CN106856405A - 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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- CN106856405A CN106856405A CN201510896098.8A CN201510896098A CN106856405A CN 106856405 A CN106856405 A CN 106856405A CN 201510896098 A CN201510896098 A CN 201510896098A CN 106856405 A CN106856405 A CN 106856405A
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Abstract
The invention discloses a kind of switching current device and the digital analog converter based on 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 weighted-voltage D/A converter, the first current source, the second current source, first switch unit and second switch unit；Comparator is connected with the output end and Corrective control unit of complementary current switch module to be corrected respectively, Corrective control unit is connected with subnumber weighted-voltage D/A converter and differential switch gating control cells respectively, and differential-strobe control unit is connected 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 current by suppressing the mismatch that switch element is introduced.
Description
Technical field
The present invention relates to d convertor circuit technical field, and in particular to a kind of switching current dress
Put and the digital analog converter based on the device.
Background technology
Digital analog converter (DAC) as between numeric field and analog domain change important bridge,
The important role in signal transacting and the communications field.With in modern communicationses, information content is carried
Height, the speed of logarithm weighted-voltage D/A converter has requirement higher.Simultaneously because the multiplexing of frequency spectrum, makes
Simultaneous signal spectrum scope is wider in obtaining single channel, is to reduce signal in different frequency range
Interference, while reducing the interference of the harmonic wave of non-linear introducing, it is desirable to which digital analog converter has higher
The linearity.The linearity of DAC is generally described using SFDR (SFDR),
SFDR is defined as in the frequency band range that output is concerned about, the harmonic wave of signal energy and energy maximum
The ratio between energy.It is current application field that SFDR higher is reached in broader frequency band range
The new performance requirement that development logarithm weighted-voltage D/A converter is proposed, be also ongoing research area focus it
One.
In high-speed A/D converter, current mode digital-to-analog converter is because it is than other structures
DAC speed is faster, low in energy consumption, and carrying load ability is strong, thus is widely adopted.Fig. 1
It is the basic structure of current mode digital-to-analog converter, reference picture 1, current mode digital-to-analog converter is included
One group of current source permutation and a pair of switches unit being connected with each current source.Input numeral
The break-make of Signal-controlled switch unit, so as to control the current direction of each current source specifically defeated
Go out end, the electric current from current source carries out addition summation in two output ends, two output ends
Difference is the corresponding analog output of supplied with digital signal.
In traditional current mode DAC, influence the principal element of SFDR performances probably can be with
It is divided into following two major class：Static implicit method and dynamic factor.Wherein Static implicit method refers mainly to current source
Matching error cause output end each input digital code conversion output stabilization when exist with
Error between ideal output.Resistance drop causes same cabling each point in circuit on cabling simultaneously
The graded of voltage, and the influence that thermograde is brought can also introduce current source reality output
Error between being exported with ideal, when supplied with digital signal is related to these output errors, just
The harmonic wave related to input signal can be introduced so as to reduce SFDR in output end.In order to reduce electricity
Stream source matching error, simplest method is to use bigger transistor area to improve matching journey
Degree, but the increase of transistor area will cause the increase of parasitic capacitance, so as to limit DAC
Speed.And increasing the area of current source merely can not improve cabling pressure drop and temperature ladder
The brought error of degree, is this more effectively and more essential method is to use alignment technique,
Directly within the accuracy rating by the output calibration of current source needed for.
Influence the dynamic factor of SFDR to be mainly to switch with the digital word of digital analog converter
Cheng Xiangguan.In digital word handoff procedure, due to time order error, the power of drive signal,
And the mismatch of switching tube etc. can all be introduced into the non-ideal output in handoff procedure, so as to introduce hair
Thorn.So as to reduce the SFDR of output signal.In addition, finite output impedance is that limitation is whole
The key factor of individual DAC SFDR in high frequency, Fig. 2 is current source output impedance and SFDR
Between relation schematic diagram, reference picture 2 understand, as the increase SFDR of output impedance is able to
Improve.Because output impedance is finite value, and due to the influence of parasitic capacitance, cause output
There is capacitive composition in impedance, in high frequency, output impedance further deteriorates.
Fig. 3 is the structure and schematic diagram of complementary electrical flow pattern digital analog converter, and reference picture 3 is existing
Technology proposes a kind of complementary electrical flow pattern digital analog converter.Its it is critical only that a pair of complementary switch and
The addition of respective complementary electric current, in this configuration, to any one current source and switch element
For, under the control of any switch controlling signal, two output ends of the unit are deposited
In electric current output, but the difference of output keeps certain.When the electric current of two-way output meets certain
Proportionate relationship when, the more traditional structure of effective output impedance is greatly improved, so as to carry
SFDR high.
The correction of current source is the effective means of the static accuracy for improving current mode digital-to-analog converter.
Fig. 4 is the structure and schematic diagram of the current mode digital-to-analog converter with calibration function, reference picture 4,
In trimming process, output and the reference current source of adjustable current source are compared, and comparator is defeated
The error controling signal for going out controls the size of current of adjustable current source, until adjustable current source reaches
Certain accuracy rating, the regulated power supply of switch switching accordingly is exported after correction is finished.Phase
In the way of increasing current source area to improve matching than tradition, correction more ensure that current source
Precision, it is more efficient in terms of the change of resistance thermograde and cabling pressure drop, while more supernumerary segment
Save area.
In due to conventional correction, all only existing single channel current source needs correction, and in complementary electrical
In flow structure, last output current is two differences of current source, that is to say, that opened
There is electric current in the two-way complementary output for closing control, and its difference is only the output valve of theory.
And due to the mismatch of the switch element for controlled output, cause two in complementary structure
When individual current source difference is theoretical difference, the difference current of its reality output still deposits deviation.
The content of the invention
For defect of the prior art, the invention provides a kind of switching current device and it is based on
The digital analog converter of the device, the switching current device can effectively suppress switch element introducing
Mismatch, the correction for drift technology compared to tradition just for current source in itself, the present invention can be from
Fundamentally reduce error.
The present invention proposes a kind of switching current device, it is characterised in that including complementation to be corrected
Current switch module and correcting circuit module；
The correcting circuit module includes：The choosing of comparator, Corrective control unit and differential switch
Logical control unit；
The complementary current switch module to be corrected includes：Subnumber weighted-voltage D/A converter, the first current source,
Second current source, first switch unit and second switch unit；
The output end of the complementary current switch module to be corrected and the input of the comparator
Connection, the output end of the comparator is connected with the input of the Corrective control unit, described
The output end of Corrective control unit is selected with the subnumber weighted-voltage D/A converter and the differential switch respectively
Logical control unit connection, the differential-strobe control unit respectively with the first switch unit and
The second switch unit connection；
The subnumber weighted-voltage D/A converter is connected with first current source, and the first switch unit connects
It is connected between the output end of first current source and the complementary current switch module to be corrected,
The second switch unit is connected to second current source and the complementary current to be corrected is opened
Between the output end of pass module；
The comparator, for receive and the relatively complementary current switch module to be corrected it is defeated
Go out the current value of end output, and comparative result is sent to the Corrective control unit；
The Corrective control unit, for generating size of current control letter according to the comparative result
Number, and the size of current control signal is sent to the subnumber weighted-voltage D/A converter, so that described
Subnumber weighted-voltage D/A converter controls the defeated of first current source according to the size of current control signal
Go out；
The differential switch gating control cells, for receiving complementary current control signal, and root
The first switch unit and the second switch list are controlled according to the complementary current control signal
Unit.
Optionally, the correcting circuit module also includes：Standby complementary current switch module, electricity
Stream output end, the 3rd switch element and the 4th switch element；
The standby complementary current switch module is connected with the differential switch gating control cells,
3rd switch element is connected to the current output terminal and the complementary current to be corrected is opened
Close module between, the 4th switch element be connected to the current output terminal and it is described it is standby mutually
Between benefit current switch module.
Optionally, the Corrective control unit is additionally operable to：
According to comparative result generation orientation output control signal, and the orientation output is controlled
Signal processed is sent to differential switch gating control cells；
Correspondingly, the differential switch gating control cells are additionally operable to：
According to the orientation output control signal, the complementary current control signal is sent to treating
Correction complementary current switch module or standby complementary current switch module.
Optionally, the correcting circuit module also includes：5th switch element and reference current source；
5th switch element is connected to the complementary current switch module to be corrected and described
Between comparator；
The reference current source is connected between the 5th switch element and the comparator.
Optionally, the reference current source includes：5th current source and the 6th current source；
It is just defeated with the comparator that 5th current source is connected to the 5th switch element
Enter between end, the 6th current source is connected to the 5th switch element and the comparator
Between negative input end.
Optionally, the Corrective control unit is additionally operable to：
First switch control signal and second switch control signal are generated according to comparative result；
The first switch control signal, in correcting state, connecting the 4th switch
Unit and the 5th switch element；In non-correcting state, the 4th switch element is disconnected
With the 5th switch element；
The second switch control signal, in correcting state, disconnecting the 3rd switch
Unit；In non-correcting state, the 3rd switch element is connected.
Optionally, the output end of the complementary current switch module to be corrected includes：First output
End and the second output end；
First output end is connected with the negative input end of the comparator, second output end
Positive input terminal with the comparator is connected；
Correspondingly, the first switch unit, the second switch unit, the 3rd switch
Unit, the 4th switch element and the 5th switch element include：First switch and
Second switch；
The first switch is connected with the first output end, and the second switch and described second is exported
End connection.
Optionally, the differential switch gating control cells are additionally operable to：
Difference control signal is generated according to the complementary current control signal；
Positive phase signals according to the difference control signal control the of the first switch unit
The second switch of one switch and the second switch unit, and according to the difference control signal
Inversion signal controls the second switch and the second switch unit of the first switch unit
First switch.
The invention allows for a kind of digital analog converter, it is characterised in that including：It is connected with each other
Decoder and switching current array；
The switching current array includes at least one above-mentioned switching current device；
The decoder, the digital input signals for that will receive are converted to difference control signal,
And send to the switching current array difference control signal, so that the switching current
Array corresponding with the digital input signals simulates letter according to difference control signal output
Number.
Optionally, the switching current array includes：Sharing module group；
The sharing module group includes：Multiple switch current module, switching switch and a correction
Circuit module；
The switching switch connects the multiple switching current module and the correction module respectively；
The correction module, for being entered to each switching current module respectively by the switching switch
Row correction.
As shown from the above technical solution, switching current device proposed by the present invention, by relatively more defeated
The output current generation size of current control signal gone out after switch element, and according to size of current control
The current output value in signal control electric current source processed, the mismatch that switch element is introduced is suppressed to reach
Purpose, the correction for drift technology compared to tradition just for current source in itself, can be fundamentally
Reduce error.
Brief description of the drawings
The features and advantages of the present invention can be more clearly understood from by reference to accompanying drawing, accompanying drawing is to show
Meaning property and should not be construed as carrying out the present invention any limitation, in the accompanying drawings：
Fig. 1 shows the basic structure of current mode digital-to-analog converter；
Fig. 2 shows the relation schematic diagram 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 representation of the switching current device that one embodiment of the invention is provided；
Fig. 6 shows the complementation to be corrected in the switching current device that one embodiment of the invention is provided
The structural representation of current switch module；
Fig. 7 shows the structural representation of the switching current device that another embodiment of the present invention is provided；
Fig. 8 shows the standby complementation in the switching current device that another embodiment of the present invention is provided
The structural representation of current switch module；
Fig. 9 shows the structural representation of the switching current module that another embodiment of the present invention is provided；
Figure 10 shows the switching current with Background calibration function that one embodiment of the invention is provided
The structural representation of the current mode digital-to-analog converter of module；
Figure 11 shows the electricity of the switch with Background calibration function that another embodiment of the present invention is provided
The structural representation of the current mode digital-to-analog converter of flow module；
Figure 12 shows the switching current with front desk correction function that one embodiment of the invention is provided
The structural representation of the current mode digital-to-analog converter of module；
Figure 13 shows the electricity of the switch with front desk correction function that another embodiment of the present invention is provided
The structural representation of the current mode digital-to-analog converter of flow module.
Specific embodiment
To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below will knot
Close the embodiment of the present invention in accompanying drawing, the technical scheme in the embodiment of the present invention is carried out it is clear,
It is fully described by, it is clear that described embodiment is a part of embodiment of the invention, without
It is whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not having
There is the every other embodiment obtained on the premise of making creative work, belong to the present invention
The scope of protection.
The structural representation of the switching current device that Fig. 5 is provided for one embodiment of the invention, reference
Fig. 5, the switching current device, including：Complementary current switch module to be corrected and correcting circuit
Module；
Correcting circuit module includes：The gating control of comparator, Corrective control unit and differential switch
Unit processed；
Complementary current switch module to be corrected includes：Subnumber weighted-voltage D/A converter, the first current source,
Two current sources, first switch unit and second switch unit；
The output end of complementary current switch module to be corrected is connected with the input of comparator, compares
The output end of device is connected with the input of Corrective control unit, the output end point of Corrective control unit
It is not connected with subnumber weighted-voltage D/A converter and differential switch gating control cells, differential-strobe control unit
It is connected with first switch unit and second switch unit respectively；
Subnumber weighted-voltage D/A converter is connected with the first current source, and first switch unit is connected to the first electric current
Between the output end of source and complementary current switch module to be corrected, second switch unit is connected to
Between the output end of two current sources and complementary current switch module to be corrected；
Comparator, for receiving and the relatively output end output of complementary current switch module to be corrected
Current value, and comparative result is sent to Corrective control unit；
Corrective control unit, for generating size of current control signal according to comparative result, and will
Size of current control signal is sent to subnumber weighted-voltage D/A converter, so that subnumber weighted-voltage D/A converter is according to electric current
Size control signal controls the output of the first current source；
Differential switch gating control cells, for receiving complementary current control signal, and according to mutual
Mend current controling signal control first switch unit and second switch unit.
It should be noted that be arranged on switch element between output end and current source by the present invention,
It is that the current value caused to suppress the mismatch of first switch unit and second switch unit is missed
Difference.
Complementary current to be corrected in the switching current device that Fig. 6 is provided for one embodiment of the invention
The structural representation of switch module, reference picture 6, above-mentioned complementary current switch module to be corrected
In first switch unit include S1 and S2, second switch unit include S3 and S4, first electricity
Stream source is I1, and the second current source is I2, S1 and S2 and is connected to S3 between output end and I1
And S4 is connected between output end and I2；
Wherein, one end of current source I1 and I2 connects fixed potential one and fixed potential two, I1 respectively
The other end be connected in nodes X 3 with one end of switch S1 and S2, the other end and the switch S3 of I2
Nodes X 4 is connected in S4.
It will be appreciated that adjustable complementary current switch module is under the control of input control signal,
Corresponding two groups of output currents are generated, one group exports to the nodes X 1 in Fig. 5 from the first output end,
Another group from the second output end export to the nodes X 2 in Fig. 5, and due to switch S9 one end with
Nodes X 2 is connected, and the other end of S9 is connected with the positive input terminal of size of current comparator；Switch
One end of S10 is connected with nodes X 1, the other end of S10 and the negative input of size of current comparator
End is connected；
Understand, such scheme is streamed to school by by the electricity of complementary current switch module to be corrected
Positive circuit module, by correcting circuit module according to current differential, generates size of current control signal,
Size of current control signal is used to control subnumber weighted-voltage D/A converter, makes the electric current of the default size of its output
Value, so that the equivalent output current of I1 is changed into the current value that original current value adds default size；
After the repeatedly output current value of adjustment subnumber weighted-voltage D/A converter, the first output end and the second output end
Current differential will adjust in default accuracy rating；
The electric current of the complementary current switch module to be corrected after correction is by by the first electricity in Fig. 5
Stream output end and the output of the second current output terminal.
The present invention is defeated after comparing output switch first switch unit and second switch unit
Go out electric current generation size of current control signal, and according to size of current control signal control electric current source
Current output value, with reach suppress switch element introduce mismatch purpose, compared to tradition only
For current source correction for drift technology in itself, error can be fundamentally reduced.
The structural representation of the switching current device that Fig. 7 is provided for another embodiment of the present invention, ginseng
According to Fig. 7, in another embodiment of the invention, in trimming process, complementary current to be corrected
Switch module needs to disconnect output, into correcting state, will now be exported without electric current；And be
Current source is caused in trimming process, electric current remains able to normal output, so as to realize in real time
Correction, have more preferable stability with for the adverse circumstances in the course of work.In order to keep just
Normal electric current output, correcting circuit module of the invention also includes：
Standby complementary current switch module, current output terminal, the 3rd switch element and the 4th switch
Unit；
Standby complementary current switch module is connected with differential switch gating control cells, the 3rd switch
Unit is connected between current output terminal and complementary current switch module to be corrected, and the 4th switch is single
Unit is connected between current output terminal and standby complementary current switch module.
Its operation principle is as follows：
First, Corrective control unit controls S5, S6 of the 3rd switch element to disconnect, to treat school
Positive complementary current switch module is corrected；Meanwhile, S7, S8 of the 4th switch element are closed,
So that standby complementary current switch module substitutes adjustable complementary current switch module to be corrected, from
And keep normal electric current to export.
After the completion of correction, Corrective control unit control S5, S6 closure, S7, S8 disconnect,
With again by adjustable complementary current switch module output current.
Correspondingly, Corrective control unit is additionally operable to：
According to comparative result generation orientation output control signal, and the orientation output is controlled
Signal processed is sent to differential switch gating control cells；
Differential switch gating control cells are additionally operable to：
According to the orientation output control signal, the complementary current control signal is sent to treating
Correction complementary current switch module or standby complementary current switch module；
It should be noted that in the presence of output control signal is oriented, in correcting state,
Differential switch gating control cells will be sent complementary current control signal to standby complementary current
Switch module；In non-correcting state, differential switch gating control cells will be complementary current control
Signal processed is sent to complementary current switch module to be corrected.
Fig. 8 is opened for the standby complementary current of the switching current device that another embodiment of the present invention is provided
The structural representation of module is closed, reference picture 8, standby complementary current switch module includes：First
Output end, the second output end, the first current source, the second current source, first switch unit and
Two switch elements；
It will be appreciated that the standby complementary current switch models in the present embodiment are Fig. 6 and show
Removing subnumber weighted-voltage D/A converter adjustable complementary current switch module, or other have corrected that
Good adjustable complementary current switch module, is no longer carried out to standby complementary current switch module herein
Describe in detail.
The correcting circuit module of another embodiment of the present invention also includes：5th switch element and reference
Current source；
5th switch element is connected between complementary current switch module to be corrected and comparator；
Reference current source is connected between the 5th switch element and comparator.
Wherein, reference current source includes：5th current source and the 6th current source；
One end of 5th current source is connected to the S9 of the 5th switch element and the positive input of comparator
Between end, the other end is connected with fixed potential three；One end of 6th current source is connected to the 5th and opens
Close between the S10 and the negative input end of comparator of unit, the other end is connected with fixed potential four.
In order to realize switching to standby complementary current switching molding by adjustable complementary current switch module
Block, Corrective control unit is additionally operable to：
First switch control signal and second switch control signal are generated according to comparative result；
First switch control signal, in correcting state, the 4th switch element of connection and the
Five switch elements；In non-correcting state, the 4th switch element and the 5th switch element are disconnected；
Second switch control signal, in correcting state, disconnecting the 3rd switch element；
During non-correcting state, the 3rd switch element is connected.
In an alternative embodiment of the invention, the output end of complementary current switch module to be corrected includes：
First output end and the second output end；
First output end is connected with the negative input end of comparator, and the second output end is with comparator just
Input is connected；
It will be appreciated that the first output end of adjustable complementary current switch module is negative with comparator
Input is connected, and the second output end is connected with the positive input terminal of comparator；Comparator positive input terminal
The current value for receiving is：Current value+the I3 of the second output end output, negative input end is received
To current value be：Current value+the I4 of the first output end output.
Correspondingly, first switch unit, second switch unit, the 3rd switch element, the 4th open
Closing unit and the 5th switch element includes：First switch and second switch；
First switch is connected with the first output end, and second switch is connected with the second output end.
For example, first switch unit includes S1 and S2, second switch unit includes S3 and S4,
S1 is connected between the first output end and I1, and S2 is connected between the second output end and I1；Other
Switch and its annexation that switch element includes, can refer to Fig. 5 and know, no longer enter herein
Row is explained.
In order to realize the function of digital-to-analogue conversion, differential switch gating control cells are additionally operable to：
Difference control signal is generated according to complementary current control signal；
Positive phase signals according to difference control signal control the first switch S1 of first switch unit
With the second switch S4 of second switch unit, and according to the inversion signal of difference control signal control
The second switch S2 of the first switch unit and first switch S3 of second switch unit；
Wherein, when S1 and S4 Simultaneous Switchings, S2 and S3 Simultaneous Switchings, and S1 are different with S2
Connection.
It should be noted that according to the complementary current control signal for receiving, by difference control
Signal is exported with control electric current from the first output end or the second output end, and then controls multiple electricity
The output port of switch module is flowed, to realize converting digital signals into the effect of analog signal.
The structural representation of the switching current module that Fig. 9 is provided for another embodiment of the present invention, under
Face reference picture 9, the operation principle of the switching current device provided the present invention is described in detail：
In trimming process, Corrective control unit controlling switch S7, S8, S9, S10 are closed first
Close, S5, S6 disconnect, now standby complementary current switch module substitutes adjustable complementation to be corrected
Current switch module, so that keep normal electric current to export, and adjustable complementary current to be corrected
Switch module is connected to size of current comparator by switching S9 and switch S10.
In the case of error free, have：
Electric current=the I_const of the output end of electric current-the second of the first output end
That is, first output end and the second output end of adjustable complementary current switch module when error free
Current differential be constant I_const.Before not correcting, there is error I_error in the difference:
Electric current=the I_const+I_error of the output end of electric current-the second of the first output end
The purpose of correction module is that and error I_error is reduced to below certain size.Its
Correction principle is as follows：
First, Corrective control unit control differential switch gating controlling switch output control signal,
So that the state of the switch S1, S2, S3, S4 in adjustable complementary current switch module is not with outer
Portion input complementary current control signal and change.
Then, it is assumed that the first output end of adjustable complementary current switch module and the second output end
In the absence of under error condition, current source I1 and I2 meet following relation to current differential：
The electric current of the output ends of electric current=I4+ first of the output ends of I3+ second
So as to just (+) end electric current of size of current comparator is：The electric current of the output ends of I3+ second,
Negative (-) end electric current is the electric current of the output ends of I4+ first, due to the electric current of the first output end and the
The error of difference is present between the electric current of two output ends, the Differential Input electricity of size of current comparator
Stream is that the difference of positive and negative terminal input total current is：
Electric current+I4- (electric current+I3 of the second output end)=I_error of first output end
Size of current comparator exports corresponding control signal and arrives according to the I_error of Differential Input
Corrective control unit, Corrective control unit controls adjustable complementary current switch module according to the signal
In subnumber weighted-voltage D/A converter, make its output size be I_adj electric current so that adjustable complementary electrical
The equivalent output current of the current source I1 in stream switch module is changed into：I1-I_adj, now electric current is big
The Differential input current of small comparator is changed into I_error2：
Electric current+I4- (the electric currents of the second output end of the first output end
+ I3)-I_adj=I_error-I_adj=I_error2
Differential input current I_error2 according to I_error the mode of action so that sub- digital-to-analogue conversion
The output current of device continues to increase, so as to the Differential input current for causing size of current comparator drops
As little as I_error3, so circulation, until the Differential input current of size of current comparator is reduced to
Below the precision that control loop can be adjusted.The now output of subnumber weighted-voltage D/A converter causes node
The difference of the electric current of X1 and nodes X 2 is the adjustable output end of complementary current switch module first and
Deviation between the difference and theoretical value of two output ends is corrected.
In sum, it is of the invention by introducing compensating current element, it is achieved thereby that to complementary current
The correction of the error between the difference of the differential output current in structure and theoretical difference, that is, retain
Original complementary current structure, it is ensured that while high frequency output impedance, also improve electric current
The matching performance in source, so as to improve the linearity.Simultaneously because the introducing of alignment technique so that
The size of current source is minimized, and so as to reduce the influence that parasitic capacitance is brought, further carries
Output impedance high, while the speed of circuit is also lifted.
Importantly, because the sampling of size of current comparator in correction is input into switch element
Afterwards, the mismatch for being introduced hence for switch element can have further inhibitory action, compare
Correction for drift technology of the tradition just for current source in itself, this alignment technique can be fundamentally
Reduce the error adversely affected for output.
Background calibration function causes current source in trimming process simultaneously, and circuit is remained able to normally
Output, so as to realize correction in real time, has preferably steady for the adverse circumstances in the course of work
It is qualitative.
Understand for convenience, the switching current module shown in Fig. 5 is referred to as band foreground function herein
Switching current module, the switching current module shown in Fig. 7 is referred to as the switch with background function
Current module；
The switching current module with Background calibration function that Figure 10 is provided for one embodiment of the invention
Current mode digital-to-analog converter structural representation, reference picture 10, the digital analog converter, including：
The decoder and switching current array of interconnection；
Switching current array includes at least one switching current device with background function；
Decoder, the digital input signals for that will receive are converted to difference control signal, and
Difference control signal is sent to switching current array, so that switching current array is according to difference control
Signal output processed analog signal corresponding with digital input signals.
It will be appreciated that each unit of switching current array is including at least one current source and extremely
The switch of few a pair of control signal inversion；And in the switching current array, at least one list
Unit is the switching current module shown in Fig. 7；
External digital input signal produces difference control signal, controlling switch circuit by decoder
In to inductive switch so that each unit output difference electric current of controlling switch current array is just
Negative, the electric current of switching current array carries out cumulative summation in output end, so as to obtain corresponding mould
Intend output；
Because above-mentioned switching current module has calibration function, corrected, its output difference
Electric current is controlled within certain accuracy rating with the deviation of theoretical value.So that whole digital-to-analogue
The precision of converter is improved；Further, since the characteristic of the switching current device shown in Fig. 7,
The digital analog converter of the type can complete digital-to-analogue conversion process while correction.
The switching current mould with Background calibration function that Figure 11 is provided for another embodiment of the present invention
The structural representation of the current mode digital-to-analog converter of block, reference picture 11, number disclosed in the present embodiment
Compared with the digital analog converter shown in Figure 10, distinguish part is weighted-voltage D/A converter, the present embodiment
Switching current array includes：Sharing module group；
Sharing module group includes：Multiple switch current module, switching switch and a correcting circuit
Module；
Switching switch connects multiple switch current module and correction module respectively；
Correction module, for being corrected to each switching current module respectively by switching switch；
Wherein, sharing module group is the shared portion of the switching current module with Background calibration in figure
Sub-module, other switching current modules with Background calibration for removing sharing module group are non-co-
Enjoy part of module.
It will be appreciated that multiple switch current module shares one group of correcting circuit module, comprising electricity
Stream size comparator and corresponding reference current source, Corrective control unit etc..It is shared same
Multigroup switching current module of correcting circuit, at a time, only corrects one group of switch therein
Current module, first current output terminal and the second electric current of switching current module to be corrected is defeated
The output current for going out end is switched to two inputs of size of current comparator, correction by switch
Continue to be corrected next circuit module after complete.By the correction of multiple clock cycle, from
And complete the correction in whole complementary current source.By module reuse, so as to reduce the face of chip
Product, and then save power consumption.
The switching current module with front desk correction function that Figure 12 is provided for one embodiment of the invention
Current mode digital-to-analog converter structural representation, reference picture 12, this is with front desk correction function
The current mode digital-to-analogue of the switching current module with Background calibration disclosed in digital analog converter and Figure 10
The difference of converter is：
Switching current array in this digital analog converter includes the switch electricity shown at least one Fig. 5
Stream device.
The switching current mould with front desk correction function that Figure 13 is provided for another embodiment of the present invention
The structural representation of the current mode digital-to-analog converter of block, reference picture 13, its with disclosed in Figure 11
The difference of digital analog converter is that the switching current module in sharing module group is band foreground
The switching current module of correction；
It is further to note that the digital analog converter of both types is by institute's belt switch electric current
The characteristic of device, restraint is eliminated in the switching current module with front desk correction function
Standby complementary current switch module, so as to save the area consumption that spare module brings, but
In switching current module trimming process, switching current module cannot be exported normally, current correction mistake
Journey need to be carried out on foreground.In with front desk correction digital analog converter, equally comprising switching current
At least one unit is having as described in this patent in array and decoder, and switch arrays
The switching current module of front desk correction function.This digital analog converter with front desk correction function
Maximum difference is with the digital analog converter with Background calibration function, with Background calibration work(
The digital analog converter of energy is substituted in trimming process using one group of standby complementary current switch module
The complementary current switch module for correcting is exported, such that it is able to allow digital analog converter in school
Normal work is kept in positive process, real time correction is realized.
Although being described in conjunction with the accompanying embodiments of the present invention, those skilled in the art can
To make various modifications and variations without departing from the spirit and scope of the present invention, so
Modification and within the scope of modification each falls within and is defined by the appended claims.
Claims (10)
1. a kind of switching current device, it is characterised in that including：Complementary current to be corrected is opened
Close module and correcting circuit module；
The correcting circuit module includes：The choosing of comparator, Corrective control unit and differential switch
Logical control unit；
The complementary current switch module to be corrected includes：Subnumber weighted-voltage D/A converter, the first current source,
Second current source, first switch unit and second switch unit；
The output end of the complementary current switch module to be corrected and the input of the comparator
Connection, the output end of the comparator is connected with the input of the Corrective control unit, described
The output end of Corrective control unit is selected with the subnumber weighted-voltage D/A converter and the differential switch respectively
Logical control unit connection, the differential-strobe control unit respectively with the first switch unit and
The second switch unit connection；
The subnumber weighted-voltage D/A converter is connected with first current source, and the first switch unit connects
It is connected between the output end of first current source and the complementary current switch module to be corrected,
The second switch unit is connected to second current source and the complementary current to be corrected is opened
Between the output end of pass module；
The comparator, for receive and the relatively complementary current switch module to be corrected it is defeated
Go out the current value of end output, and comparative result is sent to the Corrective control unit；
The Corrective control unit, for generating size of current control letter according to the comparative result
Number, and the size of current control signal is sent to the subnumber weighted-voltage D/A converter, so that described
Subnumber weighted-voltage D/A converter controls the defeated of first current source according to the size of current control signal
Go out；
The differential switch gating control cells, for receiving complementary current control signal, and root
The first switch unit and the second switch list are controlled according to the complementary current control signal
Unit.
2. device according to claim 1, it is characterised in that the correcting circuit module
Also include：Standby complementary current switch module, current output terminal, the 3rd switch element and the 4th
Switch element；
The standby complementary current switch module is connected with the differential switch gating control cells,
3rd switch element is connected to the current output terminal and the complementary current to be corrected is opened
Close module between, the 4th switch element be connected to the current output terminal and it is described it is standby mutually
Between benefit current switch module.
3. device according to claim 2, it is characterised in that the Corrective control unit
It is additionally operable to：
According to comparative result generation orientation output control signal, and the orientation output is controlled
Signal processed is sent to differential switch gating control cells；
Correspondingly, the differential switch gating control cells are additionally operable to：
According to the orientation output control signal, the complementary current control signal is sent to treating
Correction complementary current switch module or standby complementary current switch module.
4. device according to claim 1, it is characterised in that the correcting circuit module
Also include：5th switch element and reference current source；
5th switch element is connected to the complementary current switch module to be corrected and described
Between comparator；
The reference current source is connected between the 5th switch element and the comparator.
5. device according to claim 4, it is characterised in that the reference current source bag
Include：5th current source and the 6th current source；
It is just defeated with the comparator that 5th current source is connected to the 5th switch element
Enter between end, the 6th current source is connected to the 5th switch element and the comparator
Between negative input end.
6. device according to claim 4, it is characterised in that the Corrective control unit
It is additionally operable to：
First switch control signal and second switch control signal are generated according to comparative result；
The first switch control signal, in correcting state, connecting the 4th switch
Unit and the 5th switch element；In non-correcting state, the 4th switch element is disconnected
With the 5th switch element；
The second switch control signal, in correcting state, disconnecting the 3rd switch
Unit；In non-correcting state, the 3rd switch element is connected.
7. device according to claim 4, it is characterised in that the complementary electrical to be corrected
The output end for flowing switch module includes：First output end and the second output end；
First output end is connected with the negative input end of the comparator, second output end
Positive input terminal with the comparator is connected；
Correspondingly, the first switch unit, the second switch unit, the 3rd switch
Unit, the 4th switch element and the 5th switch element include：First switch and
Second switch；
The first switch is connected with the first output end, and the second switch and described second is exported
End connection.
8. device according to claim 7, it is characterised in that the differential switch gating
Control unit is additionally operable to：
Difference control signal is generated according to the complementary current control signal；
Positive phase signals according to the difference control signal control the of the first switch unit
The second switch of one switch and the second switch unit, and according to the difference control signal
Inversion signal controls the second switch and the second switch unit of the first switch unit
First switch.
9. a kind of digital analog converter, it is characterised in that including：The decoder of interconnection and
Switching current array；
The switching current array includes that at least one switchs as described in claim any one of 1-8
Current device；
The decoder, the digital input signals for that will receive are converted to difference control signal,
And send to the switching current array difference control signal, so that the switching current
Array corresponding with the digital input signals simulates letter according to difference control signal output
Number.
10. digital analog converter according to claim 9, it is characterised in that the switch
Current array includes：Sharing module group；
The sharing module group includes：Multiple switch current module, switching switch and a correction
Circuit module；
The switching switch connects the multiple switching current module and the correction module respectively；
The correction module, for being entered to each switching current module respectively by the switching switch
Row correction.
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| CN201510896098.8A CN106856405B (en) | 2015-12-08 | 2015-12-08 | A kind of switching current device and the digital analog converter based on the device |
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| CN106856405B (en) | 2019-10-18 |
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