CN101311869A - Electric current output circuit possessing voltage bias control and its method - Google Patents
Electric current output circuit possessing voltage bias control and its method Download PDFInfo
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- CN101311869A CN101311869A CNA2007101040951A CN200710104095A CN101311869A CN 101311869 A CN101311869 A CN 101311869A CN A2007101040951 A CNA2007101040951 A CN A2007101040951A CN 200710104095 A CN200710104095 A CN 200710104095A CN 101311869 A CN101311869 A CN 101311869A
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Abstract
The present invention relates to a current output circuit with bias control and a method thereof. The current output circuit comprises a current mirror circuit, a feedback control circuit and a reference current source. The current mirror circuit comprises a first transistor and a second transistor. The control of the feedback control circuit is used for ensuring that the value of the current flowing through the first transistor is corresponding to the value of the current flowing through the second transistor.
Description
Technical field
The invention relates to current output circuit, particularly the current output circuit of controlling about the tool bias voltage.
Background technology
Fig. 1 one is applied to the digital analog converter commonly used on the network.In this, digital analog converter 10 comprise a plurality of D/A conversion units (11,12 ... and 1n).Each D/A conversion unit is coupled by a pair of switches (by a transistor to realizing) and a current source (being realized by a transistor) and forms, wherein, the right grid of the transistor of each D/A conversion unit receives a digital signal and export a simulating signal V between pad PAD1 and PAD2
Out
Along with the evolution of manufacture of semiconductor, the supply voltage that is adopted reduces gradually, and (for example be: the 10M transmission mode in the Ethernet), more and more difficulty reaches to the requirement of peak value 5V when signal amplitude must reach the peak.See also Fig. 2, it is the circuit diagram of current mode digital analog converter (Current SteeringDAC) commonly used.Digital analog converter 20 comprise a plurality of D/ A conversion units 11,12 ... and 1n (only showing a D/A conversion unit 11 among the figure) and an impedance 13; Impedance 13 comprises one first matched impedance Z1 and one second matched impedance Z2.
If when applying the circuit of above-mentioned digital analog converter 20 with 0.18 micron system, its power supply potential V then
DDBe 1.8V.Please consult Fig. 2 again, the first simulating signal V
OutMonolateral amplitude peak size be 1.25V, when voltage reaches peak value between the first pad PAD1 and the second pad PAD2, the voltage headroom of the only remaining 550mV of the both end voltage of D/A conversion unit 11; Therefore, have influence on the operating voltage of the current source 113 (realizing) of D/A conversion unit 11 most probably, make the working point of this transistor 113 enter three polar regions, cause the electric current of D/A conversion unit 11 to diminish and amplitude descends by a transistor 113; As power supply potential V
DDWhen lower, this phenomenon will be more serious.
Traditional solution is for increasing the area of transistor 113, to reduce the saturated drain-source voltage (V of transistor 113
DS, SAT), make it be difficult for entering three polar regions; But this but can increase circuit area, and then makes cost promote, and causes competitive power to descend.
Summary of the invention
One of purpose of the present invention provides a kind of current output circuit and method thereof of tool bias voltage control, and this current output circuit can stable and running without distortion under low power supply.
One embodiment of the invention are: propose a kind of current output circuit, comprise: a reference current source is used to provide a reference current; One current mirroring circuit, it includes one first and one transistor seconds, and the drain electrode of this first transistor receives this reference current, and an output current is exported in the drain electrode of this transistor seconds, and wherein, this output current is corresponding to this reference current; And a feedback control circuit, be coupled between this reference current source and this current mirroring circuit, and according to the drain voltage of this first transistor and this transistor seconds with adjust this first and the grid bias of this transistor seconds.
Another embodiment of the present invention is: propose a kind of current output method, comprise: produce a reference current; Utilize a current mirroring circuit to export an output current, wherein, this output current is corresponding to this reference current, and this current mirroring circuit comprises a first transistor and a transistor seconds; Relatively the drain voltage of this first transistor and this transistor seconds is to export a comparative result; And according to this comparative result adjust this first with the grid bias of this transistor seconds.
Description of drawings
A D/A conversion unit synoptic diagram more than Fig. 1 is comprised by digital analog converter commonly used;
Fig. 2 is the circuit diagram of current mode digital analog converter commonly used;
Fig. 3 is the synoptic diagram of current output circuit proposed by the invention;
Fig. 4 is the synoptic diagram of the bias voltage output circuit that is applied to a digital analog converter proposed by the invention; And
Fig. 5 is the synoptic diagram that is applied to digital analog converter proposed by the invention.
[main element symbol description]
| 10、20、40、50 | Digital |
|
| 11、12、1n、43 | D/ |
|
| 13 | Impedance matching circuit | |
| 111、121、1n1、333、433 | Switch is right | |
| 113、123、1n3、420、413 | Current |
|
| 1111、1211、1n11、 | Transistor | |
| 1113、1213、1n13、 | Transistor | |
| 4331、4333 | Transistor | |
| 30 | Application circuit |
| 31 | Current output circuit |
| 33 | First circuit |
| 310 | |
| 320 | |
| 3201 | |
| 3203 | The |
| 330 | Reference current source |
| 333 | |
| 41 | The bias voltage output circuit |
| PAD1、PAD2 | Pad |
| Z1、Z2 | Matched impedance |
| I Q1、I Q2 | Reference current, second electric current |
| GND | Earth potential |
| V DD | Power supply potential |
| V CT | CONTROLLED POTENTIAL |
| V b2 | Bias |
| V out、V o | Analog output signal |
| V 1、V 2、V 3 | First current potential, second current potential, the 3rd current potential |
| D 1+、D 1-、D 2+、D 2- | Digital input signals |
Embodiment
Mentioned " coupling " speech comprises any indirect means that are electrically connected that directly reach at this in the middle of instructions and claims in the whole text.
The present invention is an example with the current output circuit of digital analog converter, and current output circuit only of the present invention also can be applicable on other circuit that need reference current.
See also Fig. 3, it is a current output circuit synoptic diagram of the present invention.Circuit 30 comprises a current output circuit 31 and one first circuit 33, and wherein an internal circuit 333 receptions of first circuit 33 are from second electric current I of this current output circuit 31
Q2
Current output circuit 31 comprises a current mirroring circuit 310, a feedback control circuit 320 and a reference current source 330.Reference current source 330 is in order to a reference current I to be provided
Q1Current mirroring circuit 310 includes a first transistor, transistor seconds 310A, 310B; Wherein the A1 of the first transistor 310A end is coupled to feedback control circuit 320, and has one second current potential V
2, its A2 end is coupled to a ground potential GND, and its control end A3 receives a CONTROLLED POTENTIAL V
CT, the electric current of the feasible the first transistor 310A that flows through is this reference current I
Q1Because this first transistor 310A and transistor seconds 310B are a current mirror framework, the electric current of the transistor seconds 310B that flows through is one second electric current I
Q2, and this second electric current I
Q2With first electric current I
Q1Proportional relation, in other words, its ratio of width to height (aspect ratio) with this first transistor 310A and transistor seconds 310B is relevant.Feedback control circuit 320 includes a comparator circuit 3201 and one the 3rd transistor 3203, and is coupled between current mirroring circuit 310 and the reference current source 330.Comparator circuit 3201 includes one first end D1, one second end D2 and an output terminal; Wherein, the first end D1 is coupled to the one first current potential V that has of transistor seconds 310B
1Drain electrode B1, the second end D2 is coupled to the first transistor 310A and has one second current potential V
2Drain electrode A1, and output terminal is in order to produce one the 3rd current potential V
3The 3rd transistor 3203 includes one the 3rd end D3 and one the 4th end D4, and its 3rd end D3 is coupled to the A1 end of the first transistor 310A, and the 4th end D4 is coupled to reference current source 330.The grid G 1 of the 3rd transistor 3203 receives the 3rd current potential V
3, so that this first current potential V
1With this second current potential V
2Can be identical in fact.In addition, first circuit 33 can be the circuit that needs reference current arbitrarily; Certainly, first circuit 33 can comprise that this transistor seconds 310B uses this second electric current I of reception
Q2, or first circuit 33 can comprise one the 3rd transistor in addition, the 3rd transistorized grid receives this CONTROLLED POTENTIAL V
CTForm another current mirroring circuit with the first transistor 310A.
See also Fig. 4, it is the bias voltage output circuit synoptic diagram that is applied to a digital analog converter proposed by the invention.Digital analog converter 40 comprises a bias voltage output circuit 41 of the present invention and a D/A conversion unit 43.In this embodiment, D/A conversion unit 43 comprises a pair of switches 433 and a current source 420 (it is realized with a transistor 310B); Bias voltage output circuit 41 comprises a first transistor 310A, a feedback control circuit 320 and a reference current source 330.Wherein, a transistor 310B of a transistor 310A of this bias voltage output circuit 41 and this D/A conversion unit 33 is a current mirror framework.In Fig. 3 and 4, still illustrated a transistor and be coupled between current source 330 and the 3rd transistor 3203, it can omit.
See also Fig. 5.Digital analog converter 50 comprises a bias voltage output circuit 41 and a plurality of D/A conversion units 43 of the present invention, and each D/A conversion unit 43 includes a current source 413 and pair of switches 433.Wherein, an embodiment of this current source 413 is a transistor 310B.Each current source 413 receives this control voltage V
CTAnd according to this control voltage V
CTWith output current.
In each D/A conversion unit 43 this receives corresponding digital signal to switch 433, promptly is respectively D
1+With D
1-(D
2+With D
2-..., D
N+With D
N-); And by this to convert digital signal to current signal; Each current signal totalling is formed an analog output signal (being output in PAD1 and PAD2 place).Wherein, still illustrated a plurality of transistors among Fig. 5 and be coupled between transistor 4331,4333 and PAD1, the PAD2, it can promote the performance of D/A conversion unit 43.And still there is a transistor to be coupled between current source 330 and the 3rd transistor 3203, for the transistor that is coupled between transistor 4331,4333 and PAD1, PAD2 increases.Those transistors all can omit.
See also Fig. 3,4 and 5, compare and produce one the 3rd current potential V at its output terminal by two ends (the first end D1 and the second end D2) to the comparator circuit 3201 of feedback control circuit 320
3This transistor 3203 receives the 3rd current potential V
3, so that the second current potential V
2Can be along with the first current potential V
1And becoming, that is the drain-source voltage (V of transistor seconds 420
DS) thereby be adjusted to drain-source voltage (V with the first transistor 310A
DS) identical, and then cause second electric current I
Q2In fact can be corresponding to reference current I
Q1
The above person only is one embodiment of the invention, and all those skilled in the art modify or variation in the equivalence that the spirit according to the present invention is done, and all should be covered by in the scope of protection of present invention.
Claims (12)
1. current output circuit comprises:
One reference current source is used to provide a reference current;
One current mirroring circuit includes one first and one transistor seconds, and the drain electrode of this first transistor receives this reference current, and an output current is exported in the drain electrode of this transistor seconds, and wherein, this output current is corresponding to this reference current; And
One feedback control circuit is coupled between this reference current source and this current mirroring circuit, and according to the drain voltage of this first transistor and this transistor seconds with adjust this first with the grid bias of this transistor seconds.
2. circuit as claimed in claim 1, wherein this transistor seconds is to be positioned at a digital analog converter.
3. circuit as claimed in claim 1, wherein this feedback control circuit comprises:
One comparator circuit compares the drain voltage of this first transistor and this transistor seconds; And
One the 3rd transistor is coupled to this reference current source and this first transistor, and its grid is coupled to an output terminal of this comparator circuit to adjust the drain voltage of this first transistor.
4. a bias voltage output circuit is used to provide a bias voltage signal to one first circuit, and this bias voltage output circuit comprises:
One reference current source is used to provide a reference current;
One the first transistor, the drain electrode of this first transistor receives this reference current, and the grid of this first transistor is accepted this bias voltage signal; And
One feedback control circuit, according to a builtin voltage of the drain voltage of this first transistor and this first circuit to adjust this bias voltage signal.
5. circuit as claimed in claim 4, wherein this first circuit comprises a transistor seconds, this builtin voltage is the drain voltage of this transistor seconds.
6. circuit as claimed in claim 4, wherein this first circuit comprises a transistor seconds, this transistor seconds couples mutually with this first transistor and forms a current mirroring circuit.
7. circuit as claimed in claim 4, wherein this first circuit is a digital analog converter.
8. circuit as claimed in claim 4, this first circuit wherein comprises:
One transistor seconds receives this this bias voltage signal to export one second electric current, and wherein this second electric current is corresponding with this reference current; And
One switch is right, couples this transistor seconds, in order to export an output terminal according to a digital signal to control this second electric current.
9. circuit as claimed in claim 4, wherein this feedback control circuit comprises:
One comparator circuit compares drain voltage and this builtin voltage of this first transistor; And
One the 3rd transistor is coupled between this reference current source and this first transistor, and its grid is coupled to an output terminal of this comparator circuit.
10. electric current output control method, it is used on the digital analog converter, and this digital analog converter comprises a current mirroring circuit, a feedback control circuit and a reference current source; Wherein, this current mirroring circuit comprises a first transistor, transistor seconds; This electric current output control method comprises:
Detect one first current potential of an end of this transistor seconds;
Detect one second current potential of an end of this first transistor;
Receive this first current potential of this transistor seconds and this second current potential of this first transistor by this feedback control circuit, and compare; And
Via the adjustment of this feedback control circuit, so that the current value that this first transistor flow through corresponds to the current value that this transistor seconds flows through.
11. a current output method comprises:
Produce a reference current;
Utilize a current mirroring circuit to export an output current, wherein, this output current is corresponding to this reference current, and this current mirroring circuit comprises a first transistor and a transistor seconds;
Relatively the drain voltage of this first transistor and this transistor seconds is to export a comparative result; And
According to this comparative result adjust this first with the grid bias of this transistor seconds.
12. method as claimed in claim 11, wherein this transistor seconds system is positioned at a digital analog converter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101040951A CN101311869A (en) | 2007-05-23 | 2007-05-23 | Electric current output circuit possessing voltage bias control and its method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101040951A CN101311869A (en) | 2007-05-23 | 2007-05-23 | Electric current output circuit possessing voltage bias control and its method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101311869A true CN101311869A (en) | 2008-11-26 |
Family
ID=40100538
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2007101040951A Pending CN101311869A (en) | 2007-05-23 | 2007-05-23 | Electric current output circuit possessing voltage bias control and its method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101311869A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101714007B (en) * | 2009-11-11 | 2011-11-16 | 钰创科技股份有限公司 | Current source having immunization effect on critical voltage variation and generation method thereof |
| CN109066290A (en) * | 2018-09-18 | 2018-12-21 | 杭州洪芯微电子科技有限公司 | Low-voltage space precision current mirror image circuit applied to laser driver |
| CN109765958A (en) * | 2019-03-29 | 2019-05-17 | 西安中颖电子有限公司 | A kind of constant current source driving circuit based on bicyclic negative-feedback |
| CN111542797A (en) * | 2017-12-18 | 2020-08-14 | 苹果公司 | Double-loop self-adaptive LDO (low dropout regulator) |
-
2007
- 2007-05-23 CN CNA2007101040951A patent/CN101311869A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101714007B (en) * | 2009-11-11 | 2011-11-16 | 钰创科技股份有限公司 | Current source having immunization effect on critical voltage variation and generation method thereof |
| CN111542797A (en) * | 2017-12-18 | 2020-08-14 | 苹果公司 | Double-loop self-adaptive LDO (low dropout regulator) |
| CN109066290A (en) * | 2018-09-18 | 2018-12-21 | 杭州洪芯微电子科技有限公司 | Low-voltage space precision current mirror image circuit applied to laser driver |
| CN109765958A (en) * | 2019-03-29 | 2019-05-17 | 西安中颖电子有限公司 | A kind of constant current source driving circuit based on bicyclic negative-feedback |
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Open date: 20081126 |