CN106856405B - A kind of switching current device and the digital analog converter based on the device - Google Patents
A kind of switching current device and the digital analog converter based on the device Download PDFInfo
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Abstract
The invention discloses a kind of switching current device and based on the digital analog converter of the device.The device includes: complementary current switch module to be corrected and correcting circuit module；Correcting circuit module includes: comparator, Corrective control unit and differential switch gating control cells；Complementary current switch module to be corrected includes: subnumber mode converter, the first current source, the second current source, first switch unit and second switch unit；Comparator is connect with the output end of complementary current switch module to be corrected and Corrective control unit respectively, Corrective control unit is connect with subnumber mode converter and differential switch gating control cells respectively, and differential-strobe control unit is connect with first switch unit and second switch unit respectively；First switch unit is connected between the first current source and output end, and second switch unit is connected between the second current source and output end.The present invention fundamentally reduces the error of output electric current by the mismatch for inhibiting switch unit to introduce.
Description
Technical field
The present invention relates to d convertor circuit technical fields, and in particular to a kind of switching current device and is based on the device
Digital analog converter.
Background technique
Digital analog converter (DAC) is as the important bridge converted between numeric field and analog domain, in signal processing and communication
Important role in field.With the raising of information content in modern communications, the speed of logarithm mode converter has higher want
It asks.Simultaneously because the multiplexing of frequency spectrum, so that simultaneous signal spectrum range is wider in single channel, to reduce different frequency range
The interference of interior signal, while reducing the interference of the harmonic wave of non-linear introducing, it is desirable that digital analog converter has the higher linearity.DAC
The linearity generally use spurious-free dynamic range (SFDR) to describe, SFDR is defined as in the frequency range that output is concerned about, letter
The ratio between the energy of number energy and the maximum harmonic wave of energy.Reaching higher SFDR in broader frequency range is current application neck
One of the hot spot for developing the new performance requirement and ongoing research area that logarithm mode converter proposes in domain.
In high-speed A/D converter, current mode digital-to-analog converter because its than other structures DAC speed faster, power consumption
It is low, and carrying load ability is strong, thus be widely adopted.Fig. 1 is the basic structure of current mode digital-to-analog converter, referring to Fig.1, electric current
Type digital analog converter includes one group of current source permutation and a pair of switches unit being connected with each current source.Input number letter
The on-off of number control switch unit, thus the specific output end of the current direction for controlling each current source, the electricity from current source
Stream carries out addition summation in two output ends, and the difference of two output ends is the corresponding analog output of input digital signal.
In traditional current mode DAC, the principal element for influencing SFDR performance can probably be divided into following two major classes: static
Factor and dynamic factor.Wherein Static implicit method, which refers mainly to Current-source matching error, causes output end to turn in each input digital code
Change the existing error between ideal output when output is stablized.Resistance drop causes same cabling in circuit each on cabling simultaneously
The change of gradient of point voltage and the influence of temperature gradient bring can also introduce between current source reality output and ideal output
Error will introduce harmonic wave relevant to input signal in output end when input digital signal is related to these output errors
To reduce SFDR.In order to reduce Current-source matching error, simplest method is to use bigger transistor area to improve
Matching degree, but the increase of transistor area will lead to the increase of parasitic capacitance, to limit the speed of DAC.And it is simple
The area for increasing current source can not improve error brought by cabling pressure drop and temperature gradient, thus more effectively and more
The method of essence is to use alignment technique, directly will be within the output calibration of current source to required accuracy rating.
It is mainly related to the digital word handoff procedure of digital analog converter for influencing the dynamic factor of SFDR.In digital word
In handoff procedure, due to time order error, power and the mismatch of switching tube of driving signal etc. can be all introduced into handoff procedure
Non-ideal output, to introduce burr.To reduce the SFDR of output signal.In addition to this, finite output impedance is that limitation is whole
The key factor of a DAC SFDR in high frequency, relation schematic diagram of the Fig. 2 between current source output impedance and SFDR, referring to Fig. 2
It is found that the increase SFDR with output impedance is improved.Since output impedance is finite value, and due to the shadow of parasitic capacitance
It rings, leads in output impedance that there are capacitive ingredients, in high frequency, output impedance further deteriorates.
Fig. 3 is the structure and schematic diagram of complementary electrical flow pattern digital analog converter, and referring to Fig. 3, the prior art proposes a kind of mutual
Mend current mode digital-to-analog converter.Its key is the addition of a pair of of complementary switch and respective complementary electric current, in this configuration, right
For any one current source and switch unit, under the control of any switch control signal, two outputs of the unit
There is electric current output in end, but the difference exported keeps certain.When the electric current of two-way output meets certain proportionate relationship,
The effective more traditional structure of output impedance is greatly improved, to improve SFDR.
The correction of current source is to improve the effective means of the static accuracy of current mode digital-to-analog converter.Fig. 4 is band correction function
The structure and schematic diagram of the current mode digital-to-analog converter of energy, referring to Fig. 4, in correction course, the output and ginseng of adjustable current source
It examines current source to be compared, the size of current of the error controling signal control adjustable current source of comparator output, until adjustable electric
Stream source reaches certain accuracy rating, and corresponding switching regulated power supply is exported after correction.Increase compared to tradition
Current source area by improve it is matched in a manner of, correction can more guarantee the precision of current source, resist temperature gradient variation and
It is more efficient in terms of cabling pressure drop, while more saving area.
It needs to correct due in conventional correction, all only existing single channel current source, and in complementary electrical flow structure, it is last
Output electric current is the difference of two current sources, that is to say, that there is electric current in the two-way complementary output of switch control, and its
Difference is only theoretical output valve.And due to the mismatch of the switch unit for controlling output, cause in complementary structure
When two current source differences are theoretical difference, the difference current of reality output still deposits deviation.
Summary of the invention
For the defects in the prior art, the digital-to-analogue the present invention provides a kind of switching current device and based on the device turns
Parallel operation, which can effectively inhibit the mismatch of switch unit introducing, compared to tradition just for current source itself
Correction for drift technology, the present invention can fundamentally reduce error.
The invention proposes a kind of switching current devices, which is characterized in that including complementary current switch module to be corrected and
Correcting circuit module；
The correcting circuit module includes: comparator, Corrective control unit and differential switch gating control cells；
The complementary current switch module to be corrected includes: subnumber mode converter, the first current source, the second current source, and
One switch unit and second switch unit；
The output end of the complementary current switch module to be corrected is connect with the input terminal of the comparator, the comparator
Output end connect with the input terminal of the Corrective control unit, the output end of the Corrective control unit respectively with the subnumber
Mode converter is connected with the differential switch gating control cells, and the differential switch gating control cells are respectively with described first
Switch unit is connected with the second switch unit, and the Corrective control unit generates orientation output control letter according to comparison result
Number, and the orientation is exported into control signal and is sent to the differential switch gating control cells, the differential switch gating control
Unit processed exports control signal according to the orientation, and complementary electrical flow control signals are sent to the complementary current to be corrected and are switched
Module or spare complementary current switch module；
The subnumber mode converter is connect with first current source, and the first switch unit is connected to first electricity
Between stream source and the output end of the complementary current switch module to be corrected, the second switch unit is connected to second electricity
Between stream source and the output end of the complementary current switch module to be corrected；
The comparator, the electric current for receiving and the output end of the complementary current switch module to be corrected exports
Value, and comparison result is sent to the Corrective control unit；
The Corrective control unit controls signal for generating size of current according to the comparison result, and by the electricity
Stream size control signal is sent to the subnumber mode converter, so that the subnumber mode converter is controlled according to the size of current
Signal controls the output of first current source；
The differential switch gating control cells, for receiving complementary electrical flow control signals, and according to the complementary current
It controls signal and controls the first switch unit and the second switch unit.
Optionally, the correcting circuit module further include: spare complementary current switch module, current output terminal, third are opened
Close unit and the 4th switch unit；
The spare complementary current switch module is connect with the differential switch gating control cells, and the third switch is single
Member is connected between the current output terminal and the complementary current switch module to be corrected, and the 4th switch unit is connected to
Between the current output terminal and the spare complementary current switch module.
Optionally, the Corrective control unit is also used to:
Orientation output control signal is generated according to the comparison result, and the orientation is exported into control signal and is sent to difference
Switch-dividing gating control cells；
Correspondingly, the differential switch gating control cells are also used to:
Control signal is exported according to the orientation, the complementary electrical flow control signals are sent to complementary current to be corrected and are opened
Close module or spare complementary current switch module.
Optionally, the correcting circuit module further include: the 5th switch unit and reference current source；
5th switch unit is connected between the complementary current switch module to be corrected and the comparator；
The reference current source is connected between the 5th switch unit and the comparator.
Optionally, the reference current source includes: the 5th current source and the 6th current source；
5th current source is connected between the 5th switch unit and the positive input terminal of the comparator, and described
Six current sources are connected between the 5th switch unit and the negative input end of the comparator.
Optionally, the Corrective control unit is also used to:
The correcting circuit module further include: spare complementary current switch module, current output terminal, third switch unit and
4th switch unit；
The spare complementary current switch module is connect with the differential switch gating control cells, and the third switch is single
Member is connected between the current output terminal and the complementary current switch module to be corrected, and the 4th switch unit is connected to
Between the current output terminal and the spare complementary current switch module；
First switch control signal is generated according to comparison result and second switch controls signal；
The first switch controls signal, for being connected to the 4th switch unit and the described 5th in correcting state
Switch unit；In non-correcting state, the 4th switch unit and the 5th switch unit are disconnected；
The second switch controls signal, for disconnecting the third switch unit in correcting state；In non-correction shape
When state, it is connected to the third switch unit.
Optionally, the output end of the complementary current switch module to be corrected includes: the first output end and second output terminal；
The correcting circuit module further include: spare complementary current switch module, current output terminal, third switch unit and
4th switch unit；
The spare complementary current switch module is connect with the differential switch gating control cells, and the third switch is single
Member is connected between the current output terminal and the complementary current switch module to be corrected, and the 4th switch unit is connected to
Between the current output terminal and the spare complementary current switch module；
First output end is connect with the negative input end of the comparator, the second output terminal and the comparator
Positive input terminal connection；
Correspondingly, the first switch unit, the second switch unit, the third switch unit, the described 4th open
It closes unit and the 5th switch unit includes: first switch and the second switch；
The first switch is connect with the first output end, and the second switch is connect with the second output terminal.
Optionally, the differential switch gating control cells are also used to:
Difference control signal is generated according to the complementary electrical flow control signals；
The first switch and described of the first switch unit is controlled according to the positive phase signals of the difference control signal
The second switch of two switch units, and the of the first switch unit is controlled according to the inversion signal of the difference control signal
The first switch of two switches and the second switch unit.
The invention also provides a kind of digital analog converters characterized by comprising decoder interconnected and switch electricity
Flow array；
The switching current array includes at least one above-mentioned switching current device；
The decoder, for the digital input signals received to be converted to difference control signal, and by the difference
Control signal be sent to the switching current array so that the switching current array according to the difference control signal output with
The corresponding analog signal of digital input signals.
Optionally, the switching current array includes: sharing module group；
The sharing module group includes: multiple switch current module, switching switch and a correcting circuit module；
The switching switch is separately connected the multiple switching current module and the correcting circuit module；
The correcting circuit module, for being corrected respectively to each switching current module by switching switch.
As shown from the above technical solution, switching current device proposed by the present invention, after output switching element
It exports electric current and generates size of current control signal, and control the current output value of signal control current source according to size of current, with
Achieve the purpose that the mismatch for inhibiting switch unit to introduce, compared to tradition just for the correction for drift technology of current source itself, energy
It is enough fundamentally to reduce error.
Detailed description of the invention
The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, and attached drawing is schematically without that should manage
Solution is carries out any restrictions to the present invention, in the accompanying drawings:
Fig. 1 shows the basic structure of current mode digital-to-analog converter；
Fig. 2 shows the relation schematic diagrams between current source output impedance and SFDR；
Fig. 3 shows the structure and schematic diagram of complementary electrical flow pattern digital analog converter；
Fig. 4 shows the structure and schematic diagram of the current mode digital-to-analog converter with calibration function；
Fig. 5 shows the structural schematic diagram of the switching current device of one embodiment of the invention offer；
Fig. 6 shows the complementary current switch module to be corrected in the switching current device of one embodiment of the invention offer
Structural schematic diagram；
Fig. 7 show another embodiment of the present invention provides switching current device structural schematic diagram；
Fig. 8 show another embodiment of the present invention provides switching current device in spare complementary current switch module
Structural schematic diagram；
Fig. 9 show another embodiment of the present invention provides switching current module structural schematic diagram；
Figure 10 shows the current mode number of the switching current module with Background calibration function of one embodiment of the invention offer
The structural schematic diagram of mode converter；
Figure 11 show another embodiment of the present invention provides the switching current module with Background calibration function current mode
The structural schematic diagram of digital analog converter；
Figure 12 shows the current mode number of the switching current module with front desk correction function of one embodiment of the invention offer
The structural schematic diagram of mode converter；
Figure 13 show another embodiment of the present invention provides the switching current module with front desk correction function current mode
The structural schematic diagram of digital analog converter.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiments of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill people
Member's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
Fig. 5 is the structural schematic diagram for the switching current device that one embodiment of the invention provides, referring to Fig. 5, the switching current
Device, comprising: complementary current switch module to be corrected and correcting circuit module；
Correcting circuit module includes: comparator, Corrective control unit and differential switch gating control cells；
Complementary current switch module to be corrected includes: subnumber mode converter, the first current source, the second current source, and first opens
Close unit and second switch unit；
The output end of complementary current switch module to be corrected and the input terminal of comparator connect, the output end of comparator and school
The input terminal of positive control unit connects, and the output end of Corrective control unit is controlled with subnumber mode converter and differential switch gating respectively
Unit connection processed, differential-strobe control unit are connect with first switch unit and second switch unit respectively；
Subnumber mode converter is connect with the first current source, and first switch unit is connected to the first current source and complementation to be corrected
Between the output end of current switch module, second switch unit is connected to the second current source and complementary current switch module to be corrected
Output end between；
Comparator, the current value for receiving and the output end of complementary current switch module more to be corrected exports, and will
Comparison result is sent to Corrective control unit；
Corrective control unit controls signal for generating size of current according to comparison result, and size of current is controlled and is believed
Number it is sent to subnumber mode converter, so that subnumber mode converter, which controls signal according to size of current, controls the defeated of the first current source
Out；
Differential switch gating control cells, for receiving complementary electrical flow control signals, and according to complementary electrical flow control signals
Control first switch unit and second switch unit.
It should be noted that switch unit is arranged between output end and current source the present invention, it is to inhibit first
Current value error caused by the mismatch of switch unit and second switch unit.
Fig. 6 is the structure of the complementary current switch module to be corrected in the switching current device that one embodiment of the invention provides
Schematic diagram, referring to Fig. 6, the first switch unit in above-mentioned complementary current switch module to be corrected includes S1 and S2, and second opens
Closing unit includes S3 and S4, and the first current source is I1, and the second current source is that I2, S1 and S2 are connected between output end and I1
S3 and S4 are connected between output end and I2；
Wherein, one end of current source I1 and I2 connects fixed current potential one and fixed current potential two, the other end and switch of I1 respectively
One end of S1 and S2 is connected in nodes X 3, and the other end and switch S3 and S4 of I2 is connected in nodes X 4.
It will be appreciated that adjustable complementary current switch module under the control of input control signal, generates corresponding two groups
Electric current is exported, one group is output to the nodes X 1 in Fig. 5 from the first output end, and another group is output in Fig. 5 from second output terminal
Nodes X 2, and one end due to switch S9 is connected with nodes X 2, the positive input terminal phase of the other end and size of current comparator of S9
Even；One end of switch S10 is connected with nodes X 1, and the other end of S10 is connected with the negative input end of size of current comparator；
It is found that above scheme is by being transmitted to correcting circuit module for the electric current of complementary current switch module to be corrected, by
Correcting circuit module generates size of current and controls signal, size of current control signal is for controlling subnumber mould according to current differential
Converter makes it export the current value of default size, so that the equivalent output electric current of I1 be made to become original current value plus default
The current value of size；After the repeatedly output current value of adjustment subnumber mode converter, the electricity of the first output end and second output terminal
Flowing difference will be adjusted into preset accuracy rating；
The electric current of complementary current switch module to be corrected after correction will pass through the first current output terminal and second in Fig. 5
Current output terminal output.
The present invention generates electric current by comparing the output electric current after output switch first switch unit and second switch unit
Size controls signal, and the current output value of signal control current source is controlled according to size of current, to reach inhibition switch unit
The purpose of the mismatch of introducing can fundamentally reduce mistake compared to tradition just for the correction for drift technology of current source itself
Difference.
Fig. 7 be another embodiment of the present invention provides switching current device structural schematic diagram, referring to Fig. 7, in the present invention
Another embodiment in, in correction course, complementary current switch module to be corrected needs to disconnect output, into correcting state,
It will be exported at this time without electric current；And in order to enable current source is in correction course, electric current still is able to normally export, to realize
Correction in real time, to have better stability for the adverse circumstances in the course of work.In order to keep normal electric current to export, this
The correcting circuit module of invention further include:
Spare complementary current switch module, current output terminal, third switch unit and the 4th switch unit；
Spare complementary current switch module is connect with differential switch gating control cells, and third switch unit is connected to electric current
Between output end and complementary current switch module to be corrected, the 4th switch unit is connected to current output terminal and spare complementary current
Between switch module.
The correcting circuit module further include: the 5th switch unit and reference current source；
5th switch unit is connected between the complementary current switch module to be corrected and the comparator；
The reference current source is connected between the 5th switch unit and the comparator.Its working principles are as follows:
Firstly, S5, S6 of Corrective control unit control third switch unit are disconnected, to complementary current switching molding to be corrected
Block is corrected；Meanwhile be closed the 4th switch unit S7, S8 so that spare complementary current switch module substitute it is to be corrected
Adjustable complementary current switch module, so that normal electric current be kept to export；Be closed at S9, S10, with using comparator compare to
Correct the size of complementary current switch module and reference current ource electric current.
After the completion of correction, Corrective control unit controls S5, S6 closure, and S7, S8 are disconnected, again by adjustable complementary current
Switch module exports electric current.
Correspondingly, Corrective control unit is also used to:
Orientation output control signal is generated according to the comparison result, and the orientation is exported into control signal and is sent to difference
Switch-dividing gating control cells；
Differential switch gating control cells are also used to:
Control signal is exported according to the orientation, the complementary electrical flow control signals are sent to complementary current to be corrected and are opened
Close module or spare complementary current switch module；
It should be noted that under the action of orientation exports control signal, in correcting state, differential switch gating control
Unit will be sent to complementary electrical flow control signals spare complementary current switch module；In non-correcting state, differential switch choosing
Logical control unit will be sent to complementary electrical flow control signals complementary current switch module to be corrected.
Fig. 8 be another embodiment of the present invention provides the structure of spare complementary current switch module of switching current device show
It is intended to, referring to Fig. 8, spare complementary current switch module includes: the first output end, second output terminal, the first current source, the second electricity
Stream source, first switch unit and second switch unit；
It will be appreciated that the spare complementary current switch models in the present embodiment are the removing subnumber mould turn shown in Fig. 6
The adjustable complementary current switch module of parallel operation or other adjustable complementary current switch modules having had corrected that, herein not
Spare complementary current switch module is described in detail again.
The correcting circuit module of another embodiment of the present invention further include: the 5th switch unit and reference current source；
5th switch unit is connected between complementary current switch module and comparator to be corrected；
Reference current source is connected between the 5th switch unit and comparator.
Wherein, reference current source includes: the 5th current source and the 6th current source；
One end of 5th current source is connected between the S9 of the 5th switch unit and the positive input terminal of comparator, the other end with
Fixed current potential three connects；One end of 6th current source is connected between the S10 of the 5th switch unit and the negative input end of comparator,
The other end is connect with fixed current potential four.
Spare complementary current switch module, Corrective control unit are switched to by adjustable complementary current switch module in order to realize
It is also used to:
First switch control signal is generated according to comparison result and second switch controls signal；
First switch controls signal, for being connected to the 4th switch unit and the 5th switch unit in correcting state；Non-
When correcting state, the 4th switch unit and the 5th switch unit are disconnected；
Second switch controls signal, for disconnecting third switch unit in correcting state；In non-correcting state, even
Logical third switch unit.
In an alternative embodiment of the invention, the output end of complementary current switch module to be corrected include: the first output end and
Second output terminal；
The positive input terminal of the connection of the negative input end of first output end and comparator, second output terminal and comparator connects；
It will be appreciated that the first output end of adjustable complementary current switch module and the negative input end of comparator connect, the
The connection of the positive input terminal of two output ends and comparator；The current value that comparator positive input terminal receives is i.e. are as follows: second output terminal is defeated
Current value+I3 out, the current value that negative input end receives is i.e. are as follows: the current value+I4 of the first output end output.
Correspondingly, first switch unit, second switch unit, third switch unit, the 4th switch unit and the 5th open
Closing unit includes: first switch and the second switch；
First switch is connect with the first output end, and second switch is connect with second output terminal.
For example, first switch unit includes S1 and S2, second switch unit includes S3 and S4, and S1 is connected to the first output end
Between I1, S2 is connected between second output terminal and I1；The switch and its connection relationship that other switch units include, can join
Know according to Fig. 5, no longer explains herein.
In order to realize the function of digital-to-analogue conversion, differential switch gating control cells are also used to:
Difference control signal is generated according to complementary electrical flow control signals；
The first switch S1 and second switch unit of first switch unit are controlled according to the positive phase signals of difference control signal
Second switch S4, and according to the inversion signal of difference control signal control first switch unit second switch S2 and second open
Close the first switch S3 of unit；
Wherein, S1 and S4 Simultaneous Switching, S2 and S3 Simultaneous Switching, and S1 are not connected to simultaneously with S2.
It should be noted that according to the complementary electrical flow control signals received, by difference control signal to control electric current
It is exported from the first output end or second output terminal, and then controls the output port of multiple current switch modules, will counted with realizing
Word signal is converted to the effect of analog signal.
Fig. 9 be another embodiment of the present invention provides switching current module structural schematic diagram, referring to Fig. 9, to this
The working principle for inventing the switching current device provided is described in detail:
In correction course, Corrective control unit control switch S7, S8, S9, S10 are closed first, and S5, S6 are disconnected, at this time
Spare complementary current switch module substitutes adjustable complementary current switch module to be corrected, so that normal electric current is kept to export,
And adjustable complementary current switch module to be corrected is connected to size of current comparator by switch S9 and switch S10.
In error free situation, have:
Electric current-second output terminal electric current=I_const of first output end
That is, first output end of adjustable complementary current switch module and the current differential of second output terminal are normal when error free
Number I_const.Before not correcting, there are error I_error for the difference:
Electric current-second output terminal electric current=I_const+I_error of first output end
The purpose of correction module, which is that, is reduced to error I_error certain size or less.Its correction principle is as follows:
Firstly, Corrective control unit control differential switch gating control switch output control signal, so that adjustable complementary electrical
The state of switch S1, S2, S3, S4 in stream switch module do not change with externally input complementary electrical flow control signals.
Then, it is assumed that the first output end of adjustable complementary current switch module and the current differential of second output terminal are not present
Under error condition, current source I1 and I2 meet following relationship:
The electric current of the first output end of electric current=I4+ of I3+ second output terminal
To positive (+) the end electric current of size of current comparator are as follows: the electric current of I3+ second output terminal, bearing (-) end electric current is I4
The electric current of+the first output end, since the error of difference between the electric current of the first output end and the electric current of second output terminal exists, electricity
Flow Differential input current, that is, positive and negative terminal input total current difference of size comparator are as follows:
Electric current+I4- (electric current+I3 of second output terminal)=I_error of first output end
Size of current comparator exports corresponding control signal to Corrective control unit according to the I_error of Differential Input,
Corrective control unit controls the subnumber mode converter in adjustable complementary current switch module according to the signal, makes its output size
The electric current of I_adj, so that making the equivalent output electric current of the current source I1 in adjustable complementary current switch module becomes: I1-I_
Adj, the Differential input current of size of current comparator becomes I_error2 at this time:
Electric current+I4- (electric current+I3 of second output terminal)-I_adj=I_error-I_adj=I_ of first output end
error2
Differential input current I_error2 according to I_error the mode of action so that subnumber mode converter output electricity
Stream continues growing, and the Differential input current so as to cause size of current comparator is reduced to I_error3, so recycles, Zhi Dao electricity
The Differential input current of stream size comparator is reduced to the precision that control loop can be adjusted or less.Subnumber mode converter at this time
Output is so that difference, that is, the first output end of adjustable complementary current switch module of the electric current of nodes X 1 and nodes X 2 and the second output
Deviation between the difference and theoretical value at end is corrected.
In conclusion the present invention, which passes through, introduces compensating current element, to realize defeated to the difference in complementary current structure
The correction of error between the difference of electric current and theoretical difference out, that is, remain original complementary current structure, ensure that high frequency
While output impedance, the matching performance of current source is also improved, to improve the linearity.Simultaneously because alignment technique draws
Enter, so that the size of current source is minimized, to reduce the influence of parasitic capacitance bring, further improves output resistance
It is anti-, while the speed of circuit is also promoted.
Importantly, since the sampling of size of current comparator in correction inputs after switch unit, hence for
The mismatch that switch unit introduces can have further inhibiting effect, compared to tradition just for the correction for drift of current source itself
Technology, this alignment technique can fundamentally reduce the error adversely affected for output.
Background calibration function makes current source in correction course simultaneously, and circuit still is able to normally export, to realize
Adverse circumstances in the course of work are had better stability by correction in real time.
In order to facilitate understanding, the switching current module shown in Fig. 5 is known as the switching current module with foreground function herein,
Switching current module shown in Fig. 7 is known as the switching current module with background function；
Figure 10 is that the current mode digital-to-analogue for the switching current module with Background calibration function that one embodiment of the invention provides turns
The structural schematic diagram of parallel operation, referring to Fig.1 0, the digital analog converter, comprising: decoder and switching current array interconnected；
Switching current array includes at least one switching current device with background function；
Decoder, for the digital input signals received to be converted to difference control signal, and by difference control signal
It is sent to switching current array, so that switching current array exports mould corresponding with digital input signals according to difference control signal
Quasi- signal.
It will be appreciated that each unit of switching current array includes at least one current source and at least a pair of control signal
The switch of reverse phase；And in the switching current array, at least one unit is the switching current module shown in Fig. 7；
External digital input signal generates difference control signal by decoder, in control switch circuit to inductive switch,
To control switch current array each unit output difference electric current it is positive and negative, the electric current of switching current array output end into
The cumulative summation of row, to obtain corresponding simulation output；
It is corrected since above-mentioned switching current module has calibration function, output difference electric current and theoretical value
Deviation is controlled within certain accuracy rating.To make the precision of entire digital analog converter be improved；In addition, due to figure
The digital analog converter of the characteristic of switching current device shown in 7, the type can complete digital-to-analogue conversion process while correction.
Figure 11 be another embodiment of the present invention provides the switching current module with Background calibration function current mode digital-to-analogue
The structural schematic diagram of converter, referring to Fig.1 1, digital analog converter and the digital analog converter phase shown in Figure 10 disclosed in the present embodiment
Than difference place is that the switching current array of the present embodiment includes: sharing module group；
Sharing module group includes: multiple switch current module, switching switch and a correcting circuit module；
Switching switch is separately connected multiple switch current module and correction module；
Correction module, for being corrected respectively to each switching current module by switching switch；
Wherein, sharing module group is the shared part of module of the switching current module in figure with Background calibration, is removed altogether
Other the switching current modules with Background calibration for enjoying module group are non-shared part module.
It will be appreciated that multiple switch current module share one group of correcting circuit module, comprising size of current comparator with
And corresponding reference current source, Corrective control unit etc..The multiple groups switching current module for sharing the same correcting circuit, a certain
Moment only corrects one group of switching current module therein, by the first current output terminal of switching current module to be corrected and
The output electric current of two current output terminals is continued pair by two input terminals of switching to size of current comparator after having corrected
Next circuit module is corrected.By the correction of multiple clock cycle, to complete the correction in entire complementary current source.It is logical
Module reuse is crossed, to reduce the area of chip, and then saves power consumption.
Figure 12 is that the current mode digital-to-analogue for the switching current module with front desk correction function that one embodiment of the invention provides turns
The structural schematic diagram of parallel operation, referring to Fig.1 2, band Background calibration disclosed in the digital analog converter and Figure 10 with front desk correction function
Switching current module current mode digital-to-analog converter the difference is that:
Switching current array in this digital analog converter includes at least one switching current device shown in fig. 5.
Figure 13 be another embodiment of the present invention provides the switching current module with front desk correction function current mode digital-to-analogue
The structural schematic diagram of converter, referring to Fig.1 digital analog converter disclosed in 3, with Figure 11 the difference is that, sharing module
Switching current module in group is the switching current module with front desk correction；
It is further to note that characteristic of the digital analog converter of both types by institute's belt switch current device, gram
It makes, spare complementary current switch module is eliminated in the switching current module with front desk correction function, to save
Spare module bring area consumption, but in switching current module correction course, switching current module can not be exported normally, electricity
Stream correction course need to carry out on foreground.It equally include switching current array and decoding in front desk correction digital analog converter
Device, and at least one unit is the switching current module with front desk correction function as described in this patent in switch arrays.
This digital analog converter with front desk correction function with Background calibration function digital analog converter it is maximum the difference is that,
Digital analog converter with Background calibration function is in correction course, using one group of spare complementary current switch module substitution
The complementary current switch module of correction is exported, so as to allow digital analog converter to keep normal work during correction
Make, realizes real time correction.
Although the embodiments of the invention are described in conjunction with the attached drawings, but those skilled in the art can not depart from this hair
Various modifications and variations are made in the case where bright spirit and scope, such modifications and variations are each fallen within by appended claims
Within limited range.
Claims (10)
1. a kind of switching current device characterized by comprising complementary current switch module to be corrected and correcting circuit module；
The correcting circuit module includes: comparator, Corrective control unit and differential switch gating control cells；
The complementary current switch module to be corrected includes: subnumber mode converter, the first current source, the second current source, and first opens
Close unit and second switch unit；
The output end of the complementary current switch module to be corrected is connect with the input terminal of the comparator, the comparator it is defeated
Outlet is connect with the input terminal of the Corrective control unit, and the output end of the Corrective control unit turns with the subnumber mould respectively
Parallel operation is connected with the differential switch gating control cells, the differential switch gating control cells respectively with the first switch
Unit is connected with the second switch unit, and the Corrective control unit generates orientation output control signal according to comparison result,
And the orientation is exported into control signal and is sent to the differential switch gating control cells, the differential switch gating control is single
Member exports control signal according to the orientation, and complementary electrical flow control signals are sent to the complementary current switch module to be corrected
Or spare complementary current switch module；
The subnumber mode converter is connect with first current source, and the first switch unit is connected to first current source
Between the output end of the complementary current switch module to be corrected, the second switch unit is connected to second current source
Between the output end of the complementary current switch module to be corrected；
The comparator, the current value for receiving and the output end of the complementary current switch module to be corrected exports,
And comparison result is sent to the Corrective control unit；
The Corrective control unit controls signal for generating size of current according to the comparison result, and the electric current is big
Small control signal is sent to the subnumber mode converter, so that the subnumber mode converter controls signal according to the size of current
Control the output of first current source；
The differential switch gating control cells are controlled for receiving complementary electrical flow control signals, and according to the complementary current
Signal controls the first switch unit and the second switch unit.
2. the apparatus according to claim 1, which is characterized in that the correcting circuit module further include: spare complementary current
Switch module, current output terminal, third switch unit and the 4th switch unit；
The spare complementary current switch module is connect with the differential switch gating control cells, and the third switch unit connects
It connects between the current output terminal and the complementary current switch module to be corrected, the 4th switch unit is connected to described
Between current output terminal and the spare complementary current switch module.
3. the apparatus of claim 2, which is characterized in that the Corrective control unit is also used to:
Orientation output control signal is generated according to the comparison result, and orientation output control signal is sent to difference and is opened
Close gating control cells；
Correspondingly, the differential switch gating control cells are also used to:
Control signal is exported according to the orientation, the complementary electrical flow control signals are sent to complementary current switching molding to be corrected
Block or spare complementary current switch module.
4. the apparatus according to claim 1, which is characterized in that the correcting circuit module further include: the 5th switch unit
And reference current source；
5th switch unit is connected between the complementary current switch module to be corrected and the comparator；
The reference current source is connected between the 5th switch unit and the comparator.
5. device according to claim 4, which is characterized in that the reference current source includes: the 5th current source and the 6th
Current source；
5th current source is connected between the 5th switch unit and the positive input terminal of the comparator, the 6th electricity
Stream source is connected between the 5th switch unit and the negative input end of the comparator.
6. device according to claim 4, which is characterized in that the Corrective control unit is also used to:
The correcting circuit module further include: spare complementary current switch module, current output terminal, third switch unit and the 4th
Switch unit；
The spare complementary current switch module is connect with the differential switch gating control cells, and the third switch unit connects
It connects between the current output terminal and the complementary current switch module to be corrected, the 4th switch unit is connected to described
Between current output terminal and the spare complementary current switch module；
First switch control signal is generated according to comparison result and second switch controls signal；
The first switch controls signal, in correcting state, being connected to the 4th switch unit and the 5th switch
Unit；In non-correcting state, the 4th switch unit and the 5th switch unit are disconnected；
The second switch controls signal, for disconnecting the third switch unit in correcting state；In non-correcting state
When, it is connected to the third switch unit.
7. device according to claim 4, which is characterized in that the output end packet of the complementary current switch module to be corrected
It includes: the first output end and second output terminal；
The correcting circuit module further include: spare complementary current switch module, current output terminal, third switch unit and the 4th
Switch unit；
The spare complementary current switch module is connect with the differential switch gating control cells, and the third switch unit connects
It connects between the current output terminal and the complementary current switch module to be corrected, the 4th switch unit is connected to described
Between current output terminal and the spare complementary current switch module；
First output end is connect with the negative input end of the comparator, and the second output terminal is just defeated with the comparator
Enter end connection；
Correspondingly, the first switch unit, the second switch unit, the third switch unit, the 4th switch are single
First and described 5th switch unit includes: first switch and the second switch；
The first switch is connect with the first output end, and the second switch is connect with the second output terminal.
8. device according to claim 7, which is characterized in that the differential switch gating control cells are also used to:
Difference control signal is generated according to the complementary electrical flow control signals；
The first switch of the first switch unit and described second is controlled according to the positive phase signals of the difference control signal to open
The second switch of unit is closed, and controls the second of the first switch unit according to the inversion signal of the difference control signal and opens
Close the first switch with the second switch unit.
9. a kind of digital analog converter characterized by comprising decoder and switching current array interconnected；
The switching current array includes at least one switching current device as described in claim any one of 1-8；
The decoder for the digital input signals received to be converted to difference control signal, and the difference is controlled
Signal is sent to the switching current array so that the switching current array according to the difference control signal export with it is described
The corresponding analog signal of digital input signals.
10. digital analog converter according to claim 9, which is characterized in that the switching current array includes: sharing module
Group；
The sharing module group includes: multiple switch current module, switching switch and a correcting circuit module；
The switching switch is separately connected the multiple switching current module and the correcting circuit module；
The correcting circuit module, for being corrected respectively to each switching current module by switching switch.
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