CN103441740B - A kind of small signals amplification circuit - Google Patents
A kind of small signals amplification circuit Download PDFInfo
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- CN103441740B CN103441740B CN201310383115.9A CN201310383115A CN103441740B CN 103441740 B CN103441740 B CN 103441740B CN 201310383115 A CN201310383115 A CN 201310383115A CN 103441740 B CN103441740 B CN 103441740B
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Abstract
The invention provides a kind of small signals amplification circuit, by connecting with resistance R3 between the output and an input of closed loop output stage operational amplifier U2 of open loop input stage operational amplifier U1, the internal feedback ring of closed loop output stage operational amplifier U2 is connected with electric capacity C1 and resistance R4, connected by resistance R2 between one input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 of the input end of open loop input stage operational amplifier U1, the other end ground connection of resistance R1 or connect this connected mode of input of this small signals amplification circuit, make this small signals amplification circuit integrity closed loop gain only relevant with resistance R2 with resistance R1.For certain useful signal close to noise, i.e. weak signal, as long as signal frequency exists
within, use small signals amplification circuit of the present invention, can both extract totally, useful signal clearly.
Description
Technical field
The present invention relates to amplifying circuit technical field, particularly relate to a kind of small signals amplification circuit.
Background technology
The amplifying circuit formed after amplifier cascade, its overall gain amplifier is more much higher than the gain amplifier of the amplifying circuit be made up of an amplifier.
Amplifying circuit 10 as shown in Figure 1, it comprises an amplifier U1, and the feedback resistance of amplifier U1 is R2, the input signal of amplifying circuit 10 is ei, output signal is connected to the inverting input of amplifier U1 for eo, input signal ei by resistance R1, the positive input end grounding of amplifier U1.So, the gain of amplifying circuit 10
=
, wherein,
for the gain of amplifying circuit 10, we claim this gain to be the closed loop gain of amplifying circuit usually, in order to distinguish the open-loop gain A of amplifier U1 self.
=β, β are the feedback factor of amplifying circuit.
We indicate gain and the bandwidth of amplifying circuit usually by logarithmic coordinates.Be illustrated in figure 2 the curve of amplifier open-loop gain A, abscissa line is frequency range point corresponding to bandwidth, and the longitudinal axis is gain.So open-loop gain A=j of amplifier
, wherein
for the noise gain in other words of the noise frequency in input signal.
Fig. 3 is the reciprocal curve of feedback factor β.So, the gain of amplifying circuit 10
=
=
, its curve as shown in Figure 4.By A
cLcurve can be found out, at curve break
before
plateau, its numerical value no better than
, between this signal amplification region that namely amplifier normally uses.This interval can be similar to be thought
=
.Breakover point
afterwards, the decay of 20dB/10 octave is pressed in the gain of amplifying circuit.
Traditionally, we use A
cLcurve decays to the Frequency point at-3dB place to define the bandwidth of this amplifying circuit 10.-3dB point namely
curve drops to
time Frequency point, namely
time Frequency point.
By formula
=
the mould of closed loop gain can be derived
=
.To make
drop to
, above formula need meet
=
.This condition only exists
=
in time, just sets up, and therefore this place's Frequency point is exactly-three dB bandwidth.
In Fig. 4, curve
with curve
equal position is exactly the crosspoint of these two curves
,
for the useful signal bandwidth of this amplifying circuit.We can obtain as drawn a conclusion thus: the signal bandwidth of amplifying circuit 10 is exactly
curve with
the frequency at the crosspoint place of curve.
The closed loop gain A of amplifying circuit 10 is improved if want
cL, just must reduce feedback factor β, will
curve moves up.As shown in Figure 5,
after curve moves up, its noise bandwidth
almost do not change, but the useful signal bandwidth of this amplifying circuit
can be reduced to
, cause the dedicated bandwidth that has of this amplifying circuit to decline a lot, and the size of noise bandwidth does not really change.
In order to improve the gain of amplifying circuit, multiple amplifier is carried out cascade by usually, as shown in Figure 5.Amplifying circuit 20 shown in Fig. 6, it comprises amplifier U1 and U2 of two cascades, the feedback resistance of amplifier U1 is R2, the feedback resistance of amplifier U2 is R4, the input signal of overall amplifying circuit is ei, output signal is eo, input signal ei is connected to the inverting input of amplifier U1 by resistance R1, the positive input end grounding of amplifier U1, the output of amplifier U1 is connected to the inverting input of amplifier U2 by resistance R3, the positive input end grounding of amplifier U2, the output of amplifier U2 is directly connected with the output of overall amplifying circuit.The gain that this amplifying circuit is total
=
=
, wherein,
for the gain that overall amplifying circuit is total,
with
the one pass gain of amplifier U1 and amplifier U2 respectively,
with
the single-stage feedback factor of amplifier U1 and amplifier U2 respectively.So, in the figure 7, we can see feedback profile
with gain curve
crosspoint frequency
, i.e. the useful signal bandwidth of this amplifying circuit 20
with single-stage amplifying circuit
crosspoint frequency identical, that is, under the prerequisite improving circuit overall gain, the useful signal bandwidth of this amplifying circuit 20
constant.Visible, the amplifying circuit after multiple amplifier cascade, which raises the gain amplifier of amplifying circuit and bandwidth does not really reduce.
But in the amplifying circuit 20 after multiple amplifier cascade, it in raising useful signal multiplication factor simultaneously, also improve the multiplication factor of noise, its signal to noise ratio does not improve, and for the weak signal close to noise, what it obtained after amplifying is the noise that amplitude is larger.That is, although useful signal has been exaggerated, be also exaggerated by noise, signal after amplifying still is difficult to useful signal and noise signal to distinguish simultaneously.
Summary of the invention
For this reason, technical problem to be solved by this invention is: provide a kind of small signals amplification circuit, and make while raising signal amplification factor, the bandwidth of all right compression noise, so that separate weak signal from noise.
So, the invention provides a kind of small signals amplification circuit, comprise: open loop input stage operational amplifier U1 and closed loop output stage operational amplifier U2, it is characterized in that, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with an input of closed loop output stage operational amplifier U2, the internal feedback ring of closed loop output stage operational amplifier U2 is connected with the electric capacity C1 and resistance R4 that are one another in series, connected by resistance R2 between one input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 of the input end of open loop input stage operational amplifier U1, the other end ground connection of resistance R1 or connect the input of this small signals amplification circuit, if other one end ground connection of resistance R1, an other input of then open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit, if the other end of resistance R1 connects the input of this small signals amplification circuit, an other input end grounding of then open loop input stage operational amplifier U1, the output of this small signals amplification circuit is connected with the output of closed loop output stage operational amplifier U2.
Wherein, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the inverting input of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the output of this inverting input and closed loop output stage operational amplifier U2, the positive input end grounding of closed loop output stage operational amplifier U2, connected by resistance R2 between the normal phase input end of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the normal phase input end place of open loop input stage operational amplifier U1, other one end ground connection of resistance R1, the inverting input of open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit.
Preferably, resistance R1 value is 0 ~ 10K Ω, and resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value be 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 1000pF ~ 0.1uF.
Best value: resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uf.
Or, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the inverting input of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the output of this inverting input and closed loop output stage operational amplifier U2, the positive input end grounding of closed loop output stage operational amplifier U2, connected by resistance R2 between the normal phase input end of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the normal phase input end place of open loop input stage operational amplifier U1, other one end of resistance R1 connects the input of this small signals amplification circuit, the reverse inter-input-ing ending grounding of open loop input stage operational amplifier U1.
Preferably, resistance R1 value is 0 ~ 10K Ω, and resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value be 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 1000pF ~ 0.1uF.
Best value: resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uf.
Or, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the normal phase input end of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the inverting input of closed loop output stage operational amplifier U2 and its output, this inverting input is also by resistance R5 ground connection, connected by resistance R2 between the inverting input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the inverting input place of open loop input stage operational amplifier U1, other one end of resistance R1 connects the input of this small signals amplification circuit, the positive input end grounding of open loop input stage operational amplifier U1.
Preferably, resistance R1 value is 0 ~ 10K Ω, and resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value be 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 1000pF ~ 0.1uF, and resistance R5 value is 1K Ω ~ 100K Ω.
Best value: resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uf, and resistance R5 value is 10K Ω.
Small signals amplification circuit of the present invention, by connecting with resistance R3 between the output and an input of closed loop output stage operational amplifier U2 of open loop input stage operational amplifier U1, the internal feedback ring of closed loop output stage operational amplifier U2 is connected with the electric capacity C1 and resistance R4 that are one another in series, connected by resistance R2 between one input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 of the input end of open loop input stage operational amplifier U1, the other end ground connection of resistance R1 or connect the input of this small signals amplification circuit, if other one end ground connection of resistance R1, an other input of then open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit, if the other end of resistance R1 connects the input of this small signals amplification circuit, this connected mode of an other input end grounding of then open loop input stage operational amplifier U1, make this small signals amplification circuit integrity closed loop gain only relevant with resistance R2 with resistance R1, resistance R3, resistance R4, resistance R5 and electric capacity C1 only changes the overall open-loop gain of this small signals amplification circuit.For certain useful signal close to noise, i.e. weak signal, as long as signal frequency exists
within, use small signals amplification circuit of the present invention, can both extract totally, useful signal clearly.The amplifying circuit overcome because of equivalent amount operational amplifier cascade composition can only by useful signal and noise signal impartial amplification and cannot extract the drawback of useful signal simultaneously.
Accompanying drawing explanation
Fig. 1 is an amplification circuit structure schematic diagram of the prior art;
Fig. 2 is the logarithmic plot of the open-loop gain of amplifying circuit shown in Fig. 1;
Fig. 3 is the logarithmic plot of the feedback factor of amplifying circuit shown in Fig. 1;
Fig. 4 is the logarithmic plot of the closed loop gain of amplifying circuit shown in Fig. 1;
Fig. 5 is the logarithmic plot of useful signal bandwidth sum noise bandwidth contrast after the raising of amplifying circuit shown in Fig. 1 closed loop gain;
Fig. 6 is another amplification circuit structure schematic diagram of the prior art;
Fig. 7 is the closed loop gain of amplifying circuit shown in Fig. 6
contrast logarithmic plot;
Fig. 8 is small signals amplification electrical block diagram described in the embodiment of the present invention one;
Fig. 9 is small signals amplification electrical block diagram described in the embodiment of the present invention two;
Figure 10 is small signals amplification electrical block diagram described in the embodiment of the present invention three;
The open-loop gain that Figure 11 is small signals amplification circuit acquisition described in the embodiment of the present invention and the logarithmic plot of common multistage amplifier circuits open-loop gain contrast;
The closed loop gain that Figure 12 is small signals amplification circuit acquisition described in the embodiment of the present invention and the logarithmic plot of common multistage amplifier circuits closed loop gain contrast.
Embodiment
Below, describe the present invention by reference to the accompanying drawings.
Embodiment one
As shown in Figure 8, present embodiments provide a kind of small signals amplification circuit, this amplifying circuit comprises: open loop input stage operational amplifier U1 and closed loop output stage operational amplifier U2, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the inverting input of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the output of this inverting input and closed loop output stage operational amplifier U2, the positive input end grounding of closed loop output stage operational amplifier U2, connected by resistance R2 between the normal phase input end of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the normal phase input end place of open loop input stage operational amplifier U1, other one end ground connection of resistance R1, the inverting input of open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit.
Wherein, resistance R1 value is 0 ~ 10K Ω, and resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value be 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 1000pF ~ 0.1uF.
Best value: resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uf.
Embodiment two
As shown in Figure 9, present embodiments provide a kind of small signals amplification circuit, this amplifying circuit comprises: open loop input stage operational amplifier U1 and closed loop output stage operational amplifier U2, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the inverting input of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the output of this inverting input and closed loop output stage operational amplifier U2, the positive input end grounding of closed loop output stage operational amplifier U2, connected by resistance R2 between the normal phase input end of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the normal phase input end place of open loop input stage operational amplifier U1, other one end of resistance R1 connects the input of this small signals amplification circuit, the reverse inter-input-ing ending grounding of open loop input stage operational amplifier U1.
Wherein, resistance R1 value is 0 ~ 10K Ω, and resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value be 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 1000pF ~ 0.1uF.
Best value: resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uf.
Embodiment three
As shown in Figure 10, present embodiments provide a kind of small signals amplification circuit, this amplifying circuit comprises: open loop input stage operational amplifier U1 and closed loop output stage operational amplifier U2, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the normal phase input end of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the inverting input of closed loop output stage operational amplifier U2 and its output, this inverting input is also by resistance R5 ground connection, connected by resistance R2 between the inverting input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the inverting input place of open loop input stage operational amplifier U1, other one end of resistance R1 connects the input of this small signals amplification circuit, the positive input end grounding of open loop input stage operational amplifier U1.
Wherein, resistance R1 value is 0 ~ 10K Ω, and resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value be 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 1000pF ~ 0.1uF, and resistance R5 value is 1K Ω ~ 100K Ω.
Best value: resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uf, and resistance R5 value is 10K Ω.
By circuit connecting relation described in above-mentioned three embodiments, we can find out: two operational amplifiers in small signals amplification circuit described in the present embodiment are not the connected modes adopting the cascade of normal operation amplifier, but input stage operational amplifier U1 open loop, output stage operational amplifier U2 carries internal feedback ring, i.e. output stage operational amplifier U2 closed loop.Open loop input stage operational amplifier U1 and closed loop output stage operational amplifier U2 can be equivalent to an independently operational amplifier U, and only the open-loop gain of this operation independent amplifier is higher than the open-loop gain of the amplifying circuit only comprising an operational amplifier.
According to the derivation formula described in background technology, the overall closed loop gain of small signals amplification circuit described in above-mentioned three embodiments is
=
=R2/R1, visible and resistance R3, resistance R4, resistance R5 and electric capacity C1 have nothing to do.Resistance R3, resistance R4, resistance R5 and electric capacity C1 just change the open-loop gain of equivalent operation independent amplifier U
.
But, the introducing of electric capacity C1, make again the overall open-loop gain of small signals amplification circuit described in above-mentioned three embodiments show some is unusual, suppose that the open-loop gain of the operational amplifier of two common cascades is A, described in above-mentioned three embodiments, the overall open-loop gain of small signals amplification circuit is
, then open-loop gain A and open-loop gain are
logarithmic coordinates as shown in figure 11, its intersection point fc and fc` is on the horizontal scale the noise bandwidth cut-off frequency point in amplifying circuit.
As seen in Figure 11: in low-frequency range, due to the existence of C1, closed loop output stage operational amplifier U2 is made to be equivalent to open loop, now described small signals amplification circuit integrity open-loop gain
identical with the amplifying circuit open-loop gain A of the operational amplifier of two common cascades, in this low-frequency range, useful signal is able to enough amplifications.Along with frequency increases gradually, electric capacity C1 impedance reduces, the closed loop gain of closed loop output stage operational amplifier U2 declines rapidly under the effect of inner feedback loop, causes the open-loop gain cut-off frequency point fc` of equivalent operation independent amplifier U greatly to shift to an earlier date than the amplifying circuit open-loop gain cut-off frequency point fc of the operational amplifier of two common cascades.This means that noise bandwidth greatly reduces.
So, along with frequency increases gradually, how does useful signal change again? as shown in figure 12, from the overall closed loop gain of small signals amplification circuit described in above-mentioned three embodiments | the amplifying circuit closed loop gain of the operational amplifier of Acl'| curve and two common cascades | Acl| curve draws: the useful signal bandwidth cut-off frequency of small signals amplification circuit described in above-mentioned three embodiments
than the useful signal bandwidth cut-off frequency of the operational amplifier of two common cascades
also reduced, but as can be seen from the figure, the noise bandwidth that is far from that useful signal bandwidth declines declines many.Consider it is the cause of logarithmic coordinates, if logarithmic coordinates are converted into linear coordinate, so noise bandwidth declines general more than 10 times, and useful signal bandwidth declines within 3 times.
Therefore, for certain useful signal close to noise, i.e. weak signal, as long as signal frequency exists
within, use three small signals amplification circuit described in the present embodiment, can both extract totally, useful signal clearly.The amplifying circuit overcome because of equivalent amount operational amplifier cascade composition can only by useful signal and noise signal impartial amplification and cannot extract the drawback of useful signal simultaneously.
In sum, small signals amplification circuit of the present invention, by connecting with resistance R3 between the output and an input of closed loop output stage operational amplifier U2 of open loop input stage operational amplifier U1, the internal feedback ring of closed loop output stage operational amplifier U2 is connected with the electric capacity C1 and resistance R4 that are one another in series, connected by resistance R2 between one input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 of the input end of open loop input stage operational amplifier U1, the other end ground connection of resistance R1 or connect the input of this small signals amplification circuit, if other one end ground connection of resistance R1, an other input of then open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit, if the other end of resistance R1 connects the input of this small signals amplification circuit, this connected mode of an other input end grounding of then open loop input stage operational amplifier U1, make this small signals amplification circuit integrity closed loop gain only relevant with resistance R2 with resistance R1, resistance R3, resistance R4, resistance R5 and electric capacity C1 only changes the overall open-loop gain of this small signals amplification circuit.For certain useful signal close to noise, i.e. weak signal, as long as signal frequency exists
within, use three small signals amplification circuit described in the present embodiment, can both extract totally, useful signal clearly.The amplifying circuit overcome because of equivalent amount operational amplifier cascade composition can only by useful signal and noise signal impartial amplification and cannot extract the drawback of useful signal simultaneously.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a small signals amplification circuit, comprise: open loop input stage operational amplifier U1 and closed loop output stage operational amplifier U2, it is characterized in that, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with an input of closed loop output stage operational amplifier U2, the internal feedback ring of closed loop output stage operational amplifier U2 is connected with the electric capacity C1 and resistance R4 that are one another in series, connected by resistance R2 between one input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 of the input end of open loop input stage operational amplifier U1, the other end ground connection of resistance R1 or connect the input of this small signals amplification circuit, if other one end ground connection of resistance R1, an other input of then open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit, if the other end of resistance R1 connects the input of this small signals amplification circuit, an other input end grounding of then open loop input stage operational amplifier U1, the output of this small signals amplification circuit is connected with the output of closed loop output stage operational amplifier U2.
2. small signals amplification circuit according to claim 1, it is characterized in that, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the inverting input of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the output of this inverting input and closed loop output stage operational amplifier U2, the positive input end grounding of closed loop output stage operational amplifier U2, connected by resistance R2 between the normal phase input end of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the normal phase input end place of open loop input stage operational amplifier U1, other one end ground connection of resistance R1, the inverting input of open loop input stage operational amplifier U1 is connected with the input of this small signals amplification circuit.
3. small signals amplification circuit according to claim 2, is characterized in that, resistance R1 value is 0 ~ 10K Ω, resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value is 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 0.001uF ~ 0.1uF.
4. small signals amplification circuit according to claim 3, is characterized in that, resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uF.
5. small signals amplification circuit according to claim 1, it is characterized in that, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the inverting input of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the output of this inverting input and closed loop output stage operational amplifier U2, the positive input end grounding of closed loop output stage operational amplifier U2, connected by resistance R2 between the normal phase input end of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the normal phase input end place of open loop input stage operational amplifier U1, other one end of resistance R1 connects the input of this small signals amplification circuit, the reverse inter-input-ing ending grounding of open loop input stage operational amplifier U1.
6. small signals amplification circuit according to claim 5, is characterized in that, resistance R1 value is 0 ~ 10K Ω, resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value is 1K Ω ~ 100K Ω, resistance R4 value be 1K Ω ~ 100K Ω, electric capacity C1 value is 0.001uF ~ 0.1uF.
7. small signals amplification circuit according to claim 6, is characterized in that, resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uF.
8. small signals amplification circuit according to claim 1, it is characterized in that, the output of open loop input stage operational amplifier U1 is connected by resistance R3 with the normal phase input end of closed loop output stage operational amplifier U2, the electric capacity C1 and resistance R4 that are one another in series is connected with between the inverting input of closed loop output stage operational amplifier U2 and its output, this inverting input is also by resistance R5 ground connection, connected by resistance R2 between the inverting input of open loop input stage operational amplifier U1 and the output of closed loop output stage operational amplifier U2, resistance R2 is in one end of the contact contact resistance R1 at the inverting input place of open loop input stage operational amplifier U1, other one end of resistance R1 connects the input of this small signals amplification circuit, the positive input end grounding of open loop input stage operational amplifier U1.
9. small signals amplification circuit according to claim 8, it is characterized in that, resistance R1 value is 0 ~ 10K Ω, resistance R2 value is 100K Ω ~ 10G Ω, resistance R3 value is 1K Ω ~ 100K Ω, resistance R4 value is 1K Ω ~ 100K Ω, electric capacity C1 value is 0.001uF ~ 0.1uF, and resistance R5 value is 1K Ω ~ 100K Ω.
10. small signals amplification circuit according to claim 9, is characterized in that, resistance R1 value is 1K Ω, and resistance R2 value is 10M Ω, and resistance R3 value is 10K Ω, and resistance R4 value is 1K Ω, and electric capacity C1 value is 0.047uF, and resistance R5 value is 10K Ω.
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| CN200970233Y (en) * | 2006-11-22 | 2007-11-07 | 李楚雅 | Filter for improving intracardiac electric physiological wave form while intracardiac electrode output stimulating |
| CN203399065U (en) * | 2013-08-28 | 2014-01-15 | 武汉矽感科技有限公司 | Weak signal amplification circuit |
Non-Patent Citations (2)
| Title |
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| 微弱信号检测的前置放大电路设计;张石锐 等;《微计算机信息》;20090823;第25卷(第8-2期);第223-224、188页 * |
| 近地层紫外自由空间通信微弱信号放大器设计;成中涛 等;《光电技术应用》;20120815;第27卷(第4期);第1-6 * |
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| CN103441740A (en) | 2013-12-11 |
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