CN104022746A - Operational amplifier circuit with fixed bandwidth and real-time variable gain - Google Patents

Operational amplifier circuit with fixed bandwidth and real-time variable gain Download PDF

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Publication number
CN104022746A
CN104022746A CN201410280972.0A CN201410280972A CN104022746A CN 104022746 A CN104022746 A CN 104022746A CN 201410280972 A CN201410280972 A CN 201410280972A CN 104022746 A CN104022746 A CN 104022746A
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pin
chip
max4907
resistance
unit
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CN201410280972.0A
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CN104022746B (en
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李德和
史振国
张永臣
张凯
王建强
何春芝
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Northeast Part Of China Weihai Optoelectronic Information Technical Concern Co
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Northeast Part Of China Weihai Optoelectronic Information Technical Concern Co
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Abstract

The invention relates to an operational amplifier circuit with fixed bandwidth and real-time variable gain, for solving the technical problems that the bandwidth of a conventional programmable amplifier varies along with variation of the grain and the response time is too long before and after the grain variation. The operational amplifier circuit comprises an operational amplifier, a fixed grain unit, a variable resistance unit, a fixed resistance unit and a control pulse input signal unit, wherein the operational amplifier is provided with an IN- pin, an IN+ pin, a Vs- pin, a Vout pin and a VVs+ pin; the IN- pin and the Vout pin are connected with the variable resistance unit; the control pulse input signal unit is connected with the IN- pin; the fixed grain unit is connected with the IN+ pin; the fixed grain circuit consists of resistors; the variable resistance unit consists of resistors and a switch device; the fixed resistance circuit consists of resistors; the control pulse input signal unit consists of a switch device. The operational amplifier circuit is widely applied to operational amplifier circuits.

Description

The discharge circuit of the real-time variable gain of a kind of fixed-bandwidth
Technical field
The present invention relates to a kind of discharge circuit, especially relate to the discharge circuit of the real-time variable gain of a kind of fixed-bandwidth.
Background technology
Programmable amplifier, as a kind of amplifier of gain-variable, is widely used in each field such as industrial production, scientific research.At present, programmable amplifier exist bandwidth with gain change change, gain change front and back long problem of response time.
Summary of the invention
The present invention be exactly for solve existing programmable amplifier bandwidth with gain change change, gain change front and back long technical problem of response time, provide one to control in real time gain, the discharge circuit of the real-time variable gain of fixed-bandwidth of identical system bandwidth is provided simultaneously.
The discharge circuit of the real-time variable gain of fixed-bandwidth provided by the invention, comprise operational amplifier, fixed gain unit, variable resistor unit, fixed resistance unit and control impuls input signal unit, operational amplifier is provided with IN-pin, IN+ pin, Vs-pin, Vout pin and Vs +pin, connects by variable resistor unit between IN-pin and Vout pin, and control impuls input signal unit is connected with IN-pin, and fixed gain unit is connected with IN+ pin; Fixed gain circuit is made up of resistor, and variable resistor unit is made up of resistor and switching device, and constant-resistance circuit is made up of resistor, and control impuls input signal unit is made up of switching device.
Preferably, operational amplifier is that THS4304 chip, switching device comprise a MAX4907 chip and the 2nd MAX4907 chip, and THS4304 chip is provided with IN-pin, IN+ pin, Vs-pin and Vout pin, the one MAX4907 chip and the 2nd MAX4907 chip are respectively equipped with SHDN pin, GND pin, COM1 pin, COM2 pin, IN pin, V+ pin, NO1 pin and NO2 pin, the SHDN pin of the one MAX4907 chip, GND pin and COM1 pin link together, the SHDN pin of described the 2nd MAX4907 chip, GND pin and COM1 pin link together, the COM2 pin of the one MAX4907 chip is connected with the 4th resistance, the COM2 pin of the 2nd MAX4907 chip is connected with the 6th resistance, after being connected with the NO2 pin of the 2nd MAX4907 chip, the NO2 pin of the one MAX4907 chip is connected with the 3rd resistance, the IN pin of the one MAX4907 chip is the first control end, the IN pin of the 2nd MAX4907 chip is the second control end,
The first resistance is connected with the IN+ pin of the 3rd resistance and THS4304 chip respectively, the NO1 pin of the one MAX4907 chip is connected with the IN-pin of THS4304 chip by the 5th resistance, the NO1 pin of the 2nd MAX4907 chip is connected with the IN-pin of THS4304 chip by the 7th resistance, the IN-pin of THS4304 chip is connected with the second resistance, between the IN-pin of THS4304 chip U1 and Vout pin, connects by variable resistor.
The invention has the beneficial effects as follows, realize the real-time control to gain, identical system bandwidth is provided simultaneously.Adopt steady noise gain to realize fixing system bandwidth, adopt switching device to realize resistance adjustment, utilize electric resistance partial pressure to realize the decay control to input signal, realize the gain control to input signal by the fixed gain of amplifier.Adopt the switching device of ns level response speed, realize the real-time controlled adjustment of gain.Meanwhile, this invention system configuration is simple, and cost is low, is convenient to control.
Further aspect of the present invention, by the description of following embodiment, is clearly recorded.
Brief description of the drawings
Fig. 1 is theory diagram of the present invention;
Fig. 2 is circuit theory diagrams of the present invention.
Reference numeral explanation:
1. operational amplifier; 2. fixed gain unit; 3. variable resistor unit; 4. fixed resistance unit; 5. control impuls input signal unit; 6. voltage input signal unit; R1, R2, R3, R4, R5, R6, R7 are respectively the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance; Rf is variable resistor; U1 is THS4304 chip, and THS4304 chip is provided with the 2nd pin, the 3rd pin, the 4th pin, the 6th pin, the 7th pin and the 8th pin; U2 is a MAX4907 chip, and a MAX4907 chip is provided with SHDN pin, GND pin, COM1 pin, COM2 pin, IN pin, V+ pin, NO1 pin and NO2 pin; U3 is the 2nd MAX4907 chip, and the 2nd MAX4907 chip is provided with SHDN pin, GND pin, COM1 pin, COM2 pin, IN pin, V+ pin, NO1 pin and NO2 pin; VCC is power supply; Input is input signal, and Output is output signal, and Control_1 is the first control signal, and Control_2 is the second control signal.
Embodiment
Referring to accompanying drawing, with specific embodiment, the present invention is described in further detail.
As shown in Figure 1, the present invention includes operational amplifier 1, fixed gain unit 2, variable resistor unit 3, fixed resistance unit 4, control impuls input signal unit 5 and voltage input signal unit 6, fixed gain circuit 2 is made up of resistor, variable resistor unit 3 is made up of resistor and switching device, constant-resistance circuit 4 is made up of resistor, control impuls input signal unit 5 is the input of switching device control signal, and voltage input signal 6 is circuit input signal.
Operational amplifier 1 is provided with IN-pin, IN+ pin, Vs-pin, Vout pin and Vs +pin, connects by variable resistor unit 3 between IN-pin and Vout pin, and control impuls input signal unit 5 is connected with IN-pin, and fixed gain unit 2 is connected with IN+ pin.
As shown in Figure 2, adopt the circuit of THS4304 chip as switching device.It comprises THS4304 chip U1, a MAX4907 chip U2 and the 2nd MAX4907 chip U3, and the 2nd pin of THS4304 chip, the 3rd pin, the 4th pin, the 6th pin, the 7th pin are respectively IN-pin, IN+ pin, Vs-pin, Vout pin, Vs +pin.SHDN pin, GND pin and the equal ground connection of COM1 pin of the one MAX4907 chip U2, SHDN pin, GND pin and the equal ground connection of COM1 pin of the 2nd MAX4907 chip U3, the COM2 pin of the one MAX4907 chip U2 is connected with input signal Input by the 4th resistance R 4, and the COM2 pin of the 2nd MAX4907 chip U3 is connected with input signal Input by the 6th resistance R 6.After the NO2 pin of the one MAX4907 chip U2 is connected with the NO2 pin of the 2nd MAX4907 chip U3, by the 3rd resistance R 3 ground connection, the V+ pin of a MAX4907 chip U2 meets power supply VCC, and the V+ pin of the 2nd MAX4907 chip U3 meets power supply VCC.
The first control signal Control_1 is connected with the IN pin of a MAX4907 chip U2, and the second control signal Control_2 is connected with the IN pin of the 2nd MAX4907 chip U3.
Input signal Input is connected with first resistance R 1 one end, and the other end of the first resistance R 1 divides two-way, and the 3rd pin of a road and THS4304 chip U1 is connected, and another road is connected with the 3rd resistance R 3.The NO1 pin of the one MAX4907 chip U2 is connected with the 2nd pin of THS4304 chip U1 by the 5th resistance R 5, the NO1 pin of the 2nd MAX4907 chip U3 is connected with the 2nd pin of THS4304 chip U1 by the 7th resistance R 7, and the 2nd pin of THS4304 chip U1 is simultaneously by the second resistance R 2 ground connection.The 4th pin ground connection of THS4304 chip U1, the 7th pin of THS4304 chip U1 meets power supply VCC, between the 2nd pin of THS4304 chip U1 and the 6th pin, connects by variable resistor Rf, and the 6th pin of THS4304 chip U1 is output signal Output.
Power supply VCC is 3.3v, and this operational amplifier U1 is THS4304 chip, and MAX4907 chip belongs to switching device.
The second resistance R 2 and the variable resistor Rf of the circuit in above-mentioned Fig. 2 have formed fixed gain unit, the first resistance R 1, the 4th resistance R 4, the 6th resistance R 6, a MAX4907 chip U2 and the 2nd MAX4907 chip U3 have formed variable resistor unit, the 3rd resistance R 3 has formed alone fixed resistance unit, the 5th resistance R 5, the 7th resistance R 7, a MAX4907 chip U2 and the 2nd MAX4907 chip U3 form the matching network of variable resistor unit jointly, variable resistor unit and fixed resistance cell formation adjustable damping circuit, realized the gain control to signal.
When work, whether conducting by control signal control switch device channel, realize setting to variable resistor cell resistance, by the adjustable damping circuit of variable resistor unit and fixed resistance cell formation, to signal controls that decay, and then realization is to the control gaining.The one MAX4907 chip U2 and the 2nd MAX4907 chip U3 conducting and cut-off under the control of the first control signal and the second control signal, totally four kinds of compound modes, have realized 4 grades of adjustable gain controls.The second resistance R 2 and variable resistor Rf have formed fixed gain circuit, have realized fixing noise gain, and its value, for (1+Rf/R2), has realized fixing system bandwidth thus.The one MAX4907 chip U2 and the 2nd MAX4907 chip U3 have ns level response speed to control signal, have realized the real-time controlled adjustment to gain.
If, Rf=R1, R2=R3, Rf=10R2, output signal Output is Vo, and input signal Input is Vin, and Control_1 and Control_2 are control signal, in the time being 0, represent the cut-off of switch opens passage; In the time being 1, represent that switch closing passage connects.
Have:
V o = V in · R 3 R 3 + R 1 / / C 1 · R 4 / / C 3 · R 6 · ( 1 + R f R 2 / / C 1 · R 5 / / C 2 · R 4 ) - - - ( 1 )
Wherein:
Work as R 5//R 7> > R 2time, R 2//C 2r 5//C 2r 7≈ R 2, above formula (1) can be equivalent to following formula:
V o = V in · R 3 R 3 + R 1 / / C 1 · R 4 / / C 2 · R 6 · ( 1 + R f R 2 ) - - - ( 2 )
If R4=R5=20R2, R6=R7=30R2, has following relation according to formula (1):
Situation 1:Control_1=0, Control_2=0
V o = V in · R 3 R 3 + R 1 · ( 1 + R f R 2 ) = V in · R 2 R 2 + 10 R 2 · ( 1 + 10 R 2 R 2 ) = V in
Situation 2:Control_1=1, Control_2=0
V o = V in · R 3 R 3 + R 1 / / R 4 · ( 1 + R f R 2 ) = V in · R 2 R 2 + 10 R 2 / / 20 R 2 · ( 1 + 10 R 2 R 2 ) ≈ 1.43 V in
Situation 3:Control_1=0, Control_2=1
V o = V in · R 3 R 3 + R 1 / / R 6 · ( 1 + R f R 2 ) = V in · R 2 R 2 + 10 R 2 / / 30 R 2 · ( 1 + 10 R 2 R 2 ) ≈ 1.29 V in
Situation 4:Control_1=1, Control_2=1
V o = V in · R 2 R 3 + R 1 / / R 4 / / R 6 · ( 1 + R f R 2 ) = V in · R 2 R 2 + 10 R 2 / / 20 R 2 / / 30 R 2 · ( 1 + 10 R 2 R 2 ) ≈ 1.67 V in
According to above-mentioned resistance relation, realize the amplification to 1,1.29,1.43 and 1.67 times of input signals.This circuit can be revised sensitivity as required, realizes 4 kinds of different amplifications.Meanwhile, number that can expansion switch device, realizes a greater variety of amplifications.If the number of switching device used is n, can realize 2 n power kind amplification., if do not consider strict voltage imbalance, the build-out resistor of the 5th resistance R 5 and the 7th resistance R 7 can be removed meanwhile, realize at most 2 2n power kind amplification.
The above,, only to the preferred embodiments of the present invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various modifications and variations.Every in claim limited range of the present invention, any amendment of making, be equal to replacement, improvement etc., all should be within protection scope of the present invention.

Claims (2)

1. the discharge circuit of the real-time variable gain of fixed-bandwidth, it is characterized in that, comprise operational amplifier, fixed gain unit, variable resistor unit, fixed resistance unit and control impuls input signal unit, described operational amplifier is provided with IN-pin, IN+ pin, Vs-pin, Vout pin and Vs +pin, connects by described variable resistor unit between described IN-pin and described Vout pin, and described control impuls input signal unit is connected with described IN-pin, and described fixed gain unit is connected with described IN+ pin; Described fixed gain circuit is made up of resistor, and described variable resistor unit is made up of resistor and switching device, and described constant-resistance circuit is made up of resistor, and described control impuls input signal unit is made up of switching device.
2. the discharge circuit of the real-time variable gain of fixed-bandwidth according to claim 1, it is characterized in that, described operational amplifier is that THS4304 chip, described switching device comprise a MAX4907 chip and the 2nd MAX4907 chip, and described THS4304 chip is provided with IN-pin, IN+ pin, Vs-pin and Vout pin, a described MAX4907 chip and described the 2nd MAX4907 chip are respectively equipped with SHDN pin, GND pin, COM1 pin, COM2 pin, IN pin, V+ pin, NO1 pin and NO2 pin, the SHDN pin of a described MAX4907 chip, GND pin and COM1 pin link together, the SHDN pin of described the 2nd MAX4907 chip, GND pin and COM1 pin link together, the COM2 pin of a described MAX4907 chip is connected with the 4th resistance, the COM2 pin of described the 2nd MAX4907 chip is connected with the 6th resistance, after being connected with the NO2 pin of described the 2nd MAX4907 chip, the NO2 pin of a described MAX4907 chip is connected with the 3rd resistance, the IN pin of a described MAX4907 chip is the first control end, the IN pin of described the 2nd MAX4907 chip is the second control end,
The first resistance is connected with the IN+ pin of described the 3rd resistance and THS4304 chip respectively, the NO1 pin of a described MAX4907 chip is connected with the IN-pin of described THS4304 chip by the 5th resistance, the NO1 pin of described the 2nd MAX4907 chip is connected with the IN-pin of described THS4304 chip by the 7th resistance, the IN-pin of described THS4304 chip is connected with the second resistance, between the IN-pin of described THS4304 chip U1 and Vout pin, connects by variable resistor.
CN201410280972.0A 2014-06-20 2014-06-20 A kind of discharge circuit of fixed-bandwidth real-time variable gain Expired - Fee Related CN104022746B (en)

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Publication number Priority date Publication date Assignee Title
WO2001026218A1 (en) * 1999-10-06 2001-04-12 Tripath Technology Inc. Programmable gain feedback amplifier and method for maintaining constant phase
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CN102025325A (en) * 2009-09-11 2011-04-20 罗姆股份有限公司 Audio-frequency amplifier and electronic equipment using the same
CN103026619A (en) * 2010-07-26 2013-04-03 三星电子株式会社 Variable resister having resistance varying geometrically ratio and control method thereof
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