CN204314766U - With the low-dropout regulator of compensating circuit - Google Patents
With the low-dropout regulator of compensating circuit Download PDFInfo
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- CN204314766U CN204314766U CN201420869535.8U CN201420869535U CN204314766U CN 204314766 U CN204314766 U CN 204314766U CN 201420869535 U CN201420869535 U CN 201420869535U CN 204314766 U CN204314766 U CN 204314766U
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Abstract
The utility model relates to a kind of low-dropout regulator with compensating circuit, comprise error amplifier and be sequentially connected in series Correctional tube, the first feedback resistance and the second feedback resistance between power supply and ground, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, also comprise building-out capacitor, between its reverse input end being connected to described error amplifier and output terminal; Compensating resistance, between its reverse input end being connected to described error amplifier and first node, described first node is the connected node formed between described first and second feedback resistances.Its stability problem using very little capacity area can solve load capacitance or load current wide variation to cause, and its response speed is faster.
Description
Technical field
The utility model relates to a kind of low-dropout regulator with compensating circuit.
Background technology
Low-dropout regulator (Low DropOut Regulators, LDO) be indispensable a kind of supply convertor in electronic circuit, utilizing passive device (as resistance) as feedback element, maintaining a kind of supply convertor of output voltage stabilization by arranging different feedback factors.
In prior art, the basic structure of LDO as shown in Figure 1, is made up of Correctional tube M0, error amplifier 100, feedback element R1 and R2, compensating circuit 200, reference voltage source 300 and various protection circuit 400 etc. usually.
Wherein, the effect of compensating circuit 200 is keeping system steady operations, and the general Muller principle that uses compensates.Have multiple implementation to compensating circuit 200 at present, but respectively have shortcoming, after such as compensating, bandwidth is too little, causes system response time slow; Or the area of required building-out capacitor is too large; Or compensating causes the Power Supply Rejection Ratio (PSR) of LDO to reduce.
Utility model content
The purpose of this utility model is, proposes a kind of structure of the low-dropout regulator with compensating circuit, its stability problem using very little capacity area can solve load capacitance or load current wide variation to cause, and its response speed is faster.
For this reason, the utility model provides a kind of low-dropout regulator with compensating circuit, comprising: error amplifier; And the Correctional tube, the first feedback resistance and the second feedback resistance that are sequentially connected in series between power supply and ground, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, it is characterized in that, also comprise: building-out capacitor, between its reverse input end being connected to described error amplifier and output terminal; Compensating resistance, between its reverse input end being connected to described error amplifier and first node, described first node is the connected node formed between described first and second feedback resistances, wherein, the resistance of described compensating resistance is m times of the resistance of described first feedback resistance, wherein 5≤m≤10, and be n times of the resistance of described second feedback resistance, wherein 5≤n≤10.
The utility model additionally provides a kind of low-dropout regulator with compensating circuit, comprising: error amplifier; And the Correctional tube, the first feedback resistance and the second feedback resistance that are sequentially connected in series between power supply and ground, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, it is characterized in that, also comprise: metal-oxide-semiconductor, its grid is connected to the output terminal of described error amplifier, is connected to the reverse input end of described error amplifier after its source electrode and drain electrode short circuit; Compensating resistance, between its reverse input end being connected to described error amplifier and first node, described first node is the connected node formed between described first and second feedback resistances, wherein, the resistance of described compensating resistance is m times of the resistance of described first feedback resistance, wherein 5≤m≤10, and be n times of the resistance of described second feedback resistance, wherein 5≤n≤10.
Further, also comprise feedback capacity, it is connected between the reverse input end of described error amplifier and described output node.
The utility model additionally provides a kind of low-dropout regulator with compensating circuit, comprising: error amplifier; And the Correctional tube, the first feedback resistance and the second feedback resistance that are sequentially connected in series between power supply and ground, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, it is characterized in that, also comprise: building-out capacitor, between its reverse input end being connected to described error amplifier and output terminal; Feedback capacity, it is connected between the reverse input end of described error amplifier and described output node.
Low-dropout regulator with compensating circuit of the present utility model, use very little capacity area just can ensure the stable of low-dropout regulator, even if the load capacitance of low-dropout regulator changes on a large scale, output current changes on a large scale, the stability of low-dropout regulator also can ensure.Further, compensation scheme of the present utility model is compared with existing compensation scheme, and its response speed is faster.
Accompanying drawing explanation
Fig. 1 is the structural representation of the low-dropout regulator with compensating circuit of prior art;
Fig. 2 is the schematic diagram of the first embodiment of the low-dropout regulator with compensating circuit of the present utility model;
Fig. 3 is the schematic diagram of the second embodiment of the low-dropout regulator with compensating circuit of the present utility model;
Fig. 4 is the schematic diagram of the 3rd embodiment of the low-dropout regulator with compensating circuit of the present utility model;
Fig. 5 is the main zeros and poles position view of the low-dropout regulator with compensating circuit of the present utility model;
Fig. 6 is the structural representation of the error amplifier of the low-dropout regulator with compensating circuit of the present utility model.
Embodiment
Below in conjunction with the drawings and specific embodiments, the low-dropout regulator with compensating circuit of the present utility model is described in further detail, but not as to restriction of the present utility model.
With reference to Fig. 2, it is the structural representation of the first embodiment of the present utility model.Low-dropout regulator with compensating circuit of the present utility model, comprise error amplifier 100, and the Correctional tube M0, the first feedback resistance R1 and the second feedback resistance R2 that are sequentially connected in series between power supply and ground, form output node N3 (this point voltage is VOUT) between the source electrode of Correctional tube M0 and the first feedback resistance R1, the grid of Correctional tube M0 is connected to the output terminal of error amplifier 100.This circuit also comprises: building-out capacitor C1, between its reverse input end being connected to error amplifier 100 and output terminal; Compensating resistance R3, it is connected between the reverse input end of error amplifier 100 and first node N1.
Wherein, the resistance of compensating resistance R3 is far longer than the resistance of the first feedback resistance R1 and the second feedback resistance R2, that is, the resistance of compensating resistance R3 is m times of the resistance of the first feedback resistance R1, and is n times of the resistance of the second feedback resistance R2.Wherein, the value of m and n sets according to applied environment (such as, the response speed etc. of the size of current of output, the situation of load capacitance, requirement), and its value is larger, and system loop is more stable, but its response speed is also slower simultaneously.Usually, m and n can value be 5 ~ 10, that is, the resistance of compensating resistance R3 is 5 ~ 10 times of R1 and R2.
Of the present utility model with in the low-dropout regulator of compensating circuit, error amplifier 100 connects into negative feedback type, to be broken principle from the short void of void, the current potential of Section Point N2 (i.e. the reverse input end of error amplifier 100) is identical with the current potential of first node N1 (connected node namely formed between the first feedback resistance R1 and the second feedback resistance R2).Therefore, adjust the ratio of the first feedback resistance R1 and the second feedback resistance R2, just can output voltage VO UT be set.After VOUT is set to desired value, the DC point of whole low-dropout regulator just determines.
Between the reverse input end that building-out capacitor C1 is connected to error amplifier 100 and output terminal, so building-out capacitor C1 equivalence is to increasing during the output terminal of error amplifier 100 A times (A is the gain of error amplifier 100, is generally more than 1000).Resistance due to compensating resistance R3 is far longer than the resistance of the first feedback resistance R1 and the second feedback resistance R2, and therefore Section Point N2 approximates the resistance of compensating resistance R3 to the resistance on ground.
So, the building-out capacitor C1 after being exaggerated and compensating resistance R3 defines the dominant pole p1 of system at Section Point N2 place.And the non-dominant pole p2 of system is at output node N3 place, its size is determined by load capacitance CL and load current.Meanwhile, building-out capacitor C1 is connected in series with compensating resistance R3 on output channel, defines the z1 at zero point of a Left half-plane, and this zero point, z1 was just in time used for improving the phase propetry of this low-dropout regulator system.So, the loop of this low-dropout regulator system primarily of two limit p1, p2 and one zero point z1 determine, as shown in Figure 5.Wherein, the frequency of each zero pole point can represent with following formula:
Wherein, A is the gain of error amplifier 100, C
1and C
lbe respectively the capacitance of building-out capacitor and load capacitance, R
3for the resistance of compensating resistance, g
m0for the mutual conductance of Correctional tube M0.
Low-dropout regulator with compensating circuit of the present utility model, only employ the compensating resistance R3 that a less building-out capacitor C1 and resistance of capacitance is larger, just determine the limit p1 of low-dropout regulator system, p2 and zero point z1 position, two limits can ensure the stable of system and have higher phase margin a zero point.
In addition, arranging of building-out capacitor C1 can also push the limit of the output terminal of error amplifier 100 to high frequency position, makes it be in beyond loop bandwidth, thus it is ignored on the impact of loop.
Preferably, the low-dropout regulator with compensating circuit of the present utility model also comprises feedback capacity C2, and it is connected between the reverse input end of error amplifier 100 and output node N3.Because the resistance with the compensating resistance R3 in the low-dropout regulator of compensating circuit of the present utility model is larger, its output voltage signal VOUT that can slow down feeds back to the speed of the input end of error amplifier 100, and this is also the reason causing low-dropout regulator response speed slow.The setting of feedback capacity C2, makes the high-frequency signal at output node N3 place feed back to the input end of error amplifier 100 rapidly, thus accelerates the response speed of low-dropout regulator.
In addition, the low-dropout regulator with compensating circuit of the present utility model, owing to employing nmos device M0 as output Correctional tube, does not increase Muller building-out capacitor, the Power Supply Rejection Ratio of system (PSR) is improved greatly on Correctional tube.
Figure 3 shows that the second embodiment of the present utility model.In this embodiment, eliminate the utilization of compensating resistance R3, but serve the effect of compensating resistance R3 with feedback resistance R1 and R2 simultaneously.Particularly, in this embodiment, the low-dropout regulator with compensating circuit of the present utility model comprises: error amplifier 100, Correctional tube M0, the first feedback resistance R1, the second feedback resistance R2, building-out capacitor C1 and feedback capacity C2.Its connected mode is identical with the first embodiment.Wherein, owing to eliminating compensating resistance R3, first node N1 overlaps with Section Point N2, and is formed as the dominant pole of this system, and namely building-out capacitor C1 and the second feedback resistance define the dominant pole of this system.Meanwhile, the output node N3 between feedback capacity C2 and the first feedback resistance R1, defines the zero point of this system.This embodiment can ensure the stability of whole system equally.
Figure 4 shows that the 3rd embodiment of the present utility model.In this embodiment, building-out capacitor C1 metal-oxide-semiconductor M1 replaces, and its grid is connected to the output terminal of error amplifier 100, is connected to the reverse input end of error amplifier 100 after its source electrode and drain electrode short circuit.More can save manufacturing cost like this.In like manner, feedback capacity C2 also can replace (not shown) with metal-oxide-semiconductor.
The implementation of the utility model medial error amplifier 100 can be as shown in Figure 6.Classical operation amplifier circuit is adopted in Fig. 6; node IN is the sampled signal of LDO output current; its voltage and output current are inversely proportional to; when output current arrives greatly certain value; the voltage of node IN can reduce; thus NMOS tube M2 is opened, the maximal value OUT that restraining error amplifier exports, plays a protective role.Be understandable that, other any high performance operational amplifier configuration can also be used in the utility model, improve the performance of LDO.
Above embodiment is only illustrative embodiments of the present utility model, can not be used for limiting the utility model, and protection domain of the present utility model is defined by the claims.Those skilled in the art can in essence of the present utility model and protection domain, and make various amendment or equivalent replacement to the utility model, these are revised or be equal to replacement and also should be considered as dropping in protection domain of the present utility model.
Claims (4)
1., with a low-dropout regulator for compensating circuit, comprising:
Error amplifier; And
Be sequentially connected in series the Correctional tube between power supply and ground, the first feedback resistance and the second feedback resistance, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, it is characterized in that, also comprises:
Building-out capacitor, between its reverse input end being connected to described error amplifier and output terminal;
Compensating resistance, between its reverse input end being connected to described error amplifier and first node, described first node is the connected node formed between described first and second feedback resistances, wherein,
The resistance of described compensating resistance is m times of the resistance of described first feedback resistance, wherein 5≤m≤10, and is n times of the resistance of described second feedback resistance, wherein 5≤n≤10.
2., with a low-dropout regulator for compensating circuit, comprising:
Error amplifier; And
Be sequentially connected in series the Correctional tube between power supply and ground, the first feedback resistance and the second feedback resistance, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, it is characterized in that, also comprises:
Metal-oxide-semiconductor, its grid is connected to the output terminal of described error amplifier, is connected to the reverse input end of described error amplifier after its source electrode and drain electrode short circuit;
Compensating resistance, between its reverse input end being connected to described error amplifier and first node, described first node is the connected node formed between described first and second feedback resistances, wherein,
The resistance of described compensating resistance is m times of the resistance of described first feedback resistance, wherein 5≤m≤10, and is n times of the resistance of described second feedback resistance, wherein 5≤n≤10.
3. the low-dropout regulator with compensating circuit according to claim 1 and 2, is characterized in that, also comprise feedback capacity, and it is connected between the reverse input end of described error amplifier and described output node.
4., with a low-dropout regulator for compensating circuit, comprising:
Error amplifier; And
Be sequentially connected in series the Correctional tube between power supply and ground, the first feedback resistance and the second feedback resistance, output node is formed between the source electrode of described Correctional tube and described first feedback resistance, the grid of described Correctional tube is connected to the output terminal of described error amplifier, it is characterized in that, also comprises:
Building-out capacitor, between its reverse input end being connected to described error amplifier and output terminal;
Feedback capacity, it is connected between the reverse input end of described error amplifier and described output node.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420869535.8U CN204314766U (en) | 2014-12-26 | 2014-12-26 | With the low-dropout regulator of compensating circuit |
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| CN201420869535.8U CN204314766U (en) | 2014-12-26 | 2014-12-26 | With the low-dropout regulator of compensating circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105786079A (en) * | 2014-12-26 | 2016-07-20 | 上海贝岭股份有限公司 | Low dropout regulator with compensating circuit |
| RU2628763C1 (en) * | 2016-05-04 | 2017-08-22 | Федеральное государственное унитарное предприятие "Научно-производственный центр автоматики и приборостроения имени академика Н.А. Пилюгина" (ФГУП "НПЦАП") | Dc voltage stabiliser |
| TWI621934B (en) * | 2015-12-07 | 2018-04-21 | 旺宏電子股份有限公司 | Semiconductor device having output compensation |
| GB2566156A (en) * | 2017-08-30 | 2019-03-06 | Apple Inc | DC-DC converter with a dynamically adapting load-line |
| US20220308609A1 (en) * | 2021-03-25 | 2022-09-29 | Qualcomm Incorporated | Power supply rejection enhancer |
-
2014
- 2014-12-26 CN CN201420869535.8U patent/CN204314766U/en active Active
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105786079A (en) * | 2014-12-26 | 2016-07-20 | 上海贝岭股份有限公司 | Low dropout regulator with compensating circuit |
| TWI621934B (en) * | 2015-12-07 | 2018-04-21 | 旺宏電子股份有限公司 | Semiconductor device having output compensation |
| RU2628763C1 (en) * | 2016-05-04 | 2017-08-22 | Федеральное государственное унитарное предприятие "Научно-производственный центр автоматики и приборостроения имени академика Н.А. Пилюгина" (ФГУП "НПЦАП") | Dc voltage stabiliser |
| GB2566156A (en) * | 2017-08-30 | 2019-03-06 | Apple Inc | DC-DC converter with a dynamically adapting load-line |
| GB2566156B (en) * | 2017-08-30 | 2019-11-27 | Apple Inc | DC-DC converter with a dynamically adapting load-line |
| US10644592B2 (en) | 2017-08-30 | 2020-05-05 | Apple Inc. | DC-DC converter with a dynamically adapting load-line |
| US20220308609A1 (en) * | 2021-03-25 | 2022-09-29 | Qualcomm Incorporated | Power supply rejection enhancer |
| US11687104B2 (en) * | 2021-03-25 | 2023-06-27 | Qualcomm Incorporated | Power supply rejection enhancer |
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