CN106470022A - A kind of filter circuit and method - Google Patents
A kind of filter circuit and method Download PDFInfo
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- CN106470022A CN106470022A CN201510502257.1A CN201510502257A CN106470022A CN 106470022 A CN106470022 A CN 106470022A CN 201510502257 A CN201510502257 A CN 201510502257A CN 106470022 A CN106470022 A CN 106470022A
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H17/00—Networks using digital techniques
- H03H17/02—Frequency selective networks
- H03H17/04—Recursive filters
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Abstract
The invention discloses a kind of filter circuit and method.This filter circuit, including：First integral wave filter, the first combed filter device and decimator, wherein, the input of described decimator is connected with the outfan of described first integral wave filter, and the outfan of described decimator is connected with the first input end of described first combed filter device.Before achieving the down-sampled device in combed filter, thus decreasing the complexity of combed filter device.
Description
Technical field
The present invention relates to digital circuit field, espespecially a kind of filter circuit and method.
Background technology
Digital microphone is a kind of processing meanss that simulated audio signal is converted to digital audio and video signals, its
In, the digital audio and video signals of digital microphone output are pulse density modulated (Pulse Density
Modulation, abbreviation PDM) form.
Generally, the several audio processing equipments being connected with digital microphone and playback equipment all only support that pulse is compiled
Code modulation (Pulse Code Modulation, abbreviation PCM), thus need to be converted to PDM signal
PCM signal.The method that existing PDM turns PCM can be using cascade integral dressing (CIC) filtering knot
Structure.
However, those skilled in the art find, by existing skill during stating prior art in realization
When the filter circuit of art carries out signal processing, need to take substantial amounts of internal memory, thus causing combed filter device
Complex structure.
Content of the invention
In order to solve above-mentioned technical problem, the invention provides a kind of filter circuit and method, in order to solve
Receive the baroque problem of combed filter device.
In order to reach the object of the invention, the invention provides a kind of filter circuit, including：1st, a kind of filter
Wave circuit is it is characterised in that include：First integral wave filter, the first combed filter device and down-sampled
Device, wherein,
The input of described decimator is connected with the outfan of described first integral wave filter, and described fall is adopted
The outfan of sample device is connected with the first input end of described first combed filter device.
Further, described first integral wave filter, including：Integrator and the first chronotron；Wherein,
The outfan of described first chronotron is connected with the first input end of described integrator, and described first prolongs
When device input be connected with the outfan of described integrator；
The outfan of described integrator is connected with the input of described decimator.
Further, described first combed filter device, including：Subtractor and the second chronotron；Wherein,
The outfan of described second chronotron is connected with the negative input end of described subtractor, described second time delay
The input of device is connected with the positive input terminal of described subtractor.
Further, also include at least one second integral wave filter, described second integral wave filter defeated
Go out end to be connected with the second input of described first integral wave filter.
Further, also include at least one second combed filter device, described second combed filter device defeated
Go out end to be connected with the second input of described first combed filter device.
Further, the time delay of described first chronotron is 1 unit.
Further, the down-sampled frequency of described decimator is R, and R is equal to the result divided by N for the M,
Described M is the working clock frequency used by described integrator, and described N is the work used by described subtractor
Clock frequency.
The invention provides a kind of filtering method, including：
Obtain the first filtering signal of first integral wave filter output；
Described first filtering signal is carried out dropping down-sampled process, obtains down-sampled signal；
By described down-sampled signal input the first combed filter device, obtain the second filtering signal.
Further, before the first filtering signal of described acquisition first integral wave filter output, also include：
Obtain at least one second integral wave filter output the 3rd filtering signal, described at least one second
Each second integral wave filter in integration filter is connected by way of cascade with described first integral wave filter
Connect.
Further, described by described down-sampled signal input the first combed filter device, obtain the second filtering
After signal, also include：
Described second filtering signal is inputted at least one second combed filter device, obtains the 4th filtering signal,
The second combed filter device at least one second combed filter device described is led to described first combed filter device
The mode crossing cascade connects.
In the present embodiment, filter circuit, including：First integral wave filter, the first combed filter device and
Decimator, wherein, the input of described decimator is connected with the outfan of described first integral wave filter
Connect, the outfan of described decimator is connected with the first input end of described first combed filter device.Realize
Before the down-sampled device in combed filter, thus decrease the complexity of combed filter device.
Other features and advantages of the present invention will illustrate in the following description, and, partly from froming the perspective of
Become apparent in bright book, or understood by implementing the present invention.The purpose of the present invention is excellent with other
Point can be realized by specifically noted structure in description, claims and accompanying drawing and obtain
?.
Brief description
Accompanying drawing is used for providing technical solution of the present invention is further understood, and constitutes one of description
Point, it is used for explaining technical scheme together with embodiments herein, do not constitute to the present invention
The restriction of technical scheme.
Fig. 1 is the structural representation of filter circuit one embodiment of the present invention；
Fig. 2 is the structural representation of filter circuit two embodiment of the present invention；
Fig. 3 is the structural representation of filter circuit three embodiment of the present invention；
Fig. 4 is the structural representation of filtering method one embodiment of the present invention.
Specific embodiment
For making the object, technical solutions and advantages of the present invention become more apparent, below in conjunction with accompanying drawing
Embodiments of the invention are described in detail.It should be noted that in the case of not conflicting, this Shen
Please in embodiment and the feature in embodiment can mutual combination in any.
Fig. 1 is the structural representation of filter circuit one embodiment of the present invention, as shown in figure 1, filtered electrical
Road, including：First integral wave filter, the first combed filter device and decimator, wherein,
The input of described decimator is connected with the outfan of described first integral wave filter, and described fall is adopted
The outfan of sample device is connected with the first input end of described first combed filter device.
Specifically, the digital audio and video signals of PDM are input to first integral wave filter, and from first integral filter
The outfan of ripple device exports the first output signal, then, the first output signal is defeated from decimator one end
Enter, down-sampled by decimator, export the second output signal from the other end of decimator, then connect
, the second output signal inputs combed filter device by the first input end of combed filter device, then obtains
The digital audio and video signals of PCM.
From down-sampled extract output after, enter cascade combed filter device, the time delay of the first combed filter device by
Greatly reduce in down-sampled reach, for example, it is assumed that the time delay of comb the first shape wave filter of prior art
For 8, down-sampled rate is 8, then input/output relation is expressed as：
Z (N)=y (N)-y (N-8), wherein,
Z (N) is the output signal of the first comb filter, and y (N) is the input signal of the first comb filter,
Y (N-8) is the input signal of the input first integral wave filter by the second chronotron；
The time delay of first comb filter of the present invention is changed into the ratio of former time delay and down-sampled rate, that is,
1, input/output relation is expressed as
Z (N)=y (N)-y (N-1), wherein,
Z (N) is the output signal of the first comb filter, and y (N) is the input signal of the first comb filter,
Y (N-1) is the input signal of the input first integral wave filter by the second chronotron.
It can be seen that the time delay of the first combed filter reduces a lot after improving, this means in side circuit
The number preserving data required for greatly reduces, and also just simplifies circuit structure and the resource taking.
In the present embodiment, filter circuit, including：First integral wave filter, the first combed filter device and
Decimator, wherein, the input of described decimator is connected with the outfan of described first integral wave filter
Connect, the outfan of described decimator is connected with the first input end of described first combed filter device.Realize
Before the down-sampled device in combed filter, thus decrease the complexity of combed filter device.
Fig. 2 is the structural representation of filter circuit two embodiment of the present invention, as shown in Fig. 2 above-mentioned
On the basis of embodiment, first integral wave filter, can include：Integrator and the first chronotron；Wherein,
The outfan of described first chronotron is connected with the first input end of described integrator, described first chronotron
Input be connected with the outfan of described integrator, the outfan of integrator is defeated with described decimator
Enter end to connect.
First combed filter device, can include：Subtractor and the second chronotron；Wherein, described second prolongs
When device outfan defeated with the first of described subtractor such as enter end be connected, the other end of described second chronotron
It is connected with the positive input terminal of described subtractor.
For example, the first input signal and the second input signal are respectively by the first input end of integrator
With the second input input to integrator, obtain the first output signal, wherein, the second input signal is first
Input signal passes through the signal that the first chronotron obtains, and then, the first output signal is taken out by decimator
Take R, followed by the signal of decimator output is divided into two-way, and a road is directly inputted to input subtractor
The second input, be input to after separately leading up to the second chronotron time delay this subtractor first input
End, subtractor exports the second output signal.
Fig. 3 is the structural representation of filter circuit three embodiment of the present invention, as shown in figure 3, above-mentioned
On the basis of embodiment, filter circuit, also include at least one second combed filter device, described second comb
The outfan of adornment wave filter is connected with the second input of described first combed filter device.
Further, the time delay of described first chronotron is 1 unit.
Further, the down-sampled frequency of described decimator is R, and R is equal to the result divided by N for the M,
Described M is the working clock frequency used by described integrator, and described N is the work used by described subtractor
Clock frequency.
For example, the implementation of the present embodiment comprises the following steps：
(1) PDM digital audio and video signals are input to multi-stage integrator, and the time delay of integrator is 1, that is, each
The current output of level integration filter is equal to current input and last output sum,
Y (n)=x (n)+y (n-1), wherein,
Y (n) is the output signal of integration filter, and x (n) is the input signal of integration filter, and y (n-1) is
Input signal by the input integral wave filter of the first chronotron；
(2) after cascade integrator output, through R times of down-sampled extraction, data amount check is changed into originally individual
The 1/R of number.Down-sampled can change to realize by clock frequency：Working clock frequency used by integrator
For M, the working clock frequency used by comb filter is N, and meets M=NxR, then enter
The data amount check of combed filter device is it is simply that the 1/R of data amount check from integrator output.
By down-sampled rear signalWherein, y (n) is down-sampled
Front signal；
(3) from down-sampled extract output after, enter cascade combed filter device, the time delay of combed filter device by
Greatly reduce in down-sampled reach, for example, it is assumed that the time delay of the comb filter of prior art is 8,
Down-sampled rate is 8, then input/output relation is expressed as：
Z (N)=y (N)-y (N-8) wherein,
Z (N) is the output signal of comb filter, and y (N) is the input signal of comb filter, y (N-8)
It is the input signal of the input integral wave filter by the second chronotron；
The time delay of the comb filter of the present invention is changed into the ratio of former time delay and down-sampled rate, that is, 1, defeated
Enter output relation to be expressed as
In z (N)=y (N)-y (N-1),
Z (N) is the output signal of comb filter, and y (N) is the input signal of comb filter, y (N-1)
It is the input signal of the input integral wave filter by the second chronotron.
It can be seen that the time delay of combed filter reduces a lot after improving, this means institute in side circuit
Need the number preserving data to greatly reduce, also just simplify circuit structure and the resource taking.
Fig. 4 is the structural representation of filtering method one embodiment of the present invention, as shown in figure 4, this filtering
Method, including：
Step 401, the first filtering signal of acquisition first integral wave filter output.
Step 402, described first filtering signal is carried out down-sampled process, obtain down-sampled signal.
Step 403, by described down-sampled signal input the first combed filter device, obtain the second filtering signal.
Specifically, the digital audio and video signals of PDM are input to first integral wave filter, and from first integral filter
The outfan of ripple device exports the first output signal, then, the first output signal is defeated from decimator one end
Enter, down-sampled by decimator, export the second output signal from the other end of decimator, then connect
, the second output signal inputs combed filter device by the first input end of combed filter device, then obtains
The digital audio and video signals of PCM.
In the present embodiment, by obtaining the first filtering signal of first integral wave filter output, will be described
First filtering signal carries out down-sampled process, obtains down-sampled signal, by described down-sampled signal input the
One combed filter device, obtains the second filtering signal.Before achieving the down-sampled device in combed filter, thus
Decrease the complexity of combed filter device.
Further, on the basis of above-described embodiment, obtain the first filter of first integral wave filter output
Before ripple signal, also include：
Obtain at least one second integral wave filter output the 3rd filtering signal, described at least one second
Each second integral wave filter in integration filter is connected by way of cascade with described first integral wave filter
Connect.
Optionally, on the basis of above-described embodiment, described by the dressing of described down-sampled signal input first
Wave filter, after obtaining the second filtering signal, can also include：
Described second filtering signal is inputted at least one second combed filter device, obtains the 4th filtering signal,
The second combed filter device at least one second combed filter device described is led to described first combed filter device
The mode crossing cascade connects.
In the present embodiment, the time delay of the first combed filter device and the second combed filter device combed filter reduces
A lot, this preserves data number required for meaning in side circuit greatly reduces, and also just simplifies
Circuit structure and the resource taking.
Although disclosed herein embodiment as above, described content only readily appreciates the present invention
And the embodiment adopting, it is not limited to the present invention.Technology people in any art of the present invention
Member, without departing from disclosed herein spirit and scope on the premise of, can be in the form implemented and thin
Any modification and change are carried out on section, but the scope of patent protection of the present invention, still must be with appended right
The scope that claim is defined is defined.
Claims (10)
1. a kind of filter circuit is it is characterised in that include：First integral wave filter, the first dressing filter
Ripple device and decimator, wherein,
The input of described decimator is connected with the outfan of described first integral wave filter, and described fall is adopted
The outfan of sample device is connected with the first input end of described first combed filter device.
2. filter circuit according to claim 1 is it is characterised in that described first integral wave filter,
Including：Integrator and the first chronotron；Wherein,
The outfan of described first chronotron is connected with the first input end of described integrator, and described first prolongs
When device input be connected with the outfan of described integrator；
The outfan of described integrator is connected with the input of described decimator.
3. filter circuit according to claim 2 is it is characterised in that described first combed filter device,
Including：Subtractor and the second chronotron；Wherein,
The outfan of described second chronotron is connected with the negative input end of described subtractor, described second time delay
The input of device is connected with the positive input terminal of described subtractor.
4. the filter circuit according to Claims 2 or 3 is it is characterised in that also include at least one
Second integral wave filter, the of the outfan of described second integral wave filter and described first integral wave filter
Two inputs connect.
5. the filter circuit according to any one of claim 4 is it is characterised in that also include at least one
Individual second combed filter device, the outfan of described second combed filter device and described first combed filter device
Second input connects.
6. filter circuit according to claim 5 it is characterised in that described first chronotron when
Prolong as 1 unit.
7. filter circuit according to claim 6 is it is characterised in that the fall of described decimator is adopted
Sample frequency is R, and R is equal to the result divided by N for the M, and described M is the work clock used by described integrator
Frequency, described N is the working clock frequency used by described subtractor.
8. a kind of filtering method is it is characterised in that include：
Obtain the first filtering signal of first integral wave filter output；
Described first filtering signal is carried out dropping down-sampled process, obtains down-sampled signal；
By described down-sampled signal input the first combed filter device, obtain the second filtering signal.
9. method according to claim 8 is it is characterised in that described acquisition first integral wave filter
Before first filtering signal of output, also include：
Obtain at least one second integral wave filter output the 3rd filtering signal, described at least one second
Each second integral wave filter in integration filter is connected by way of cascade with described first integral wave filter
Connect.
10. method according to claim 8 or claim 9 is it is characterised in that described will be described down-sampled
Signal input the first combed filter device, after obtaining the second filtering signal, also includes：
Described second filtering signal is inputted at least one second combed filter device, obtains the 4th filtering signal,
The second combed filter device at least one second combed filter device described is led to described first combed filter device
The mode crossing cascade connects.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510502257.1A CN106470022A (en) | 2015-08-14 | 2015-08-14 | A kind of filter circuit and method |
| PCT/CN2015/095317 WO2016131319A1 (en) | 2015-08-14 | 2015-11-23 | Filter circuit and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510502257.1A CN106470022A (en) | 2015-08-14 | 2015-08-14 | A kind of filter circuit and method |
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| Publication Number | Publication Date |
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| CN106470022A true CN106470022A (en) | 2017-03-01 |
Family
ID=56688703
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CN201510502257.1A Withdrawn CN106470022A (en) | 2015-08-14 | 2015-08-14 | A kind of filter circuit and method |
Country Status (2)
| Country | Link |
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| CN (1) | CN106470022A (en) |
| WO (1) | WO2016131319A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017193877A1 (en) * | 2016-05-10 | 2017-11-16 | 深圳市中兴微电子技术有限公司 | Pulse density modulation switching circuit and method and storage medium |
| CN117459065A (en) * | 2023-12-26 | 2024-01-26 | 深圳市九天睿芯科技有限公司 | Method and device for converting PDM signal into PCM signal and electronic equipment |
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| US6470365B1 (en) * | 1999-08-23 | 2002-10-22 | Motorola, Inc. | Method and architecture for complex datapath decimation and channel filtering |
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| US6470365B1 (en) * | 1999-08-23 | 2002-10-22 | Motorola, Inc. | Method and architecture for complex datapath decimation and channel filtering |
| JP2002271431A (en) * | 2001-03-14 | 2002-09-20 | Hitachi Kokusai Electric Inc | Low-pass filter |
| CN102035503A (en) * | 2010-11-19 | 2011-04-27 | 钜泉光电科技(上海)股份有限公司 | Filtering device and filtering method of cascaded integral comb filter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2017193877A1 (en) * | 2016-05-10 | 2017-11-16 | 深圳市中兴微电子技术有限公司 | Pulse density modulation switching circuit and method and storage medium |
| CN107359868A (en) * | 2016-05-10 | 2017-11-17 | 深圳市中兴微电子技术有限公司 | Pulse density modulated change-over circuit and method |
| CN117459065A (en) * | 2023-12-26 | 2024-01-26 | 深圳市九天睿芯科技有限公司 | Method and device for converting PDM signal into PCM signal and electronic equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2016131319A1 (en) | 2016-08-25 |
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Application publication date: 20170301 |