are enclosed, should be included in the range of of the invention protect.
Claims (5)
1. a kind of high speed response type low-pass filter, which is characterized in that include amplifier U1 and switch Φ b1 being sequentially connected in series, open
Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3 are closed, the front end of the switch Φ b1 is as the low pass filtered
The rear end of the input terminal of wave device, the switch Φ b1 is grounded by capacitor C1, and the rear end of the switch Φ a1 is connect by capacitor C2
The rear end on ground, the switch Φ b2 is grounded by capacitor C3, and the rear end of the switch Φ b3 is grounded by capacitor C4, the switch
The rear end of Φ a3 is connected to the in-phase end of the amplifier U1, and the rear end of the switch Φ a2 is connected to the amplifier by capacitor C5
The output end of U1 phase, the output after output end and the reverse side interconnection of the U1 of the amplifier as the low-pass filter
End.
2. high speed response type low-pass filter as described in claim 1, which is characterized in that switch Φ b1, switch Φ a1,
Switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3 are program controlled switch.
3. a kind of filter circuit, which is characterized in that include reverse amplifier (2), low-pass filter (3) and analog-digital converter
(4), the input terminal of the reverse amplifier (2) is connected to capacitance touch screen (1), and the output end of the reverse amplifier (2) connects
It is connected to the low-pass filter (3), the output end of the low-pass filter (3) is connected to the analog-digital converter (4), described low
Bandpass filter (3) is low-pass filter of any of claims 1 or 2.
4. filter circuit as claimed in claim 3, which is characterized in that the reverse amplifier (2) and the low-pass filter
(3) rectifier (5) are serially connected between.
5. a kind of control method of filter circuit, which is characterized in that this method is based on filter circuit realization, the filter circuit
It include reverse amplifier (2), low-pass filter (3) and analog-digital converter (4), the input terminal of the reverse amplifier (2) connects
It is connected to capacitance touch screen (1), the output end of the reverse amplifier (2) is connected to the low-pass filter (3), the low pass filtered
The output end of wave device (3) is connected to the analog-digital converter (4), and the low-pass filter (3) includes amplifier U1 and successively goes here and there
Switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and the switch Φ a3 of connection, the front end of the switch Φ b1
As the input terminal of the low-pass filter, the rear end of the switch Φ b1 is grounded by capacitor C1, after the switch Φ a1
End is grounded by capacitor C2, and the rear end of the switch Φ b2 is grounded by capacitor C3, and the rear end of the switch Φ b3 passes through capacitor
C4 ground connection, the rear end of the switch Φ a3 are connected to the in-phase end of the amplifier U1, and the rear end of the switch Φ a2 passes through capacitor
C5 is connected to the output end of the amplifier U1 phase, and the output end and reverse side of the U1 of the amplifier is used as described low after being connected with each other
The output end of bandpass filter, which comprises
By the on off operating mode of control switch Φ b1, switch Φ a1, switch Φ b2, switch Φ a2, switch Φ b3 and switch Φ a3,
To enable the low-pass filter (3) to realize low-pass filtering.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811554907.7A CN109687838A (en) | 2018-12-18 | 2018-12-18 | A kind of high speed response type low-pass filter, filter circuit and control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811554907.7A CN109687838A (en) | 2018-12-18 | 2018-12-18 | A kind of high speed response type low-pass filter, filter circuit and control method |
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| Publication Number | Publication Date |
|---|---|
| CN109687838A true CN109687838A (en) | 2019-04-26 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201811554907.7A Pending CN109687838A (en) | 2018-12-18 | 2018-12-18 | A kind of high speed response type low-pass filter, filter circuit and control method |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102809670A (en) * | 2012-08-20 | 2012-12-05 | 中国兵器工业集团第二一四研究所苏州研发中心 | Monolithic open-loop integrated circuit of acceleration sensor |
| CN105115606A (en) * | 2015-05-21 | 2015-12-02 | 常州大学 | Two-stage reading circuit based on relaxation ferroelectric monocrystalline pyroelectric detector |
| CN106524891A (en) * | 2016-12-27 | 2017-03-22 | 广州市淞滨工程技术有限公司 | Signal processing circuit applied to inductive sensor |
-
2018
- 2018-12-18 CN CN201811554907.7A patent/CN109687838A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102809670A (en) * | 2012-08-20 | 2012-12-05 | 中国兵器工业集团第二一四研究所苏州研发中心 | Monolithic open-loop integrated circuit of acceleration sensor |
| CN105115606A (en) * | 2015-05-21 | 2015-12-02 | 常州大学 | Two-stage reading circuit based on relaxation ferroelectric monocrystalline pyroelectric detector |
| CN106524891A (en) * | 2016-12-27 | 2017-03-22 | 广州市淞滨工程技术有限公司 | Signal processing circuit applied to inductive sensor |
Non-Patent Citations (1)
| Title |
|---|
| 刘波文: "《模拟电路》", 31 July 2014, 北京航空航天大学出版社 * |
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