CN101661301B - Low-voltage-drop linear voltage regulator with frequency compensation - Google Patents
Low-voltage-drop linear voltage regulator with frequency compensation Download PDFInfo
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- CN101661301B CN101661301B CN2008102126193A CN200810212619A CN101661301B CN 101661301 B CN101661301 B CN 101661301B CN 2008102126193 A CN2008102126193 A CN 2008102126193A CN 200810212619 A CN200810212619 A CN 200810212619A CN 101661301 B CN101661301 B CN 101661301B
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Abstract
The invention provides a low-voltage-drop linear voltage regulator with efficiency and frequency compensation, comprising an error amplifier, a transmission element, a voltage division circuit and a pole control unit. The error amplifier is used for generating a control signal according to a reference voltage and a feedback voltage; the transmission element is coupled to the error amplifier and is used for regulating an input voltage according to the control signal so as to generate an output voltage; the voltage division circuit is coupled to the transmission element and is used for dividingthe output voltage so as to generate the feedback voltage; and the pole control unit is coupled to the transmission element, is used for supplying output capacitance and regulating the output capacitance according to the output impedance variation of the transmission element so as to fix the generation frequency of a pole and further maintain the stability of a loop.
Description
Technical field
The present invention is meant a kind of frequency compensated low-voltage-drop linear voltage regulator of effect that has, and refers to a kind of according to load current variation adjustment output capacitance size, to fix the low-voltage-drop linear voltage regulator that a limit produces frequency especially.
Background technology
Linear voltage regulator has the ability that regulated output voltage is provided, low-voltage-drop linear voltage regulator (Low Drop-Out Voltage Regulator wherein, LDO Regulator) more because output voltage can be in the extreme near input voltage, and the power consumption of saving power transistor, make battery life can keep for a long time, therefore be widely used on the various portable type electronic products, for example walkman, digital camera, mobile phone, notebook or the like.
Please refer to Fig. 1, Fig. 1 is the synoptic diagram of a known low dropout voltage regulator 10.Low dropout voltage regulator 10 includes an error amplifier 110, a transfer element 120, a bleeder circuit 130 and an output capacitance Cout, its principle of work mainly is to produce a feedback voltage V FB by bleeder circuit 130, so that error amplifier 110 is according to the difference control transmission element 120 of feedback voltage V FB and reference voltage VREF, and then produce stable output voltage.Wherein, output capacitance Cout is used in load current I
LoadDuring flip-flop, temporarily provide load required a large amount of electric currents, to improve the transient response of output voltage.
In general, loop degree of stability (Stability) is important subject under discussion in the process of design low-voltage-drop linear voltage regulator always.In traditional circuit framework, load current size and output capacitance value are two factors that mainly influence degree of stability.By setting up the small signal circuit model of above-mentioned low dropout voltage regulator, can find in the whole loop main two limits that exist, the design of itself and degree of stability has confidential relation.First limit, dominant pole just is that the output impedance by stray capacitance and error amplifier between error amplifier and transfer element is formed, it can be represented by following formula:
Wherein Roe and Cpar represent the output impedance of error amplifier and the size of stray capacitance respectively.Second limit then is that the output impedance by output capacitance and low-voltage-drop linear voltage regulator is caused, and it can be represented by following formula:
Wherein Ro and λ represent the output impedance and the passage length index of modulation of transfer element 120 respectively.
As from the foregoing, the frequency of second limit can be along with load current I
LoadChange and change, and the position of other limits can't be along with variation.Yet, because pole frequency drift meeting changes the frequency response of low dropout voltage regulator significantly, therefore in some cases the unsettled situation in loop may take place because of phase margin (Phase Margin) is not enough.
In sum, known low-voltage-drop linear voltage regulator can change the problem that produces loop stability because of load current.
Summary of the invention
Therefore, purpose of the present invention promptly is to provide a kind of low-voltage-drop linear voltage regulator with efficiency and frequency compensation.
The present invention discloses a kind of low-voltage-drop linear voltage regulator with efficiency and frequency compensation, and it includes an error amplifier, a transfer element, a bleeder circuit and a limit control module.This error amplifier is used for producing a control signal according to a reference voltage and a feedback voltage.This transfer element is coupled to this error amplifier, is used for according to this control signal one input voltage being adjusted, to produce an output voltage.This bleeder circuit is coupled to this transfer element, is used for this output voltage is carried out dividing potential drop, to produce this feedback voltage.This limit control module is coupled to this transfer element, is used to provide an output capacitance, and changes according to the output impedance of this transfer element, adjusts the size of this output capacitance, fixing the generation frequency of a limit, and then keeps the stability in loop.
Description of drawings
Fig. 1 is the synoptic diagram of a known low dropout voltage regulator.
Fig. 2 has the synoptic diagram of a low-voltage-drop linear voltage regulator of efficiency and frequency compensation for the present invention.
Fig. 3 is the embodiment synoptic diagram of the present invention's one limit control module.
Drawing reference numeral
10,20 low dropout voltage regulators
110,210 error amplifiers
120,220 transfer elements
130,230 bleeder circuits
The Cout output capacitance
The VFB feedback voltage
The VREF reference voltage
I
LoadLoad current
240,30 limit control modules
The CTRL control signal
The Vin input voltage
The Vout output voltage
MP1 P type metal-oxide half field effect transistor
R1, R2 divider resistance
C1 first electric capacity
C2 second electric capacity
The SW1 change-over switch
Embodiment
Please refer to Fig. 2, Fig. 2 has the synoptic diagram of a low-voltage-drop linear voltage regulator 20 of efficiency and frequency compensation for the present invention.Low-voltage-drop linear voltage regulator 20 includes an error amplifier 210, a transfer element 220, a bleeder circuit 230 and a limit control module 240.Error amplifier 210 is used for producing a control signal CTRL according to a reference voltage VREF and a feedback voltage V FB.Transfer element 220 is coupled to error amplifier 210, is used for according to control signal CTRL one input voltage vin being adjusted, to produce an output voltage V out.Bleeder circuit 230 is coupled to transfer element 220, is used for output voltage V out is carried out dividing potential drop, to produce feedback voltage V FB.Limit control module 240 is coupled to transfer element 220, is used to provide an output capacitance Cout, and changes according to the output impedance of transfer element 220, adjusts the size of output capacitance Cout, fixing the generation frequency of a limit, and then keeps the stability in loop.Preferably, transfer element 220 can be realized by a P-type mos field effect transistor M P1, and bleeder circuit 230 can be realized by divider resistance R1, R2, as shown in Figure 2.
As stated in the Background Art, one pole frequency of low-voltage-drop linear voltage regulator is by output impedance and both big or small product decisions of output capacitance of transfer element, and when output impedance changes, when for example the mode of operation of back level load changed, known low-voltage-drop linear voltage regulator can produce the problem of loop stability because of the pole frequency drift.Therefore, low-voltage-drop linear voltage regulator 20 of the present invention can pass through limit control module 240, changes according to the output impedance of transfer element 220, adjusts the size of output capacitance Cout, with the fixing generation frequency of limit, and then keeps the stability in loop.
For instance, when back level load switched to running (Active) state by dormant state, it (was load current I that back level load meeting is drawn a large amount of electric currents from transfer element 220
Load), make the output impedance of transfer element 220 diminish, in this case, if can increase the size of output capacitance Cout accordingly, the fixing generation frequency of limit then, and keep the stability in loop.Please refer to Fig. 3, Fig. 3 is the embodiment synoptic diagram of the present invention's one limit control module 30.Limit control module 30 is used for realizing the limit control module 240 of Fig. 2, and it includes one first capacitor C 1, one second capacitor C 2 and is switched switch SW 1.First capacitor C 1 and second capacitor C 2 are used to provide the capacitance of two fixed sizes respectively.Change-over switch SW1 is coupled to second capacitor C 2, then is used for mode of operation according to the load of back level, second electric capacity is switched be coupled to transfer element 220, to adjust the size of output capacitance Cout.
Preferably, when load elements is in a running during (Active) state, change-over switch SW1 forms short circuit, so that second capacitor C 2 is coupled to transfer element 220, thus the size of increase output capacitance Cout.In this case, the big young pathbreaker of output capacitance Cout equals first capacitor C 1 and second capacitor C, 2 sums.On the contrary, when load elements was in a dormancy (Sleep) state, change-over switch SW1 then formed and opens circuit, and the size of output capacitance Cout only equals the size of first capacitor C 1 at this moment.
Thus, be in dormant state compared to back level load, when level load in back is in operating state and when the output impedance of transfer element 220 is diminished, the present invention is coupled to transfer element 220 by change-over switch SW1 with second capacitor C 2, with the size of increase output capacitance Cout, and make low-voltage-drop linear voltage regulator 20 produce fixing pole frequency.In this case, no matter back level load is in operating state or dormant state, low-voltage-drop linear voltage regulator of the present invention all has identical frequency response, and therefore can improve known technology produces the loop problem of unstable because of the pole frequency drift.
In addition, by suitably selecting the size of first capacitor C 1 and second capacitor C 2, the present invention is except the stability that can keep the loop, but the more transient response of optimization output voltage, and it is known to those skilled in the art, does not give unnecessary details in this.
In brief, the present invention is by dynamically switching the mode of output capacitance, and the drift of antipodal points frequency compensates, and therefore need realize frequency compensation by complicated circuit compared to known technology, and frequency compensation mode of the present invention only need realize by simple circuit.It should be noted that the foregoing description only is of the present invention one explanation for example, those skilled in the art revise when making according to the actual requirements suitably, all belong to scope of the present invention as long as have identical output capacitance adjustment function.
In sum, the present invention is used to provide a kind of low-voltage-drop linear voltage regulator with efficiency and frequency compensation, and it is according to the variation of output impedance, adjusts the size of output capacitance, with the fixing generation frequency of limit, and then keeps the stability in loop.Preferably, the present invention can be applicable to realize in built-in mode the low-voltage-drop linear voltage regulator of output capacitance.
The above only is preferred embodiment of the present invention, and all equalizations of doing according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.
Claims (8)
1. one kind has frequency compensated low-voltage-drop linear voltage regulator, it is characterized in that, this low-voltage-drop linear voltage regulator includes:
One error amplifier is used for producing a control signal according to a reference voltage and a feedback voltage;
One transistor is coupled to this error amplifier, is used for according to this control signal one input voltage being adjusted, to produce an output voltage;
One bleeder circuit is coupled to this transistor, is used for this output voltage is carried out dividing potential drop, to produce this feedback voltage; And
One limit control module is coupled to this transistor, is used to provide an output capacitance, and changes according to this transistorized output impedance, adjusts the size of this output capacitance, fixing the generation frequency of a limit, and then keeps the stability in loop.
2. low-voltage-drop linear voltage regulator as claimed in claim 1 is characterized in that, the generation frequency of this limit is by the big or small product decision of this transistorized output impedance and this output capacitance.
3. low-voltage-drop linear voltage regulator as claimed in claim 1 is characterized in that, this transistorized output impedance changes according to the mode of operation of a load elements.
4. low-voltage-drop linear voltage regulator as claimed in claim 3 is characterized in that, this limit control module includes:
One first electric capacity;
One second electric capacity; And
One switches switch, is coupled to this second electric capacity, is used for mode of operation according to this load elements, this second electric capacity is switched be coupled to this transistor, to adjust the size of this output capacitance.
5. low-voltage-drop linear voltage regulator as claimed in claim 4, it is characterized in that, this change-over switch forms short circuit when this load elements is in an operating state, so that this second electric capacity is coupled to this transistor, and the size of this output capacitance equals a big or small summation of this first electric capacity and this second electric capacity.
6. low-voltage-drop linear voltage regulator as claimed in claim 5 is characterized in that, this change-over switch forms when this load elements is in a dormant state and opens circuit, and the size of this output capacitance equals the size of this first electric capacity.
7. low-voltage-drop linear voltage regulator as claimed in claim 1 is characterized in that, this transistor is a P type metal oxide semiconductor field effect transistor.
8. low-voltage-drop linear voltage regulator as claimed in claim 1 is characterized in that this bleeder circuit includes a plurality of divider resistances.
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| CN2008102126193A CN101661301B (en) | 2008-08-25 | 2008-08-25 | Low-voltage-drop linear voltage regulator with frequency compensation |
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| CN2008102126193A CN101661301B (en) | 2008-08-25 | 2008-08-25 | Low-voltage-drop linear voltage regulator with frequency compensation |
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| CN101661301B true CN101661301B (en) | 2011-06-29 |
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Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8265574B2 (en) * | 2010-04-09 | 2012-09-11 | Triquint Semiconductor, Inc. | Voltage regulator with control loop for avoiding hard saturation |
| JP2014026610A (en) * | 2012-07-30 | 2014-02-06 | Seiko Instruments Inc | Regulator |
| CN104750160B (en) * | 2013-12-30 | 2017-05-24 | 国民技术股份有限公司 | Output power control circuit of power amplifier |
| CN105138062B (en) * | 2014-05-29 | 2017-08-04 | 展讯通信（上海）有限公司 | Improve the system of low pressure difference linear voltage regulator load regulation |
| US9882472B2 (en) * | 2014-09-25 | 2018-01-30 | Intel Corporation | Techniques for power supply topologies with capacitance management to reduce power loss associated with charging and discharging when cycling between power states |
| US9684325B1 (en) * | 2016-01-28 | 2017-06-20 | Qualcomm Incorporated | Low dropout voltage regulator with improved power supply rejection |
| CN106788356B (en) * | 2016-12-13 | 2019-04-26 | 电子科技大学 | A kind of linear voltage regulator with real-time frequency compensation function |
| CN110221644B (en) * | 2019-05-23 | 2021-02-26 | 上海艾为电子技术股份有限公司 | Chip and external RSET resistance open circuit monitoring circuit thereof |
| CN111273720B (en) * | 2020-03-04 | 2022-02-22 | 中国电子科技集团公司第二十四研究所 | Compensation zero generation circuit for linear voltage regulator |
| CN111596716A (en) * | 2020-05-29 | 2020-08-28 | 北京集创北方科技股份有限公司 | Voltage adjusting device, chip, power supply and electronic equipment |
| CN112327987B (en) * | 2020-11-18 | 2022-03-29 | 上海艾为电子技术股份有限公司 | Low dropout regulator and electronic equipment |
| CN113110670B (en) * | 2021-04-15 | 2022-07-08 | 杭州加速科技有限公司 | Control system and control method for improving stability of power supply output voltage |
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| WO2006116520A1 (en) * | 2005-04-26 | 2006-11-02 | Texas Instruments Incorporated | Apparatus and method to compensate for effects of load capacitance on power regulator |
| CN101140478A (en) * | 2007-09-04 | 2008-03-12 | 北京时代民芯科技有限公司 | Low pressure difference linearity voltage stabilizer for enhancing performance by amplifier embedded compensation network |
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| WO2006116520A1 (en) * | 2005-04-26 | 2006-11-02 | Texas Instruments Incorporated | Apparatus and method to compensate for effects of load capacitance on power regulator |
| CN101167031A (en) * | 2005-04-26 | 2008-04-23 | 德克萨斯仪器股份有限公司 | Apparatus and method to compensate for effects of load capacitance on power regulator |
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