CN207753691U - A kind of modified Anti-aliasing Filter Circuits - Google Patents

Abstract

The utility model belongs to wave filter technology field more particularly to a kind of modified Anti-aliasing Filter Circuits, including：First resistor, second resistance, 3rd resistor, the 4th resistance, 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, first capacitance, the second capacitance, third capacitance, 4th capacitance, the 5th capacitance, the 6th capacitance, 7th capacitance, the 8th capacitance, operation amplifier unit and circuit first node, second node, third node, fourth node；The utility model has the following advantages：1, circuit structure is simple, easily realizes.2, circuit adjustable gain.3, single circuit can add prime filter circuit to improve filter effect, and multiple circuits can cascade.4, after improving circuit, it can not only ensure that channel was flat, but also improve squareness factor.5, after being improved to difference negative feedback amplifier circuit by single-ended negative feedback amplifier circuit, because of circuit symmetrical, there is very strong inhibition null offset and inhibit the ability of noise and interference.

Description

A kind of modified Anti-aliasing Filter Circuits

Technical field

The utility model is related to wave filter technology fields, refer specifically to a kind of modified Anti-aliasing Filter Circuits.

Background technology

Filter be it is a kind of can make useful frequency signal by by inhibit the electronic device of unwanted frequency signal simultaneously, commonly use In signal processing, the AF panel etc. of data transmission.Squareness factor (KxdB ＜ 1) is characterization filter selectivity quality One parameter, it describes the filter steep that response curve changes near cutoff frequency, calculation formula KxdB= BWxdB/BW3dB, (X can be 40dB, 30dB, 20dB etc.).Filter order is more, and rectangular degree is higher --- i.e. and K is closer to ideal Value 1, manufacture difficulty are certainly also bigger.Under normal circumstances, frequency overlapped-resistable filter is low-pass filter in over-sampling system, is used The degree of very little will be reduced to by the aliasing frequency component in sampled signal.It is each to produce in high-end instrument field The core component and circuit of product suffer from the index of high request.The performance and index of filter determine the difficulty of follow-up signal processing Degree, the safety of data transmission and signal anti-interference ability, determine whole system performance and index to a certain extent.Existing Under modern high precision measurement requires, the frequency overlapped-resistable filter of the indexs such as high squareness factor is needed, therefore, filter is improved and is ending The steep of frequency response curve variation nearby, improving squareness factor becomes problem to be solved.

Utility model content

The multiple negative feedback filter of tradition is although simple in structure, but filter effect is undesirable, squareness factor very little, much The index request of high end filter is not achieved.In view of the above-mentioned problems, the utility model provides a kind of modified anti-aliasing filter electricity Road optimizes on the basis of multiple negative feedback filter, not only passband can be kept flat, but also intermediate zone is made to decline The gradient become very steep, the selecting frequency characteristic of filter improves.

In order to solve the above-mentioned technical problem, the technical solution adopted in the utility model is：A kind of modified anti-aliasing filter Circuit, including：First resistor, second resistance, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th Resistance, the first capacitance, the second capacitance, third capacitance, the 4th capacitance, the 5th capacitance, the 6th capacitance, the 7th capacitance, the 8th capacitance, Operation amplifier unit and circuit first node, second node, third node, fourth node；First resistor is serially connected in operation amplifier Between the output signal anode and first node of unit；Second resistance is serially connected between first node and second node；Third electricity Resistance is serially connected between first node and operation amplifier unit reverse input end；4th resistance is serially connected in third node and fourth node Between；5th resistance is serially connected between fourth node and operation amplifier unit positive input；6th resistance is serially connected in operation and puts Between the output signal negative terminal and fourth node of big unit；7th resistance is serially connected between second node and input signal negative terminal； 8th resistance is serially connected between third node and input signal anode.First capacitance series are in operation amplifier unit reverse input end Between the output signal anode of operation amplifier unit；Second capacitance series are between first node and fourth node；Third electricity Appearance is serially connected between operation amplifier unit positive input and the output signal negative terminal of operation amplifier unit；4th capacitance series exist Between second node and third node；5th capacitance series are between second node and ground terminal；6th capacitance series are in third Between node and ground terminal；7th capacitance series are between first node and ground terminal；8th capacitance series in fourth node and Between ground terminal.

As a kind of optimal technical scheme of the utility model, operation amplifier unit is the electricity for having high-amplification-factor to voltage Road unit.

As a kind of optimal technical scheme of the utility model, operation amplifier unit includes positive input, reverse input end, Output end and power end.

Increase the 7th capacitance, the 8th capacity earth, filter cutoff frequency in the multiple negative feedback filter circuit of tradition (decline to 3dB Frequency points) becomes smaller, and quality factor Q value becomes larger, at passband cut-off frequency gain become larger, frequency band curve steepening.

Increase in the multiple negative feedback filter circuit of tradition the 4th capacitance, the 5th capacitance, the 6th capacitance, the 7th resistance, 8th resistance, the partial circuit are equivalent to rc filter circuit, and intermediate zone and stop-band frequency are suppressed, and entire frequency band curve becomes Smoothly.

Complete utility model circuit includes above-mentioned two parts, can not only ensure that the passband of filtering curve was flat, but also Squareness factor is improved, intermediate zone curve becomes precipitous.

Increase level-one to multistage rc filter circuit in the signal input front end of the utility model circuit.This circuit can increase Strong filter effect, filtering curve are precipitous and smooth.

3, it is cascaded on the basis of foregoing circuit.This circuit can increase the steep at passband cut-off frequency, rectangle system Number higher, filtering selecting frequency characteristic are more preferable.

The utility model has the advantages that compared with prior art：

1, circuit structure is simple, easily realizes.

2, circuit adjustable gain.

3, single circuit can add prime filter circuit to improve filter effect, and multiple circuits can cascade.

4, after improving circuit, it can not only ensure that passband was flat, but also improve squareness factor.

5, after being improved to difference negative feedback amplifier circuit by single-ended negative feedback amplifier circuit, because of circuit symmetrical, have very The strong ability for inhibiting null offset and inhibiting noise and interference.

Description of the drawings

The utility model is described in more detail below in conjunction with the accompanying drawings.

Fig. 1 is the schematic diagram of the multiple negative-feedback low-pass filter circuit of tradition.

Fig. 2 is the schematic diagram of the multiple negative-feedback low-pass filter circuit of the utility model first embodiment.

Fig. 3 is the schematic diagram of the multiple negative-feedback low-pass filter circuit of the utility model second embodiment.

Fig. 4 is the schematic diagram of the multiple negative-feedback low-pass filter circuit of the utility model third embodiment.

Fig. 5 is the design sketch of the multiple negative-feedback low-pass filter circuit of tradition.

Fig. 6 is the design sketch of the low-pass filter circuit of the utility model first embodiment.

Figure label：U1, first order operational amplifier；V1, the input signal source with noise；C1, the first capacitance；C2, Two capacitances；C3, third capacitance；C4, the 4th capacitance；C5, the 5th capacitance；C6, the 6th capacitance；C7, the 7th capacitance；C8, the 8th electricity Hold；R1, first resistor；R2, second resistance；R3,3rd resistor；R4, the 4th resistance；R5, the 5th resistance；R6, the 6th resistance； R7, the 7th resistance；R8, the 8th resistance.

Specific implementation mode

It is new below in conjunction with this practicality to keep the purpose, technical scheme and advantage of the utility model embodiment clearer Attached drawing in type embodiment, the technical scheme in the utility model embodiment is clearly and completely described, it is clear that is retouched The embodiment stated is a part of the embodiment of the utility model, instead of all the embodiments；Based on the reality in the utility model Example is applied, the every other embodiment that those of ordinary skill in the art are obtained without creative efforts all belongs to In the range of the utility model protection.

In the multiple negative-feedback low-pass filtering embodiment of tradition as shown in Figure 1, resistance R3 and capacitance C1 form a product Device, R2 and C2 is divided to form a low-pass filter, resistance R1 and resistance R2 make single channel be in negative-feedback amplification characteristic.

As shown in figure 5, for the amplitude-frequency response measured drawing of the multiple negative-feedback low-pass filter circuit of tradition, the frequency in passband Response curve is flat, does not rise and fall, and is then gradually reduced in suppressed frequency band.Filter effect is less desirable, squareness factor very little, mistake Band is crossed to decline gently.

It is the first embodiment of the utility model as shown in Figure 2, the utility model circuit is to the multiple negative-feedback low pass of tradition Filter circuit is improved so that the filtering characteristic of whole filter circuit is more preferable.

As shown in fig. 6, for the amplitude-frequency response measured drawing of the first embodiment.

Comparing the frequency response curve of Fig. 5 and Fig. 6, (curve of top is the multiple negative-feedback low-pass filter circuit of tradition in figure Frequency response curve, the curve of lower section is the amplitude-versus-frequency curve of improved multiple negative-feedback low-pass filter circuit), with filter On the basis of wave passband point 100KHz, decay to 8.66dB, 3dB of the multiple negative-feedback low-pass filter circuit of tradition in 1MHz Frequency points Bandwidth 550KHz or so, 20dB bandwidth 1950KHz or so；Improved multiple the first embodiment of negative-feedback low-pass filter circuit 31dB, three dB bandwidth 200KHz or so, 20dB bandwidth 650KHz or so are decayed in 1MHz Frequency points.Frequency in passband is rung Answer curve that passband can be kept flat, the gradient that intermediate zone declines becomes very steep again, and the selecting frequency characteristic of filter improves.

It is the second embodiment of the utility model as shown in Figure 3, adds multi-stage filter circuit again before differential signal input (circuit that the 8th resistance, the 9th resistance, the 9th capacitance, the tenth capacitance, the 11st capacitance form in figure is the filter for only having added level-one Wave circuit).Compared with the first embodiment, the program improves squareness factor, filter effect under the premise of keeping flatness More preferably.

It is the utility model third embodiment as shown in Figure 4, is cascaded using the circuit of the second embodiment.With Two embodiments are compared, and cascade circuit has higher squareness factor, the gradient of decline steeper.

The utility model optimizes on the basis of multiple negative feedback filter, can both keep flat, transition Become very steep again with the gradient declined, the selecting frequency characteristic of filter improves.

Finally it should be noted that：The above various embodiments is only to illustrate the technical solution of the utility model, rather than limits it System；Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should Understand：It still can be with technical scheme described in the above embodiments is modified, either to which part or whole Technical characteristic carries out equivalent replacement；And these modifications or replacements, this practicality that it does not separate the essence of the corresponding technical solution are new The range of each embodiment technical solution of type.

Claims (3)

1. a kind of modified Anti-aliasing Filter Circuits, which is characterized in that including：First resistor, second resistance, 3rd resistor, the Four resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the first capacitance, the second capacitance, third capacitance, the 4th electricity Hold, the 5th capacitance, the 6th capacitance, the 7th capacitance, the 8th capacitance, operation amplifier unit and circuit first node, second node, the Three nodes, fourth node；First resistor is serially connected between the output signal anode of operation amplifier unit and first node；Second electricity Resistance is serially connected between first node and second node；3rd resistor is serially connected in first node and operation amplifier unit reverse input end Between；4th resistance is serially connected between third node and fourth node；5th resistance is serially connected in fourth node and operation amplifier list Between first positive input；6th resistance is serially connected between the output signal negative terminal of operation amplifier unit and fourth node；7th Resistance is serially connected between second node and input signal negative terminal；8th resistance be serially connected in third node and input signal anode it Between, the first capacitance series are between operation amplifier unit reverse input end and the output signal anode of operation amplifier unit；Second Capacitance series are between first node and fourth node；Third capacitance series are put in operation amplifier unit positive input and operation Between the output signal negative terminal of big unit；4th capacitance series are between second node and third node；5th capacitance series exist Between second node and ground terminal；6th capacitance series are between third node and ground terminal；7th capacitance series are in first segment Between point and ground terminal；8th capacitance series are between fourth node and ground terminal.

2. a kind of modified Anti-aliasing Filter Circuits according to claim 1, which is characterized in that the operation amplifier unit To have the circuit unit of high-amplification-factor to voltage.

3. a kind of modified Anti-aliasing Filter Circuits according to claim 2, which is characterized in that the operation amplifier unit Including positive input, reverse input end, output end and power end.