CN103716049B - Bias current generative circuit - Google Patents
Bias current generative circuit Download PDFInfo
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- CN103716049B CN103716049B CN201310746682.6A CN201310746682A CN103716049B CN 103716049 B CN103716049 B CN 103716049B CN 201310746682 A CN201310746682 A CN 201310746682A CN 103716049 B CN103716049 B CN 103716049B
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Abstract
The invention provides a kind of bias current generative circuit, including current steering DAC circuit and row buffering is entered to the electric current of the current steering DAC circuit output and the current buffering circuit of the bias current is exported, also include auxiliary circuit, the input of the auxiliary circuit is connected to two output ends of the current steering DAC circuit, and it is configured so that the voltage of described two outputs is roughly equal, the output end of the auxiliary circuit is connected to a voltage bias end of the current buffering circuit.The present invention dynamically changes the biasing of current buffer using auxiliary circuit, so that improve the output current of current steering DAC circuit sets up speed.
Description
Technical field
The present invention relates to electronic circuit, the current steering DAC circuit of more particularly to a kind of Single-end output.
Background technology
Current steering DAC circuit is commonly used to produce single-ended adjustable current as the biasing of other circuit modules.In some applications
In the laser tube drive circuit of occasion, such as optical communication circuit, current steering DAC circuit is not only needed to produce adjustable current as inclined
Put, in addition it is also necessary to which its adjustable current produced is used as modulated signal.This electric current for being accomplished by DAC generations can rapidly become with the time
Change.Due to the requirement of matching, the area for the pipe for producing electric current in DAC is larger, and the influence of its parasitic capacitance is more obvious, limitation
The quick foundation of DAC output signals.This phenomenon is particularly acute in the current steering DAC circuit that single tube current source is constituted.
The content of the invention
In order to solve the technical problem that the output current of current steering DAC circuit in the prior art can not quickly be set up, this hair
It is bright to provide a kind of bias current generative circuit, including current steering DAC circuit and the electric current to the current steering DAC circuit output
Enter row buffering and export the current buffering circuit of the bias current, in addition to auxiliary circuit, the input of the auxiliary circuit
Two output ends of the current steering DAC circuit are connected to, and are configured so that the voltage substantially phase of described two outputs
Deng the output end of the auxiliary circuit is connected to a voltage bias end of the current buffering circuit.
Further, the auxiliary circuit includes operational amplifier, two inputs of the operational amplifier respectively with
Two output ends of the current steering DAC circuit are connected.
Alternatively, the current buffering circuit includes the first triode and the second triode, the base of first triode
Pole is connected with the output end of the operational amplifier；The base stage of second triode is connected with predetermined bias voltage source.
Alternatively, the current buffering circuit include the first metal-oxide-semiconductor and the second metal-oxide-semiconductor, the grid of first metal-oxide-semiconductor with
The output end of the operational amplifier is connected；The grid of second metal-oxide-semiconductor is connected with predetermined bias voltage source.
Further, the current steering DAC circuit includes data input pin, negative phase current output and negative-phase sequence curent output
End, the negative phase current output is connected with the first input end of the operational amplifier, the negative-phase sequence curent output end and institute
The second input for stating operational amplifier is connected.
Preferably, the first input end of the operational amplifier is inverting input, and the second of the operational amplifier is defeated
It is normal phase input end to enter end.
The bias current generative circuit of the present invention, auxiliary circuit is connected by the output end in current steering DAC circuit so that
Bias current generative circuit can rapidly set up output current.
Brief description of the drawings
Fig. 1 is the schematic circuit of existing bias current generative circuit；
Fig. 2 is the voltage of A nodes and B node in Fig. 1 with the changing trend diagram of the input data of current steering DAC circuit；
Fig. 3 is the schematic circuit preferred embodiment of the bias current generative circuit of the present invention.
Embodiment
With reference to the accompanying drawings and detailed description the bias current generative circuit of the present invention is made further to retouch in detail
State, but it is not as a limitation of the invention.
Fig. 1 is the schematic circuit of biasing circuit generative circuit in the prior art, and the circuit includes current steering DAC circuit
Enter row buffering and the current buffering circuit of output bias current with the output current to current steering DAC circuit.Current steering DAC circuit
Input data DinCurrent source inside control DAC switches between two difference current output ends P, N.Current buffering circuit bag
Include the first triode Q1With the second triode Q2, Q1And Q2Base stage connection identical bias voltage source Vb.
First triode Q1Emitter stage be connected with the negative phase current output P of current steering DAC circuit, its colelctor electrode connection
By the circuit module of biasing/modulation.Second triode Q2Emitter stage and current steering DAC circuit negative-phase sequence curent output end N phases
Even, its colelctor electrode keeps floating.The electric current of the P ends output of current steering DAC circuit passes through Q1It is used for biasing what is biased after buffering
Circuit module, or as modulated signal to being modulated by the signal in modulation module.N-terminal output in order to P ends output
With simply pass through Q2Buffer, have no use.
In the embodiment, the triode in current buffering circuit can also be replaced with metal-oxide-semiconductor.
Due to the V of triodeBEWith ICExponential relationship（Then it is V if metal-oxide-semiconductorGSWith IDQuadratic relationship）, in Fig. 1
Node A, B voltage can be with DAC input data DinAnd change, the trend that it changes is as shown in Fig. 2 in DinIt is maximum and most
Hour node A and node B voltage difference reaches maximum.
Because a DAC internal current source parts are output to node A, another part is output to phase inside node B, therefore DAC
Induced current source output parasitic capacitance CpThe voltage at two ends is respectively VAAnd VB.Work as DinDuring change, current source is just had the two of DAC
Switch between individual output end, current source output parasitic capacitance CpCan first by current source charge or discharge, experience voltage jump it
DAC outputs afterwards could stablize, and reduce DAC outputs sets up speed.This phenomenon, in DinIt is the tightest when maximum or minimum
Weight.
Fig. 3 is the schematic circuit preferred embodiment of the bias current generative circuit of the present invention.The circuit is also
Include the auxiliary circuit of the output current for quickly setting up current steering DAC circuit, the auxiliary circuit includes operational amplifier, fortune
Two inputs for calculating amplifier are connected with two output ends of current steering DAC circuit respectively, and its output end is connected to electric current and delayed
Rush the Q of circuit1Base stage.
Add after the auxiliary circuit that output current is quickly set up, operational amplifier therein can cause two nodes of A, B
Voltage approximately equal so that in the absence of DAC output set up before need to CpThe process of charge and discharge, therefore DAC can be improved
Output signal sets up speed.
Above embodiment is only the illustrative embodiments of the present invention, it is impossible to be used in limit the present invention, the present invention
Protection domain be defined by the claims.Those skilled in the art can be in the essence and protection domain of the present invention, to this
Various modifications or equivalent substitution are made in invention, and these modifications or equivalent substitution also should be regarded as being within the scope of the present invention.
Claims (5)
1. a kind of bias current generative circuit, including current steering DAC circuit and the electric current to the current steering DAC circuit output enter
Row buffering and the current buffering circuit for exporting the bias current, it is characterised in that also including auxiliary circuit, the auxiliary circuit
Input be connected to two output ends of the current steering DAC circuit, and be configured so that the electricity of described two outputs
Pressure is roughly equal, and the output end of the auxiliary circuit is connected to a voltage bias end of the current buffering circuit,
Wherein, the auxiliary circuit includes operational amplifier, two inputs of the operational amplifier respectively with the electric current
Two output ends of rudder DAC-circuit are connected.
2. bias current generative circuit according to claim 1, it is characterised in that the current buffering circuit includes first
Triode and the second triode,
The base stage of first triode is connected with the output end of the operational amplifier；
The base stage of second triode is connected with predetermined bias voltage source.
3. bias current generative circuit according to claim 1, it is characterised in that the current buffering circuit includes first
Metal-oxide-semiconductor and the second metal-oxide-semiconductor,
The grid of first metal-oxide-semiconductor is connected with the output end of the operational amplifier；
The grid of second metal-oxide-semiconductor is connected with predetermined bias voltage source.
4. the bias current generative circuit according to Claims 2 or 3, it is characterised in that the current steering DAC circuit includes
Data input pin, negative phase current output and negative-phase sequence curent output end, the negative phase current output and the operational amplifier
First input end be connected, the negative-phase sequence curent output end is connected with the second input of the operational amplifier.
5. bias current generative circuit according to claim 4, it is characterised in that the first input of the operational amplifier
Hold as inverting input, the second input of the operational amplifier is normal phase input end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310746682.6A CN103716049B (en) | 2013-12-30 | 2013-12-30 | Bias current generative circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310746682.6A CN103716049B (en) | 2013-12-30 | 2013-12-30 | Bias current generative circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103716049A CN103716049A (en) | 2014-04-09 |
| CN103716049B true CN103716049B (en) | 2017-10-10 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310746682.6A Active CN103716049B (en) | 2013-12-30 | 2013-12-30 | Bias current generative circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103716049B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1482736A (en) * | 2002-04-22 | 2004-03-17 | 雷凌科技股份有限公司 | Gain amplifier circuit that minimizes the miller effect |
| CN202395750U (en) * | 2011-12-02 | 2012-08-22 | 上海贝岭股份有限公司 | Differential reference voltage buffer |
| CN103326681A (en) * | 2012-03-21 | 2013-09-25 | 三星电子株式会社 | Amplifier for output buffer, signal processing apparatus and amplifier circuit |
| CN103474015A (en) * | 2013-08-20 | 2013-12-25 | 北京大学深圳研究生院 | Output amplifier, digital-to-analogue converter, data drive circuit and display device |
| CN203661044U (en) * | 2013-12-30 | 2014-06-18 | 上海贝岭股份有限公司 | Bias current generating circuit |
-
2013
- 2013-12-30 CN CN201310746682.6A patent/CN103716049B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1482736A (en) * | 2002-04-22 | 2004-03-17 | 雷凌科技股份有限公司 | Gain amplifier circuit that minimizes the miller effect |
| CN202395750U (en) * | 2011-12-02 | 2012-08-22 | 上海贝岭股份有限公司 | Differential reference voltage buffer |
| CN103326681A (en) * | 2012-03-21 | 2013-09-25 | 三星电子株式会社 | Amplifier for output buffer, signal processing apparatus and amplifier circuit |
| CN103474015A (en) * | 2013-08-20 | 2013-12-25 | 北京大学深圳研究生院 | Output amplifier, digital-to-analogue converter, data drive circuit and display device |
| CN203661044U (en) * | 2013-12-30 | 2014-06-18 | 上海贝岭股份有限公司 | Bias current generating circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103716049A (en) | 2014-04-09 |
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