CN101557669B - High precision controllable current source - Google Patents
High precision controllable current source Download PDFInfo
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- CN101557669B CN101557669B CN200910126486A CN200910126486A CN101557669B CN 101557669 B CN101557669 B CN 101557669B CN 200910126486 A CN200910126486 A CN 200910126486A CN 200910126486 A CN200910126486 A CN 200910126486A CN 101557669 B CN101557669 B CN 101557669B
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Abstract
The invention discloses a high precision controllable current source which comprises a voltage-current switching circuit used for switching a reference voltage and generating a first current, a current mirror circuit used for switching the first current to a second current, and an output circuit used for switching the second current to a third current, outputting the third current and keeping the output current to be constant. The high precision controllable current source has simple structure, is easy to realize and can be applied to an LED driving circuit.
Description
Technical field
The invention belongs to field of analog integrated circuit, relate in particular to a kind of high precision controllable current source.
Background technology
LED display rose from the late nineteen eighties, and in the short more than ten years, LED display has caused social extensive concern as a high-tech product.Adopt system controlled by computer, the LED display that light, electricity are combined together has become the means that important present information is issued, is widely used in fields such as securities trading, finance, traffic, physical culture, advertisements.LED display mainly is spliced by the display unit that light-emitting diode (LED) and drive circuit thereof are formed, so the Drive and Control Circuit that the display effect of LED display (like brightness, color etc.) adopts with it is closely related.
Be to obtain good display, LED adopts constant-current driving, and can obtaining well and stably electric current through drive circuit, that LED is shown is more even, and prolongs its life-span; The size of drive current has also determined brightness and the color of LED simultaneously.Like this, the design of high-precision controllable current source will be that whole LED drives the important ring in the design.
Summary of the invention
The technical problem that the present invention will solve provides a kind of high precision controllable current source.
High precision controllable current source provided by the invention comprises:
Voltage-current converter circuit is used for reference voltage is changed, and generates first electric current;
Current mirroring circuit, being used for said first current conversion is second electric current;
Output circuit, being used for said second current conversion is the output of the 3rd electric current, and makes output current constant.
Preferably, said voltage-current converter circuit comprises first nmos pass transistor, first operational amplifier and first resistance, wherein:
The source electrode of said first nmos pass transistor is through said first grounding through resistance, and drain electrode connects the input of said current mirroring circuit, and grid connects the output of said first operational amplifier;
The positive input of said first operational amplifier connects reference voltage, and reverse input end is connected between the source electrode and said first resistance of said first nmos pass transistor.
Preferably, said current mirroring circuit comprises a PMOS transistor, the 2nd PMOS transistor, the 3rd PMOS transistor and second operational amplifier, wherein:
The transistorized source electrode of a said PMOS connects power supply, and drain electrode connects the output of said voltage-current converter circuit, grid and drain electrode short circuit, and grid also connects the positive input of transistorized grid of said the 2nd PMOS and said second operational amplifier;
The transistorized source electrode of said the 2nd PMOS connects power supply, and drain electrode connects the reverse input end of transistorized source electrode of said the 3rd PMOS and said second operational amplifier;
The transistorized grid of said the 3rd PMOS connects the output of said second operational amplifier, and drain electrode connects the input of said output circuit.
Preferably, said output circuit comprises the 3rd operational amplifier, four-operational amplifier, the 5th operational amplifier, second nmos pass transistor, the 3rd nmos pass transistor, the 4th nmos pass transistor, second resistance and the 3rd resistance, wherein:
The positive input of said the 3rd operational amplifier connects reference voltage, reverse input end and output short circuit and said second resistance, the 3rd grounding through resistance through connecting;
The reverse input end of said four-operational amplifier connects the common port of said second resistance and the 3rd resistance, and positive input connects the drain electrode of said second nmos pass transistor;
The source ground of said second nmos pass transistor, drain electrode connects the output of said voltage-current converter circuit and the positive input of said the 5th operational amplifier, and grid connects the output of said four-operational amplifier;
The source ground of said the 3rd nmos pass transistor, grid connects the output of said four-operational amplifier, and drain electrode connects the reverse input end of said the 5th operational amplifier and the source electrode of said the 4th nmos pass transistor;
The grid of said the 4th nmos pass transistor connects the input of said the 5th operational amplifier, drains to be the output of said high precision controllable current source.
High precision controllable current source of the present invention is simple in structure, is easy to realize, can be applied in the led drive circuit.
Description of drawings
Fig. 1 is the structure chart of the high precision controllable current source of the embodiment of the invention.
Embodiment
For making the object of the invention, technical scheme and advantage express clearlyer, the present invention is remake further detailed explanation below in conjunction with accompanying drawing and specific embodiment.
At first, technical term involved in the present invention is described:
PMOS:P-channel metal oxide semiconductor FET, the P-channel metal-oxide-semiconductor field-effect transistor;
NMOS:N-channel metal oxide semiconductor FET, n channel metal oxide semiconductor field effect transistor.
With reference to Fig. 1, the high precision controllable current source of the embodiment of the invention comprises voltage-current converter circuit 10, current mirroring circuit 20 and output circuit 30, wherein:
Voltage-current converter circuit 10 is used for reference voltage is changed, and generates first electric current I
1
Below the detailed structure and the operation principle of voltage-current converter circuit 10, current mirroring circuit 20 and output circuit 30 are described.
Said voltage-current converter circuit 10 comprises the first nmos pass transistor N1, the first operational amplifier OP1 and first resistance R 1; Said current mirroring circuit 20 comprises a PMOS transistor P1, the 2nd PMOS transistor P2, the 3rd PMOS transistor P3 and the second operational amplifier OP2; Said output circuit 30 comprises the 3rd operational amplifier OP3, four-operational amplifier OP4, the 5th operational amplifier OP5, the second nmos pass transistor N2, the 3rd nmos pass transistor N3, the 4th nmos pass transistor N4, second resistance R 2 and the 3rd resistance R 3.
The grid of the said first nmos pass transistor N1 is connected with the output of the said first operational amplifier OP1; The source electrode of the first nmos pass transistor N1 connects reverse input end and said first resistance R 1 high-end of the first operational amplifier OP1, and the drain electrode of the first nmos pass transistor N1 is connected with the drain electrode of a PMOS transistor P1; The positive input of the said first operational amplifier OP1 meets reference voltage REF, and the low side of first resistance R 1 is connected with ground wire; The grid of a said PMOS transistor P1, drain electrode short circuit also connect drain electrode and the grid of the 2nd PMOS transistor P1 and the positive input of the second operational amplifier OP2 of the first nmos pass transistor N1, and the source electrode of a PMOS transistor P1 and the 2nd PMOS transistor P2 meets power vd D;
The drain electrode of the 2nd PMOS transistor P2 is connected with the source electrode of the 3rd PMOS transistor P3, also connects the reverse input end of the second operational amplifier OP2 simultaneously, and the output of the said second operational amplifier OP2 is connected with the grid of the 3rd PMOS transistor P3; The drain electrode of said the 3rd PMOS transistor P3 is connected with the drain electrode of the second nmos pass transistor N2;
Said the 3rd operational amplifier OP3 positive input connects reference voltage REF; Its reverse input end is with the output short circuit and connect the high-end of second resistance R 2; The low side of said second resistance R 2 is connected with the 3rd the high-end of resistance R 3, and connects the reverse input end of four-operational amplifier OP4; The low side of said the 3rd resistance R 3 is connected with ground wire;
The positive input of said four-operational amplifier OP4 connects drain electrode and the drain electrode of the second nmos pass transistor N2 and the positive input of the 5th operational amplifier OP5 of the 3rd PMOS transistor P3, the output termination second nmos pass transistor N2 of four-operational amplifier OP4 and the grid of the 3rd nmos pass transistor N3; The grid of output termination the 4th nmos pass transistor N4 of the 5th operational amplifier OP5, the reverse input end of the 5th operational amplifier OP5 connect the drain electrode of source electrode and the 3rd nmos pass transistor N3 of the 4th nmos pass transistor N4; The source electrode of said second and third nmos pass transistor N2, N3 is connected with ground wire, and the drain electrode of the 4th nmos pass transistor N4 is the output of said high precision controllable current source, the electric current I that its output is constant
3
The first nmos pass transistor N1 and first resistance R 1 constitute feedback loop; Its output with the first operational amplifier OP1 feeds back to its reverse input end; The first operational amplifier OP1 is in the close loop negative feedback state; Can know according to short, the empty disconnected principle of void, the reverse input end of the first operational amplifier OP1, the source voltage terminal of the first nmos pass transistor N1 all equals reference voltage V
REFFlow through the electric current I of the first nmos pass transistor N1 like this
1Should for:
The one PMOS transistor P1, the 2nd PMOS transistor P2, the 3rd PMOS transistor P3 and the second operational amplifier OP2 have constituted novel current-mirror structure.The second operational amplifier OP2 and the 3rd PMOS transistor P3 are configured to clamp circuit; Make the source-drain voltage of a said PMOS crystal P1 and the 2nd PMOS transistor P2 equate; Thereby guarantee the high accuracy coupling of two branch currents of current mirroring circuit 20, and can draw the electric current I that flows through the 3rd PMOS transistor P3
2For:
Wherein, Lp1 is the channel length of a PMOS transistor P1, and Wp1 is the channel width of a PMOS transistor P1; Lp2 is the channel length of the 2nd PMOS transistor P2, and Wp2 is the channel width of the 2nd PMOS transistor P2.
The 3rd operational amplifier OP3, the 3rd resistance R 3 and the 4th resistance R 4 constitute bleeder circuits, make the voltage V of positive input of four-operational amplifier OP4
IN4For:
Four-operational amplifier OP4 is in the close loop negative feedback state, and the voltage of its positive input and reverse input end keeps equating.Therefore; The drain voltage of the second nmos pass transistor N2 also should equal the dividing potential drop of reference voltage between resistance R 2 and R3; The 5th operational amplifier OP5 is used for the drain electrode of clamp second nmos pass transistor N2 and the 3rd nmos pass transistor N3; The drain voltage of such the 3rd nmos pass transistor N3 also is clamped to the dividing potential drop of reference voltage between resistance R 2 and R3, makes the output voltage of said high precision controllable current source not receive the influence of load variations.The leakage of the 3rd nmos pass transistor N3, source voltage V
DSN3Be fixed to:
Because the 3rd nmos pass transistor N3 is identical with the drain voltage of the second nmos pass transistor N2, therefore the current ratio of the second nmos pass transistor N2 and the 3rd nmos pass transistor N3 depends on the breadth length ratio between them fully, can draw the output current I of controllable current source
3, its size is determined by following formula:
Wherein, W
N3Be the channel width of the 3rd nmos pass transistor N3, L
N3It is the channel length of the 3rd nmos pass transistor N3.
The output current that can be found out controllable current source by following formula is directly proportional with the inverse of the resistance value of first resistance R 1, can export different big or small electric currents in the Control current source through the resistance value of adjusting first resistance R 1, to satisfy the demand of LED to the different driving electric current.
The above is merely preferred embodiment of the present invention, and is in order to restriction the present invention, not all within spirit of the present invention and principle, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (4)
1. a high precision controllable current source is characterized in that, comprising:
Voltage-current converter circuit is used for reference voltage is changed, and generates first electric current;
Current mirroring circuit, being used for said first current conversion is second electric current;
Output circuit, being used for said second current conversion is the output of the 3rd electric current, and makes output current constant;
Said voltage-current converter circuit comprises first nmos pass transistor, first operational amplifier and first resistance, wherein:
The source electrode of said first nmos pass transistor is through said first grounding through resistance, and drain electrode connects the input of said current mirroring circuit, and grid connects the output of said first operational amplifier;
The positive input of said first operational amplifier connects reference voltage, and reverse input end is connected between the source electrode and said first resistance of said first nmos pass transistor;
Said current mirroring circuit comprises a PMOS transistor, the 2nd PMOS transistor, the 3rd PMOS transistor and second operational amplifier, wherein:
The transistorized source electrode of a said PMOS connects power supply, and drain electrode connects the output of said voltage-current converter circuit, grid and drain electrode short circuit, and grid also connects the positive input of transistorized grid of said the 2nd PMOS and said second operational amplifier;
The transistorized source electrode of said the 2nd PMOS connects power supply, and drain electrode connects the reverse input end of transistorized source electrode of said the 3rd PMOS and said second operational amplifier;
The transistorized grid of said the 3rd PMOS connects the output of said second operational amplifier, and drain electrode connects the input of said output circuit;
Said output circuit comprises the 3rd operational amplifier, four-operational amplifier, the 5th operational amplifier, second nmos pass transistor, the 3rd nmos pass transistor, the 4th nmos pass transistor, second resistance and the 3rd resistance, wherein:
The positive input of said the 3rd operational amplifier connects reference voltage, reverse input end and output short circuit and said second resistance, the 3rd grounding through resistance through connecting;
The reverse input end of said four-operational amplifier connects the common port of said second resistance and the 3rd resistance, and positive input connects the drain electrode of said second nmos pass transistor;
The source ground of said second nmos pass transistor, drain electrode connects the output of said current mirroring circuit and the positive input of said the 5th operational amplifier, and grid connects the output of said four-operational amplifier;
The source ground of said the 3rd nmos pass transistor, grid connects the output of said four-operational amplifier, and drain electrode connects the reverse input end of said the 5th operational amplifier and the source electrode of said the 4th nmos pass transistor;
The grid of said the 4th nmos pass transistor connects the output of said the 5th operational amplifier, drains to be the output of said high precision controllable current source.
2. high precision controllable current source as claimed in claim 1 is characterized in that:
The resistance value of said first resistance is adjustable, and different resistance values is corresponding to the different electric flow valuve of said first electric current.
3. high precision controllable current source as claimed in claim 1 is characterized in that:
Said second operational amplifier and the 3rd PMOS transistor are configured to clamp circuit, make a said PMOS transistor and the transistorized source-drain voltage of the 2nd PMOS equate, thereby make said first electric current and second electric current be complementary.
4. high precision controllable current source as claimed in claim 1 is characterized in that:
Said the 5th operational amplifier is configured for the drain electrode of said second nmos pass transistor of clamp and the drain electrode of said the 3rd nmos pass transistor, makes that the output current of said high accuracy controllable voltage source is constant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910126486A CN101557669B (en) | 2009-03-11 | 2009-03-11 | High precision controllable current source |
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| Application Number | Priority Date | Filing Date | Title |
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| CN200910126486A CN101557669B (en) | 2009-03-11 | 2009-03-11 | High precision controllable current source |
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| CN101557669A CN101557669A (en) | 2009-10-14 |
| CN101557669B true CN101557669B (en) | 2012-10-03 |
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| CN200910126486A Expired - Fee Related CN101557669B (en) | 2009-03-11 | 2009-03-11 | High precision controllable current source |
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| CN102455727B (en) * | 2010-10-28 | 2013-10-23 | 南京航空航天大学 | Current control circuit with rang of 100pA-1muA |
| CN102573190B (en) * | 2010-12-27 | 2015-02-11 | 深圳市长运通光电技术有限公司 | Control method and system for output current of LED (Light Emitting Diode) driving circuit |
| CN102098852B (en) * | 2011-02-01 | 2013-07-10 | 北京大学 | Small-area power tube-based low-mismatching multi-channel light-emitting diode (LED) constant current source driving circuit |
| CN102622958B (en) * | 2011-02-01 | 2014-09-24 | 北京大学 | Local matching-based multichannel LED constant current source driving circuit |
| CN102622957B (en) * | 2011-02-01 | 2014-07-02 | 北京大学 | Multichannel LED constant current source driving circuit based on MOSFET of linear region with constant grid voltage |
| CN102542979A (en) * | 2011-11-08 | 2012-07-04 | 南京微盟电子有限公司 | Constant current light emitting diode (LED) driving circuit |
| CN103246306A (en) * | 2013-04-11 | 2013-08-14 | 刘雄 | High-precision three-port chip |
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| CN103926971A (en) * | 2014-04-22 | 2014-07-16 | 西安电子科技大学 | Current reference circuit for light sensor |
| CN104184320B (en) * | 2014-08-27 | 2017-01-18 | 电子科技大学 | Output current controllable type current source |
| CN104796127A (en) * | 2015-04-10 | 2015-07-22 | 西安电子科技大学 | Infrared light emitting diode driving circuit for infrared approach sensors |
| CN105261327B (en) * | 2015-10-08 | 2018-12-25 | 俞德军 | Digital form adjustable constant-flow driving circuit |
| CN108227812A (en) * | 2016-12-14 | 2018-06-29 | 中国航空工业集团公司西安航空计算技术研究所 | A kind of high stability high precision current source circuit |
| CN108848594B (en) * | 2018-07-11 | 2024-08-06 | 上海艾为电子技术股份有限公司 | LED drive circuit and multi-path LED lighting system |
| CN111601429B (en) * | 2020-06-03 | 2022-08-26 | 西安中颖电子有限公司 | Constant current driving circuit |
| CN114415773B (en) * | 2022-01-20 | 2024-03-19 | 广州昂瑞微电子技术有限公司 | High-precision current source circuit |
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2009
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Patent Citations (5)
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|---|---|---|---|---|
| US5793248A (en) * | 1996-07-31 | 1998-08-11 | Exel Microelectronics, Inc. | Voltage controlled variable current reference |
| CN1702589A (en) * | 2005-06-21 | 2005-11-30 | 电子科技大学 | Current source with very high output impedance |
| EP1881391A1 (en) * | 2005-08-17 | 2008-01-23 | Rohm Co., Ltd. | Constant current circuit, and inverter and oscillation circuit using such constant current circuit |
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Non-Patent Citations (1)
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