CN116225131A - Constant current drive circuit compatible with wide voltage output - Google Patents

Constant current drive circuit compatible with wide voltage output Download PDF

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Publication number
CN116225131A
CN116225131A CN202310379719.XA CN202310379719A CN116225131A CN 116225131 A CN116225131 A CN 116225131A CN 202310379719 A CN202310379719 A CN 202310379719A CN 116225131 A CN116225131 A CN 116225131A
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mos transistor
mos tube
mos
output
constant current
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CN202310379719.XA
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陈都
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Ebi Semiconductor Shenzhen Co ltd
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Ebi Semiconductor Shenzhen Co ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/561—Voltage to current converters

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)

Abstract

The invention discloses a constant current driving circuit compatible with wide voltage output, which comprises a driving input module, a driving output module and a feedback module, wherein the driving input module comprises a first MOS tube M1 and a second MOS tube M2, the feedback module comprises a first operational amplifier U1, the homodromous input end of the first operational amplifier U1 is connected with the drain electrode of a third MOS tube M3, the reverse input end of the first operational amplifier U1 is connected with the source electrode of the first MOS tube M1 and the drain electrode of the second MOS tube M2, and the output end of the first operational amplifier U1 is connected with the grid electrode of the first MOS tube M1.

Description

Constant current drive circuit compatible with wide voltage output
Technical Field
The invention relates to the technical field of constant current driving, in particular to a constant current driving circuit compatible with wide voltage output.
Background
The constant current drive circuit is widely applied to an analog circuit, and the constant current drive circuit has two main functions, one is used as a load, and the gain of the amplifier is improved due to the large alternating current output resistance of the constant current drive circuit; another is to provide a bias current and mirror up. As shown in fig. 1, a bias current ib is provided on the left, and the output Iout is a mirror image of the bias current ib, and in general, iout is N times of ib, because the eighth MOS transistor M8 is N times of the amplification factor of the seventh MOS transistor M7. To further increase the output impedance, an operational amplifier U3 is introduced in fig. 1.
However, the problem of degradation of constant current performance caused by the decrease of output voltage is still not solved, and particularly, when the voltage of an output terminal is relatively low, the performance is rapidly degraded, so that the constant current power supply is difficult to be suitable for high-performance occasions.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses a constant current drive circuit compatible with wide voltage output, and the technical scheme can ensure that the performance of the constant current drive circuit cannot be degraded when the voltage of an output end is lower, so that the range of the working voltage of the output end is expanded, and the constant current drive circuit can be applied to high-performance occasions.
The technical scheme of the invention is as follows:
a constant current driving circuit compatible with wide voltage output comprises a driving input module, a driving output module and a feedback module.
In a further technical scheme, the driving input module comprises a first MOS transistor M1 and a second MOS transistor M2, a source electrode of the first MOS transistor M1 is connected with a drain electrode of the second MOS transistor M2, a source electrode of the second MOS transistor M2 is grounded, and a drain electrode of the first MOS transistor M1 and a gate electrode of the second MOS transistor M2 are connected with a bias current end.
The driving output module comprises a third MOS tube M3, wherein the grid electrode of the third MOS tube M3 is connected with the grid electrode of the second MOS tube M2, and the source electrode of the third MOS tube M3 is grounded.
The feedback module comprises a first operational amplifier U1, wherein the homodromous input end of the first operational amplifier U1 is connected with the drain electrode of the third MOS tube M3, the reverse input end of the first operational amplifier U1 is connected with the source electrode of the first MOS tube M1 and the drain electrode of the second MOS tube M2, and the output end of the first operational amplifier U1 is connected with the grid electrode of the first MOS tube M1.
In an alternative technical scheme, the driving output module further comprises a fourth MOS transistor M4, a source electrode of the fourth MOS transistor M4 is connected with a drain electrode of the third MOS transistor M3, a gate electrode of the fourth MOS transistor M4 is connected with a bias voltage end, and a drain electrode of the fourth MOS transistor M4 is a driving output end.
In an alternative solution, the driving output module further includes a second operational amplifier U2.
Specifically, the same-direction input end of the second operational amplifier U2 is connected to the bias voltage end, the reverse input end is connected to the common end of the third MOS transistor M3 and the fourth MOS transistor M4, and the output end of the second operational amplifier U2 is connected to the gate of the fourth MOS transistor M4.
In an alternative technical scheme, the driving output module further includes a fifth MOS transistor M5.
Specifically, the drain electrode of the fifth MOS transistor M5 is connected to the gate electrode of the fourth MOS transistor M4 and is commonly connected to the bias current terminal, the source electrode of the fifth MOS transistor M5 is grounded, and the gate electrode of the fifth MOS transistor M5 is connected to the common terminal of the third MOS transistor M3 and the fourth MOS transistor M4.
Further, the first MOS transistor M1, the second MOS transistor M2, the third MOS transistor M3, the fourth MOS transistor M4 and the fifth MOS transistor M5 are NMOS transistors, or the first MOS transistor M1, the second MOS transistor M2, the third MOS transistor M3, the fourth MOS transistor M4 and the fifth MOS transistor M5 are PMOS transistors.
According to the constant-current driving circuit compatible with wide voltage output, on one hand, the technical scheme can ensure that the performance of the constant-current driving circuit cannot be degraded when the voltage of the output end is relatively low, so that the range of the working voltage of the output end is expanded. On the other hand, under the same driving current, the area of the driving tube can be effectively reduced, and the purpose of reducing the cost of the chip is achieved.
Drawings
Fig. 1 is a schematic diagram of a constant current driving circuit in the prior art.
Fig. 2 is a schematic diagram of a simulation waveform of the constant current drive circuit shown in fig. 1.
FIG. 3 is a schematic diagram of an embodiment of a constant current drive circuit compatible with wide voltage output.
FIG. 4 shows a schematic diagram of an embodiment of a constant current drive circuit compatible with wide voltage output.
Fig. 5 shows an embodiment of a constant current driving circuit compatible with a wide voltage output.
FIG. 6 shows a schematic diagram of an embodiment of a constant current drive circuit compatible with wide voltage output.
Fig. 7 is a schematic diagram of a simulation waveform of the constant current driving circuit shown in fig. 3 according to the present invention.
Fig. 8 is a schematic diagram of a simulation waveform of the constant current driving circuit shown in fig. 6 according to the present invention.
Description of the embodiments
The invention is described in further detail below with reference to the accompanying drawings.
For the purpose of better illustrating the embodiments, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the actual product dimensions; some well known structures in the drawings and omission of the description thereof will be understood by those skilled in the art. The same or similar reference numerals correspond to the same or similar components.
The constant current driving circuit provides constant current (constant current), and the working width of the output voltage is one of important indexes for measuring the advantages and disadvantages of the constant current driving circuit. The working width of the output voltage is too narrow to maintain stable constant current output, for example, the constant current value (driving current or output current) is changed when the working width of the output voltage is suddenly changed or oscillated, so that the requirement of a circuit system cannot be met. Constant current drive circuits with an excessively narrow operating width of the output voltage are difficult to be applied to high-performance occasions.
On the other hand, increasing the output impedance of the constant current drive circuit is advantageous in improving the gain of the amplifier, as the operational amplifier U3 is introduced in fig. 1, further improving the output impedance. But the working width of its output voltage is too narrow. Fig. 2 is a schematic diagram of a simulation waveform of the constant current driving circuit shown in fig. 1.
As can be seen from fig. 2 in combination with fig. 1, as the output voltage Vout decreases, M9 first exits the saturation region, and the voltage at point D increases due to the amplifying action of the operational amplifier U3. When the voltage at point D rises too high, beyond the output range of op amp U3, the voltages at points a and B will no longer match. The voltage at point a is unchanged, the voltage at point B decreases with the decrease of the output voltage Vout, so that the drain voltages of M7 and M8 are not identical, so the output terminal will not maintain a constant current.
Specifically, as can be seen from fig. 2, when the output voltage Vout is greater than 0.7V, the constant current characteristic of the output current Iout is good. But as the output voltage Vout decreases (less than 0.7V), the breaking constant current of the output current Iout follows decreasing. The critical output voltage Vout for breaking the constant current is about 0.7V.
In order to further reduce the output voltage Vout while maintaining the constant current characteristic of the output terminal, it is necessary to develop a new constant current drive circuit.
In view of the defects in the prior art, the invention discloses a constant current driving circuit compatible with wide voltage output, and the technical scheme can expand the working range of the voltage of an output end, namely the output current Iout can well maintain the output constant current characteristic under the condition of relatively wide voltage variation, and particularly maintain the constant current characteristic under the condition of low voltage output. Because of the improvement of the circuit, the area of the driving tube can be effectively reduced under the condition of achieving the same output current Iout, thereby saving the layout area of the integrated circuit and achieving the purpose of saving the cost for enterprises.
Specific embodiments of the invention are as follows:
example 1
In this embodiment, as shown in fig. 3, a constant current driving circuit compatible with wide voltage output includes a driving input module 1, a driving output module 3 and a feedback module 2.
In a specific technical scheme of this embodiment, the driving input module 1 includes a first MOS transistor M1 and a second MOS transistor M2, a source electrode of the first MOS transistor M1 is connected to a drain electrode of the second MOS transistor M2, a source electrode of the second MOS transistor M2 is grounded, and a drain electrode of the first MOS transistor M1 is connected to a gate electrode of the second MOS transistor M2 to form a bias current end.
The driving output module 3 comprises a third MOS tube M3, wherein a grid electrode of the third MOS tube M3 is connected with a grid electrode of the second MOS tube M2, and a source electrode of the third MOS tube M3 is grounded.
In this embodiment, the drain electrode of the third MOS transistor M3 is a driving output end, and the driving output end is a driving current output end, that is, the output current Iout.
In this embodiment, the feedback module 2 includes a first operational amplifier U1, the co-directional input end of the first operational amplifier U1 is connected to the drain electrode of the third MOS transistor M3, the reverse input end of the first operational amplifier U1 is connected to the source electrode of the first MOS transistor M1 and the drain electrode of the second MOS transistor M2, and the output end of the first operational amplifier U1 is connected to the gate electrode of the first MOS transistor M1.
In this embodiment, the third MOS transistor M3 is N times the second MOS transistor M2, and the output current Iout is N times the bias current ib.
In this embodiment, a feedback structure is adopted, in this feedback structure, the gain of the first operational amplifier U1 is a (typically, the gain of the operational amplifier is greater than 1000 times), and then the output impedance is r×a, where R is the original output impedance of the constant current driving circuit, so this embodiment greatly improves the output impedance and improves the constant current characteristic.
In this embodiment, as shown in fig. 3, unlike the connection of the operational amplifier U3 in the constant current driving circuit shown in fig. 1, the first operational amplifier U1 in this embodiment feeds back the output voltage Vout to the bias terminal (the gate terminal of the first MOS transistor M1), and at this time, the voltage at point a follows the change of the voltage at point B, and the voltages at points D and C are automatically adjusted according to the voltage at point B. Because a first MOS transistor M1 of a cathode tube is added in this embodiment, the output of the first operational amplifier U1 is connected to the gate of the first MOS transistor M1. The gate voltages of the second MOS transistor M2 and the third MOS transistor M3 (i.e., the drain voltage of the first MOS transistor M1) are indirectly adjusted by controlling the gate voltage of the first MOS transistor M1.
The specific technical effect of this embodiment is as shown in the simulation waveform diagram shown in fig. 7.
As shown in fig. 7, when the output voltage Vout is higher, the first MOS transistor M1 operates in the linear region, the voltage at the point a does not change with the output voltage B, and the voltage at the point a starts to change with the voltage at the point B as the output voltage decreases. The output current Iout can maintain constant current characteristics when the output voltage Vout is low.
Specifically, as can be seen from fig. 7, when the output voltage Vout is reduced to 0.06V, the output current Iout can still be well maintained at the constant current output of 10mA, so that compared with the prior art, the working width of the output terminal voltage Vout is greatly expanded in this embodiment.
Example 2
In this embodiment, on the basis of embodiment 1, the fourth MOS transistor M4 is added to the driving output module 3, as shown in fig. 4.
In this embodiment, a source of the fourth MOS transistor M4 is connected to a drain of the third MOS transistor M3, a gate of the fourth MOS transistor M4 is connected to a bias voltage terminal, and a drain of the fourth MOS transistor M4 is a driving output terminal.
The present embodiment can expand the operation width of the output terminal voltage Vout.
Example 3
In this embodiment, on the basis of embodiment 2, the driving output module 3 adds a second operational amplifier U2, as shown in fig. 5.
Specifically, the same-direction input end of the second operational amplifier U2 is connected to the bias voltage end, the reverse input end is connected to the common end of the third MOS transistor M3 and the fourth MOS transistor M4, and the output end of the second operational amplifier U2 is connected to the gate of the fourth MOS transistor M4.
The present embodiment can expand the operation width of the output terminal voltage Vout.
Example 4
In this embodiment, on the basis of embodiment 2, the fifth MOS transistor M5 is added to the driving output module 3, as shown in fig. 6.
Specifically, the drain electrode of the fifth MOS transistor M5 is connected to the gate electrode of the fourth MOS transistor M4 and is commonly connected to the bias current terminal, the source electrode of the fifth MOS transistor M5 is grounded, and the gate electrode of the fifth MOS transistor M5 is connected to the common terminal of the third MOS transistor M3 and the fourth MOS transistor M4.
The present embodiment can expand the operation width of the output terminal voltage Vout.
The specific technical effect of this embodiment is as shown in the simulation waveform diagram shown in fig. 8.
Specifically, as can be seen from fig. 7, due to the addition of the fifth MOS transistor M5, the voltage at the point B is isolated from the output terminal, so that the voltage at the point B remains constant when the output voltage Vout increases. Thus, the point A can better follow the voltage of the point B, and the output current is more constant.
As shown in fig. 7, when the output voltage Vout is reduced to 0.1V, the output current Iout can still be well maintained at the constant current output of 10mA, so that compared with the prior art, the working width of the output terminal voltage Vout is greatly expanded in this embodiment.
In embodiments 1, 2, 3 and 4 of the present invention, the first MOS transistor M1, the second MOS transistor M2, the third MOS transistor M3, the fourth MOS transistor M4 and the fifth MOS transistor M5 are all illustrated by NMOS transistors.
Because of the dual property of the NMOS tube and the PMOS tube, the first MOS tube M1, the second MOS tube M2, the third MOS tube M3, the fourth MOS tube M4 and the fifth MOS tube M5 can be replaced by PMOS tubes.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims (5)

1. A constant current drive circuit compatible with wide voltage output, characterized by comprising:
the driving input module comprises a first MOS tube M1 and a second MOS tube M2, wherein a source electrode of the first MOS tube M1 is connected with a drain electrode of the second MOS tube M2, a source electrode of the second MOS tube M2 is grounded, and a drain electrode of the first MOS tube M1 and a grid electrode of the second MOS tube M2 are connected with a bias current end;
the driving output module comprises a third MOS tube M3, the grid electrode of the third MOS tube M3 is connected with the grid electrode of the second MOS tube M2, and the source electrode of the third MOS tube M3 is grounded;
the feedback module comprises a first operational amplifier U1, wherein the homodromous input end of the first operational amplifier U1 is connected with the drain electrode of the third MOS tube M3, the reverse input end of the first operational amplifier U1 is connected with the source electrode of the first MOS tube M1 and the drain electrode of the second MOS tube M2, and the output end of the first operational amplifier U1 is connected with the grid electrode of the first MOS tube M1.
2. The constant current driving circuit compatible with wide voltage output according to claim 1, wherein the driving output module further comprises a fourth MOS transistor M4, a source electrode of the fourth MOS transistor M4 is connected to a drain electrode of the third MOS transistor M3, a gate electrode of the fourth MOS transistor M4 is connected to a bias voltage terminal, and a drain electrode of the fourth MOS transistor M4 is a driving output terminal.
3. The constant current driving circuit compatible with wide voltage output according to claim 2, wherein the driving output module further comprises a second operational amplifier U2;
the same-direction input end of the second operational amplifier U2 is connected with a bias voltage end, the reverse input end of the second operational amplifier U2 is connected with the common end of the third MOS tube M3 and the fourth MOS tube M4, and the output end of the second operational amplifier U2 is connected with the grid electrode of the fourth MOS tube M4.
4. The constant current driving circuit compatible with wide voltage output according to claim 2, wherein the driving output module further comprises a fifth MOS transistor M5;
the drain electrode of the fifth MOS tube M5 is connected with the grid electrode of the fourth MOS tube M4 and is jointly connected with the bias current end, the source electrode of the fifth MOS tube M5 is grounded, and the grid electrode of the fifth MOS tube M5 is connected with the common end of the third MOS tube M3 and the fourth MOS tube M4.
5. The constant current driving circuit compatible with wide voltage output according to claim 1, wherein the first MOS transistor M1, the second MOS transistor M2, the third MOS transistor M3, the fourth MOS transistor M4 and the fifth MOS transistor M5 are NMOS transistors, or the first MOS transistor M1, the second MOS transistor M2, the third MOS transistor M3, the fourth MOS transistor M4 and the fifth MOS transistor M5 are PMOS transistors.
CN202310379719.XA 2023-04-11 2023-04-11 Constant current drive circuit compatible with wide voltage output Pending CN116225131A (en)

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Application Number Priority Date Filing Date Title
CN202310379719.XA CN116225131A (en) 2023-04-11 2023-04-11 Constant current drive circuit compatible with wide voltage output

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310379719.XA CN116225131A (en) 2023-04-11 2023-04-11 Constant current drive circuit compatible with wide voltage output

Publications (1)

Publication Number Publication Date
CN116225131A true CN116225131A (en) 2023-06-06

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CN202310379719.XA Pending CN116225131A (en) 2023-04-11 2023-04-11 Constant current drive circuit compatible with wide voltage output

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