Background technique
IC interior is frequently necessary to build an internal regulated voltage source unrelated with power supply.The internal electric source is sometimes
The purpose of isolation external power supply noise is realized as the inside low noise power supply of sensitive circuit, can also be used as voltage reduction module sometimes is
The conversion of high pressure to low pressure is realized in the power supply of internal low-voltage circuit.
As shown in Figure 1, regulated power supply is usually by band-gap reference, operational amplifier, power tube, feedback resistance group in traditional piece
At, in which: sensitive circuit of the bandgap reference voltage as piece inner core key considers for precision and antinoise, also usually hangs
Under the piece interior power.Such as in Mehrmanesh, S.and Vahidfar, M.B., " A 1-volt, high PSRR, CMOS
bandgap voltage reference",Circuits and Systems 2003.ISCAS’03.Proceedings
In circuit disclosed in ofthe 2003International Symposium on, vol.1, pp.I381-I384, May.2003.
Therefore one side bandgap reference voltage is powered dependent on piece interior power, and the voltage swing of piece interior power depends on band gap voltage
The output of benchmark, and then form mutually nested, complementary two feedback network.Wherein, the first feedback network is
Band-gap reference circuit is constituted, and the negative feedback mechanism of the network is closed for ratio needed for determining generation zero-temperature coefficient band gap voltage
System;Second feedback network is that regulated power supply generates loop, output electricity of the negative feedback mechanism of the network for trimmer interior power
Pressure is the scalar multiple of band gap voltage, and guarantees the constant of output voltage under the conditions of different loads.
Above-mentioned mutually nested, complementary topological structure, brings following Railway Project in actual use:
1, it is not easy to stablize, compensates complexity: as described above, this topological structure contains at least two negative feedback network, to protect
It demonstrate,proves whole system to stablize, needs to compensate two negative feedback networks respectively, guarantee each self-stabilization of each network.
2, start-up course interdepends, difficulty in starting: during power supply electrifying, the output of source of stable pressure is not achieved one in piece
Tentering value, band-gap reference can not start;Even if source of stable pressure can power with the help of start-up circuit in piece for band-gap reference, band
There is also degeneracy operating points for gap benchmark itself, it may occur however that the phenomenon that can not starting.
If 3, start-up course design is unreasonable, starting concussion problem easily occurs: as noted previously, as difficulty in starting problem,
System must be equipped with start-up circuit.But if the problems such as starting presence is out of order, starting current selection is unreasonable, system is easily sent out
Life is the problem of critical starting by two cycle of states with shaking.
Since source of stable pressure and bandgap reference voltage are the basal core modules of chip in piece, the above problem is directly threatened
To the normal work of entire chip, once will be unable to carry out follow-up test verifying work, crushing blow is caused to chip.
Summary of the invention
For the above problem existing for traditional nested type topological structure, the present invention provides a kind of current feedback zero-temperature coefficients
Regulated power supply in coefficient piece.The present invention utilizes current feedback mechanism, and feedback control network needed for generating band gap voltage shares
In the feedback control network of regulated power supply, two feedback control loop merging are reduced to one, to eliminate feedback control loop phase
Mutually nested problem.Relative to traditional nested type topological structure, current feedback topological structure of the invention, which has, easily to be compensated, is steady
The advantages of qualitative good, Yi Qidong.In addition, band gap voltage output is source of stable pressure output in this structure, to keep source of stable pressure defeated
Zero-temperature coefficient characteristic has been provided, and band gap voltage output is made to have both high PSRR and load driving capability.
The purpose of the present invention is what is be achieved through the following technical solutions:
Regulated power supply in a kind of current feedback zero-temperature coefficient piece, including current amplifier, power tube, feedback current pick up
Sense circuit, reference current generative circuit, in which:
The negative input end of the current amplifier is connected with the output end of reference current generative circuit, positive input terminal and feedback
The output of current pickup circuit is connected, and output end is connected with the grid of power tube, and feeder ear is connected with external high pressure power vd DH;
The drain electrode of the power tube is connected with external high pressure power vd DH, and source electrode is connected with low-tension supply VDDL in piece, piece
Interior low-tension supply VDDL is the output of regulated power supply in piece;
The input terminal of the feedback current pick-up circuit is connected with low-tension supply VDDL in piece.
Compared with the prior art, the present invention has the advantage that
1, in current feedback zero-temperature coefficient piece proposed by the invention regulated power supply realize in piece regulated power supply with
The fusion of bandgap reference voltage.The output of regulated power supply not only has electric current load capacity in current feedback zero-temperature coefficient piece
And itself it is also bandgap voltage reference with pressure stabilizing adjustment capability, there is zero-temperature coefficient characteristic.
2, regulated power supply topological structure stability substantially changes in current feedback zero-temperature coefficient piece proposed by the invention
It is kind.On the one hand two mutually nested feedback control loops in conventional topologies structure are reduced to one by monocycle current feedback topological structure
It is a, greatly improve the stability of system;On the other hand due to current feedback Low ESR feature, unique feedback control loop again only
There are a high resistant nodes, are more easier compensation circuit design.
3, the starting of regulated power supply topological structure is easy in current feedback zero-temperature coefficient piece proposed by the invention, is only deposited
A degeneracy operating point, the problem of interdepending there is no two loop start processes, start-up circuit design is easy, no starting
Concussion problem.
Specific embodiment
Further description of the technical solution of the present invention with reference to the accompanying drawing, and however, it is not limited to this, all to this
Inventive technique scheme is modified or replaced equivalently, and without departing from the spirit and scope of the technical solution of the present invention, should all be covered
Within the protection scope of the present invention.
As shown in Fig. 2, regulated power supply is by current amplifier 100, power tube in current feedback matrix provided by the invention
200, feedback current pick-up circuit 300, reference current generative circuit 400 form, in which:
The negative input end of the current amplifier 100 is connected with the output end of reference current generative circuit 400, positive input terminal
It is connected with the output of feedback current pick-up circuit 300, output end is connected with the grid of power tube 200, feeder ear and external high pressure
Power vd DH is connected;
The grid of the power tube 200 is connected with the output end of current amplifier 100, drain electrode and external high pressure power vd DH
It is connected, source electrode is connected with low-tension supply VDDL in piece, and low-tension supply VDDL is the output of regulated power supply in piece in piece;
The input terminal of the feedback current pick-up circuit 300 is connected with low-tension supply VDDL in piece, output end and the electricity
The positive input terminal of stream amplifier 100 is connected;
The reference current generative circuit 400 is for generating the reference current Iref unrelated with power supply, the output of the module
End is connected with the negative input end of the current amplifier 100.
In the present invention, as shown in figure 3, the current amplifier 100 is inputted by the first current input stage 101, the second electric current
Grade 102 is formed with current mirror 103, and the first current input stage 101 is identical with 102 structure of the second current input stage, is acted on and is
Reduce input impedance, improve output impedance with buffering input current.First input stage 101 is by the first transistor M1, third crystal
Pipe M3, the first bias current sources Ib1Composition, in which: the grid of the first transistor M1 is connected with the drain electrode of third transistor M3, into
One step and the first bias current sources Ib1It is connected;The source electrode of the first transistor M1 is connected with the grid of third transistor M3, as electricity
The positive input terminal of stream amplifier 100;The drain electrode of the first transistor M1 is extremely connected with the input of current mirror 103;Third transistor M3
Source electrode be connected with zero potential.The first transistor M1 is common gate input pattern, has low input impedance, the spy of high output impedance
Point;On this basis, third transistor M3 and the first bias current sources Ib1Local grid negative-feedback is constituted again, is further reduced
The input impedance of M1 improves the output impedance of M1.Therefore the input structure has good electric current input-output characteristic, can be with
Good absorption input current, and by its complete output without being influenced by late-class circuit.Similar, the second input stage 102 is by
Two-transistor M2, the 4th transistor M4, the second bias current sources Ib2Composition, in which: the grid of second transistor M2 and the 4th crystalline substance
The drain electrode of body pipe M4 is connected, further with the second bias current sources Ib2It is connected;The source electrode of second transistor M2 and the 4th transistor
The grid of M4 is connected, the negative input end as current amplifier 100;The drain electrode of second transistor M2 and the output of current mirror 103
Grade is connected, the output end as current amplifier 100;The source electrode of 4th transistor M4 is connected with zero potential.The current mirror 103
Be made of the 5th transistor M5, the 6th transistor M6, the 7th transistor M7, the 8th transistor M8, in which: the 5th transistor M5 and
The source electrode of 6th transistor M6 is connected with the outer high voltage power supply VDDH of piece;The drain electrode of 5th transistor M5 and the grid of the 6th transistor M6
Extremely it is connected, is further connected with the source electrode of the 7th transistor M7;The grid of 7th transistor M7 and the grid of the 8th transistor M8
It is connected, the input terminal as current mirror 103;The source electrode of 8th transistor is connected with the 6th transistor M6 drain electrode;8th transistor
Output end of the drain electrode as current mirror 103.The current mirror 103 is used to input current copying to its output end, and provides
Sufficiently high output impedance.In conclusion the input stage of current amplifier 100 has extremely low input impedance, it is conducive to absorb electricity
Stream, the electric current being absorbed into further pass through 103 mirror image of current mirror, are further aggregated into the output end of current amplifier 100 and turn
Voltage output signal is turned to, which has high resistant characteristic, therefore current amplifier 100 has enough transimpedance gains.
In the present invention, the current amplifier 100 is the main gain module in feedback control loop.Its effect mainly has
Following three points: 1) negative-feedback is introduced, control two-way input current is equal, and then by reference to electric current IrefControl feedback current picks up
Electric current in sense circuit 300, so in control sheet source of stable pressure output voltage size;2) sense when the load, can be passed through
Know, fault in enlargement signal adjusts rapidly, controls the output electric current of the power tube 200, to adapt to the variation of load current, stablize
Output voltage;3) influence exported using the fluctuation of negative feedback inhibition external power supply to source of stable pressure in piece, improves power supply rejection ratio.
In the present invention, the power tube 200 is high-voltage DMOS pipe, low in piece for external high pressure power vd DH to be isolated
Voltage source VDDL, and current output capability is provided for source of stable pressure in piece.
In the present invention, as shown in figure 4, the feedback current pick-up circuit 300 is by the first triode Q1, the second triode
Q2, first resistor R1 are constituted.The first triode Q1 and the second triode Q2 constitutes current-mirror structure: the first triode Q1's
Emitter is connected with the emitter of the second triode Q2, and is connected with zero potential;The base stage and the two or three of first triode Q1
The base stage of pole pipe Q2 is connected, and is connected with the collector of the first triode Q1;The collector of second triode Q2 is as feedback electricity
The output end of pick-up circuit 300 is flowed, output electric current is denoted as Iout.Due to the size of the first transistor Q1 and second transistor Q2
It is identical, base-emitter voltage VBEAlso identical, therefore export electric current IoutWith input current IinIt is equal in magnitude.The feedback current
The output voltage V of regulated power supply in the input terminal and piece of pick-up circuit 300outIt is connected, the current collection of further first triode Q1
Pole is connected by first resistor R1 with the input terminal of feedback current pick-up circuit 300.Therefore, the feedback current pick-up circuit
300 output electric current IoutWith the output voltage V of regulated power supply in pieceoutWith regard to meeting following relationship:
Vout=VBE1+VR1=ln (Iin/IS1)VT+R1Iin (1)。
As previously mentioned, Iin=Iout, therefore VoutIt can also indicate are as follows:
Vout=ln (Iout/IS1)VT+R1Iout (2)。
Wherein: IS1For the reverse saturation current of the first triode, VTFor thermodynamic voltage, R1For the resistance value of first resistor,
These three parameters are constant in the case where size determines, so the output electric current I of feedback current pick-up circuit 300outWith piece
Interior regulated power supply VoutOutput have one-to-one relationship, export electric current IoutIt reflects regulated power supply in piece and exports Vout's
Size.As previously mentioned, can control I by the negative feedback control of current amplifier 100outWith reference current IrefIt is equal, therefore
VoutSize can pass through IrefSize accurately set.
In addition, output voltage VoutTemperature coefficient depend on transistor base emitter voltage VBETemperature coefficient and
Pressure drop V on one resistance R1R1The sum of temperature coefficient.Due to the V of triodeBEWith negative temperature coefficient, temperature coefficient are as follows:
Therefore pass through control IoutTemperature coefficient, and then adjust resistance on pressure drop temperature coefficient so that the temperature coefficient
With triode VBENegative temperature coefficient offset, and then can control the output V of regulated power supply in pieceoutTemperature coefficient be zero.
Due to Iout=Iref, IoutThe adjusting of temperature coefficient can be by adjusting IrefTemperature coefficient realize that this work is by subsequent ginseng indirectly
Examine the completion of current source 400.The acquisition of this zero-temperature coefficient voltage depends on the band gap voltage of triode, therefore regulated power supply can also
To be considered as the band-gap reference of the zero-temperature coefficient with load driving capability.
In the present invention, the effect of the feedback current pick-up circuit 300 mainly has following three points: 1) by regulated power supply in piece
Output voltage be converted into feedback current proportional thereto and input to current amplifier;2) in the feedback control of current amplifier
The output voltage of regulated power supply in lower determining piece;3) as the core of band gap reference, the temperature coefficient of output voltage is adjusted.
In the present invention, as shown in figure 5, the reference current source 400 is by the 9th transistor M9, the tenth transistor M10, the tenth
One transistor M11, the tenth two-transistor M12, third transistor Q3, the 4th triode Q4, the 5th triode Q5, second resistance R2
Composition.The 9th transistor M9 is connected with the source electrode of the tenth transistor M10 with the outer high voltage power supply VDDH of piece;9th crystal
The grid of pipe M9 is connected with the grid of the tenth transistor M10, and then is connected with the drain electrode of the 9th transistor M9;11st transistor
The source electrode of M11 is connected with the drain electrode of the 9th transistor M9;The grid of 11st transistor M11 and the grid of the tenth two-transistor M12
Extremely it is connected, and then is connected with the drain electrode of the 11st transistor M11;The source electrode of tenth two-transistor M12 and the tenth transistor M10's
Drain electrode is connected;The drain electrode of tenth two-transistor M12 is connected with the collector of the 4th triode Q4.Transistor M9~M11 structure
At one group of current mirror, current mirror control keeps the electric current in third transistor Q3 equal with the electric current in the 4th transistor Q4.The
The base stage of three triode Q3 is connected with the base stage of the base stage of the 4th triode Q4 and the 5th triode Q5, and further connects
To the collector of the 4th triode Q4;The emitter of third transistor Q3, the 5th triode Q5 emitter with zero potential phase
Even;The emitter of 4th triode Q4 is connected by second resistance R2 with zero potential.The size and third of 5th triode Q5 is brilliant
The size of body pipe Q3 is identical;N times of the size of the size and third transistor Q3 of 4th triode Q4.The collection of 5th triode Q5
Electrode is the output end of reference current source 400, among electric current be reference current Iref.As previously mentioned, in current mirror
It is equal with electric current in Q4 to control lower Q3, and due to the size and V of Q5 and Q3BEElectric current all the same, therefore being flowed through in Q5, Q3, Q4
It is all the same.
Therefore, IrefIt can be determined by following formula:
Wherein: I3For the electric current flowed through in third transistor Q3, I4For the electric current flowed through in the 4th triode Q4, VBE3It is
The base collector voltage of three triode Q3, VBE4For the base collector voltage of the 4th triode Q4, R2For the resistance of second resistance
Value, IS3For the reverse saturation current of third transistor Q3, IS4For the reverse saturation current of the 4th triode Q4.
Since the size ratio of third transistor Q3 and the 4th triode Q4 is 1:N, there is IS3:IS4=1:N, and by
In I3=I4, therefore (4) formula can be further rewritten as:
Due to thermodynamic voltage VTWith absolute temperature is proportional, and proportionality coefficient is constant, therefore IrefWith positive temperature system
Number, and the size of its temperature coefficient can be set by the size ratio N of third transistor Q3 and the 4th triode Q4.
Further according to formula (1), the expression formula of source of stable pressure output voltage in piece are as follows:
As previously mentioned, VBE1With negative temperature coefficient, and thermodynamic voltage VTWith positive temperature coefficient, as first resistor R1
When with second resistance R2 for quasi-resistance, the temperature coefficient of the two is offseted.Therefore pass through appropriate adjustment proportionality coefficient N and the
The ratio between one resistance and second resistance R1/R2 can accomplish the voltage cancellation of two kinds of temperatures coefficient, realize the voltage of zero-temperature coefficient
Output.
In addition, in proposed by the invention structure only one feedback control loop, i.e., by Current amplifier different from traditional structure
The feedback loop that device 100, power tube 200,300 three of feedback current pick-up circuit are constituted.This feedback control loop on the one hand can
To complete to adjust power tube output electric current according to loading condition to maintain output voltage stabilization;On the other hand band gap can be provided
Voltage generates required feedback control.Because of only one feedback control loop, so there are two nesteds to feed back for the basic original that solves
Stability problem caused by influencing each other, and need to only guarantee a feedback loop stable, also greatly simplify the shape of compensation
Formula saves bring area overhead due to compensating electric capacity.Further, amplifier uses electric current to input shape in the feedback control loop
Formula, this form have the advantages that small signal impedance is low compared with original voltage input structure.Therefore amplifier input introduces
Secondary dominant pole, be located at higher frequency, the stability influence of whole loop is substantially reduced, the compensation of loop is easier to set
Meter.
For start-up course, in structure proposed by the invention only have reference current source 400 inside there are a letters
And operating point, i.e., in addition to normal working point, locked stable state that all transistors are turned off.And feedback control loop is negative due to only one
Feedback control logic, there is no such degeneracy operating points.Therefore, one need to be only designed for reference current source 400 simply
Start-up circuit.Due to not having the problem of feedback control loop nesting, system is also not present without the concern for boot sequence in start-up circuit
The problem of critical starting by two cycle of states with shaking.