CN204833032U - Electric capacity LDO circuit in transient response reinforcing matrix - Google Patents
Electric capacity LDO circuit in transient response reinforcing matrix Download PDFInfo
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- CN204833032U CN204833032U CN201520041773.4U CN201520041773U CN204833032U CN 204833032 U CN204833032 U CN 204833032U CN 201520041773 U CN201520041773 U CN 201520041773U CN 204833032 U CN204833032 U CN 204833032U
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- ldo
- transient response
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Abstract
The utility model discloses an electric capacity LDO circuit in transient response reinforcing matrix. Produce circuit, error amplifier (AMP), power tube, resistor string partial pressure unit and route, the route that discharges, coupling capacitance cc1 and the cc2 of charging including benchmark (VREF). When load current suddenlys change, utilize charge route or the route that discharges of design to go on dashing fast discharging to the gate capacitance (Cg) of power tube. The utility model discloses a novel, effectual quick transient response compensates the route, when realizing the transient response compensation, has realized frequency compensation well, can guarantee the piece on LDO remain stable in whole load current excursion. The utility model discloses a power tube of LDO circuit can be worked at the linear zone, and its input/output pressure differential can be controlled within the 0.1V. Do not need external output capacitance, application circuit is simple, and is with low costs.
Description
Technical field
The utility model relates to a kind of integrated circuit, and particularly on sheet, a kind of transient response of the low pressure difference linear voltage regulator (CAP_lessLDO) of capacitance structure strengthens technology.Background technology
Owing to having the features such as circuit is simple, noise is little, pressure reduction is little, low in energy consumption, in battery powered radio frequency SOC, low pressure difference linear voltage regulator (LowDrop-outvoltageRegulator is called for short LDO) is widely used.
Due to the restriction of integrated circuit technology, the large output capacitance of the uF magnitude that traditional LDO needs can only be realized by external capacitor.And battery powered radio frequency SOC may need multi-group power voltage, provide separately independently power supply to respectively radio frequency reception part, transmitting portion, digital circuits section, so a SOC may need multi-group power pin, multiple external bulky capacitor.Each of which increases system cost, increase application complexity.For reducing costs, on sheet, electric capacity (CAP_less) LDO manages to remove the outer bulky capacitor of sheet, and the 100pF magnitude electric capacity only utilizing chip internal integrated, realizes frequency compensation.
When the output capacitance of LDO is lowered several order of magnitude, its transient response ability will be greatly affected.When the snap time that load current is undergone mutation is less than the unity gain bandwidth of LDO reciprocal, the feedback control loop of traditional LDO has little time reaction, can only utilize external bulky capacitor to load provide moment charging and discharging capabilities, regulated output voltage.Illustrate: have such LDO system, have the bandwidth of 1MHz, power tube parasitic gate electric capacity Cg=20pF, grid voltage changes delta V=1V, LDO are to the charging and discharging currents I of grid capacitance
sr=20uA, external capacitor gets Co=4.7uF, parasitic equivalent series resistance R
eSR=0; The amplitude I of load current Spline smoothing in 1us
load-max=50mA, then can pass through following formulae discovery LDO output end voltage maximum changing value
be approximately 20mV, be easy to meet index request (wherein
reaction time for grid capacitance voltage).
Because output capacitance has been lowered several order of magnitude, on sheet, the transient response characteristic of electric capacity LDO will be greatly affected.Same system, when Co is reduced to 1nF, same formulae discovery obtains the maximum change of LDO output end voltage and reaches 100V, so do not take LDO on the sheet of any transient response indemnifying measure will cannot reach the index request of quick responsive load curent change at all.
Summary of the invention
For the problems referred to above, the utility model discloses a kind of transient response to be strengthened matrix and powers on and hold LDO circuit.The purpose of this utility model is, removes the bulky capacitor that chip is external, changes inner integrated 100pF small capacitances into, realize Voltage Cortrol, frequency compensation, have good transient response ability simultaneously.The utility model is achieved by the following technical solution.
Disclosed in the utility model, a kind of transient response enhancing matrix powers on and holds LDO circuit, it is characterized in that, electric capacity CINT on the sheet comprising reference voltage source, error amplifier, power tube, resistance string partial pressure unit, charging path, discharge path, coupling capacitance Cc1 and Cc2 and 100pF; The negative terminal of error amplifier connects reference voltage source, the centre tap of the resistance string partial pressure unit that the positive termination of error amplifier is made up of R1 and R2, the grid of the output termination power tube of error amplifier, the input end of the drain electrode connecting resistance string partial pressure unit of power tube; Charging path is connected with coupling capacitance Cc2, and be connected across between the grid of power tube and drain electrode, discharge path is connected with coupling capacitance Cc1, is connected across between the grid of power tube and drain electrode; Electric capacity on the sheet of the output termination 100pF of described LDO circuit.
Further, described charging path, it is characterized in that, coupling capacitance Cc2 mono-termination LDO output voltage terminal, the drain electrode of another termination NMOS tube Mc1, NMOS tube Mc1 and NMOS tube Mc2 is connected into current lens unit, PMOS Mc3 and PMOS Mc4 is connected into current lens unit, the drain electrode of NMOS tube Mc2 connects grid and the drain electrode of PMOS Mc3, and the drain electrode of PMOS Mc4 connects the grid of power tube, and current source I2 provides bias current for charging path.
Further, described discharge path, is characterized in that, coupling capacitance Cc1 mono-termination LDO output voltage terminal, the source electrode of another termination NMOS tube Mf and the grid of NMOS tube Mb, the drain electrode of NMOS tube Mb connects the grid of NMOS tube Mf, and current source Ib and I1 provides bias current for discharge path.
Advantage of the present utility model and effect are:
(1) of the present utility model upper LDO can remove the outer electric capacity of sheet, saves chip pin resource, saves PCB surface and amass.
(2) fast transient response of the present utility model compensates path, while realizing transient response compensation, achieves frequency compensation well, can ensure that on sheet, LDO keeps stable in whole load current variation range.
(3) LDO circuit of the present utility model has less power tube, saving chip area, and can be operated in linear zone, pressure reduction is little, and conversion efficiency is high, extends service time of battery.
Accompanying drawing explanation
By the figure in accompanying drawing, by way of example, and non-limited way carrys out diagram embodiment of the present utility model, and reference number identical in the drawings refers to similar element.
Fig. 1 is traditional outer bulky capacitor LDO structural representation of sheet.
Fig. 2 is that transient response of the present utility model strengthens matrix and powers on and hold the diagram of LDO circuit.
Fig. 3 be of the present utility model in Fig. 2 on sheet electric capacity LDO power tube gate discharge path diagram.
Fig. 4 be of the present utility model in Fig. 2 on sheet electric capacity LDO power tube gate charges path diagram.
Fig. 5 is the diagram of the AC small signal equivalent circuit holding LDO circuit that powers on for transient response enhancing matrix in Fig. 2 of the present utility model.
Fig. 6 is that of the present utility model powering on for transient response enhancing matrix in Fig. 2 holds the zero-pole map of LDO circuit.
Embodiment
Fig. 1 shows the outer bulky capacitor LDO structural drawing of traditional sheet.Generally include reference voltage source, error amplifier, resistance string partial pressure unit, power tube and external ceramic condenser Co.R
oUTrepresent load circuit.In addition, traditional LDO utilizes the equivalent series resistance formation zero point of the outer tantalum electric capacity of sheet or inside separately to establish special phase compensating circuit to realize the compensation of LDO loop stability.
Reference voltage generating circuit as one of the input of error amplifier, for providing reference voltage.But when load current slowly changes, electric capacity Co output end voltage changes, and resistance string partial pressure unit produces the voltage division signal of output voltage VO UT, feeds back to another input end of error amplifier.Under the control of feedback voltage, error amplifier produces corresponding output signal, Modulating Power tube current, realizes adjustment output voltage (V
oUT) object.When the snap time that load current is undergone mutation is less than the unity gain bandwidth of LDO reciprocal, the feedback control loop of traditional LDO has little time reaction, can only utilize external bulky capacitor Co to load provide moment charging and discharging capabilities, regulated output voltage.Because external capacitor Co is comparatively large, be easy to meet index request.
Fig. 2 shows transient response in the utility model to be strengthened matrix and powers on and hold the embodiment of LDO circuit.Electric capacity C on the sheet comprising reference voltage source, error amplifier, power tube, resistance string partial pressure unit and charging path, discharge path, coupling capacitance Cc1 and Cc2 and 100pF
iNT.The same with traditional LDO structure, reference voltage source provides the reference input of error amplifier, and resistance string partial pressure unit, error amplifier, power tube are connected into feedback control loop.LDO output voltage coincidence theory value under feedback control loop guarantee stable state.Because output capacitance has been lowered several order of magnitude, on sheet, the transient response characteristic of electric capacity LDO will be greatly affected.Background technology is talked about in [0004]: when Co is reduced to 100pF magnitude, does not take LDO on the sheet of any transient response indemnifying measure cannot reach the index request of quick responsive load curent change.
Fig. 3 show of the present utility model in Fig. 2 the embodiment of the power tube gate discharge path of electric capacity LDO on sheet.Discharge path is primarily of upper and lower current source I1, amplifying circuit AMP1, and feedback NMOS tube Mf and coupling capacitance Cc1 is formed.Source electrode due to NMOS tube Mf is Low ESR input node, the electric current of the reflection LDO output end voltage transient changing that electric capacity Cc1 samples can arrive the grid of power tube by NMOS tube Mf completely, and can not be formed the feedforward path of the output from power tube grid to LDO by Cc1.When load current upwards suddenlys change, sampling capacitance Cc1 samples the reduction of output voltage, thus causing the source voltage of NMOS tube to reduce, the increase of the gate source voltage VGS of NMOS tube Mf causes the change of electric current at once, forms the large electric current that sparks to power tube grid.Therefore the delay of the feedback network of sample circuit and coupled circuit combination formation is very little, can form unidirectional feedback network fast, makes the gate voltage of power tube respond rapidly the change of LDO output.In this structure, the size impact load current of the metal-oxide-semiconductor Mf that bias current I1 is connected with altogether grid upwards saltus step time transient response: bias current I1 is larger, and discharge current is larger, and transient response is faster; The size of metal-oxide-semiconductor Mf is larger, and enough little overdrive voltage just can produce very large immediate current, and transient response is faster.NMOS tube Mb and current source Ib in amplifying circuit AMP1 corresponding diagram 2.In order to increase transient current further, the utility model adopts feedback method, increases the overdrive voltage of NMOS tube Mf, increases spark electric current.When sampling capacitance Cc1 samples the decline of output voltage, amplifier makes NMOS tube Mf grid voltage raise, thus NMOS tube Mf gate source voltage VGS is increased further, thus under the condition of identical metal-oxide-semiconductor size, increase the electric current that sparks from power tube grid to LDO output terminal.Say on the other hand, negative feedback increases the equivalent transconductance of NMOS tube, reduces node V
' gequivalent input impedance, accelerate transient response.
Fig. 4 show of the present utility model in Fig. 2 the embodiment of the power tube gate charges path of electric capacity LDO on sheet.Charging path primarily of current source I2, current mirror unit Mc1, Mc2 and Mc3, Mc4, and coupling capacitance Cc2 form.When load current suddenlys change downwards, utilize sampling capacitance Cc2 respond to the rising of output voltage and be converted into electric current, this electric current doubly takes advantage of the charging current as power tube grid after amplification through current-mirror structure, realizes the object of fast transient response.Now, because NMOS tube Mf closes, discharge path is inoperative.
Transient response described in Fig. 2 strengthens matrix and powers on and hold LDO circuit and comprise a power tube.Described power tube can be operated in saturation region or linear zone.When load current is larger, allow power tube to be operated in linear zone, have two large benefits: one, pressure reduction is less, and conversion efficiency is high; Its two, the power tube being operated in linear zone can use less breadth length ratio, and its grid capacitance can be less, thus more easily improve transient response characteristic.
Fig. 5 is that of the present utility model powering on for transient response enhancing matrix in Fig. 2 holds the AC small signal equivalent circuit of LDO circuit.Suppose that Rout is the equivalent resistance after the source and drain resistance of power tube, feedback resistance and loaded impedance parallel connection, C
iNTthe output capacitance of LDO, g
mc1for the mutual conductance of NMOS tube Mc1 in charging path, g
mpfor the mutual conductance of power tube, R
1for the equivalent output impedance of previous stage, Kc is the Current amplifier scale-up factor of current mirror unit in charging path.Through deriving and simplifying, loop transfer function of the present utility model is as follows.
Fig. 6 is that of the present utility model powering on for transient response enhancing matrix in Fig. 2 holds the ac small signal zero-pole map of LDO circuit.As can be seen from loop transfer function and zero-pole map, because electric capacity doubly takes advantage of the effect with miller compensation, limit P1 and P2 is very open, and Left half-plane Z2 at zero point and limit P2 position very near, its effect can be cancelled out each other, because the Z1 at zero point of Left half-plane is positioned at high frequency, the phase margin of LDO can be improved to a certain extent.Adopt fast transient response path of the present utility model, the frequency response of LDO can be made to be similar to first-order system, in analyzing, do not consider power tube grid capacitance C
gDimpact, actual frequency domain characteristic is slightly worse than first-order system.Thus fast transient response path of the present utility model, while realizing fast transient response compensation, achieves frequency compensation well, can ensure that on sheet, LDO keeps stable in whole load current variation range.
The utility model is not limited to above-described embodiment, but can put into practice with amendment or the mode changed in the spirit and scope of claims.It will be apparent to those skilled in the art, when not departing from spirit of the present utility model or essential characteristic, the utility model can in other forms, structure, layout, ratio, and to realize with other assembly, material and parts.When not departing from the utility model scope and spirit, can other distortion be carried out here to disclosed embodiment and change.
Claims (3)
1. a transient response enhancing matrix powers on and holds LDO circuit, it is characterized in that, electric capacity CINT on the sheet comprising reference voltage source, error amplifier, power tube, resistance string partial pressure unit, charging path, discharge path, coupling capacitance Cc1 and Cc2 and 100pF; The negative terminal of error amplifier connects reference voltage source, the centre tap of the resistance string partial pressure unit that the positive termination of error amplifier is made up of R1 and R2, the grid of the output termination power tube of error amplifier, the input end of the drain electrode connecting resistance string partial pressure unit of power tube; Charging path is connected with coupling capacitance Cc2, and be connected across between the grid of power tube and drain electrode, discharge path is connected with coupling capacitance Cc1, is connected across between the grid of power tube and drain electrode; Electric capacity on the sheet of the output termination 100pF of described LDO circuit.
2. a kind of transient response enhancing matrix as claimed in claim 1 powers on and holds LDO circuit, it is characterized in that, described charging path is coupling capacitance Cc2 mono-termination LDO output voltage terminal, the drain electrode of another termination NMOS tube Mc1, NMOS tube Mc1 and NMOS tube Mc2 is connected into current lens unit, PMOS Mc3 and PMOS Mc4 is connected into current lens unit, the drain electrode of NMOS tube Mc2 connects grid and the drain electrode of PMOS Mc3, the drain electrode of PMOS Mc4 connects the grid of power tube, and current source I2 provides bias current for charging path.
3. a kind of transient response enhancing matrix as claimed in claim 1 powers on and holds LDO circuit, it is characterized in that, described discharge path is coupling capacitance Cc1 mono-termination LDO output voltage terminal, the source electrode of another termination NMOS tube Mf and the grid of NMOS tube Mb, the drain electrode of NMOS tube Mb connects the grid of NMOS tube Mf, and current source Ib and I1 provides bias current for discharge path.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520041773.4U CN204833032U (en) | 2015-01-21 | 2015-01-21 | Electric capacity LDO circuit in transient response reinforcing matrix |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520041773.4U CN204833032U (en) | 2015-01-21 | 2015-01-21 | Electric capacity LDO circuit in transient response reinforcing matrix |
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| Publication Number | Publication Date |
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| CN204833032U true CN204833032U (en) | 2015-12-02 |
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| CN201520041773.4U Expired - Fee Related CN204833032U (en) | 2015-01-21 | 2015-01-21 | Electric capacity LDO circuit in transient response reinforcing matrix |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107479610A (en) * | 2017-09-29 | 2017-12-15 | 北京智芯微电子科技有限公司 | A kind of quick response LDO circuit |
| CN108287588A (en) * | 2018-01-30 | 2018-07-17 | 上海华虹宏力半导体制造有限公司 | Voltage adjuster |
| TWI668550B (en) * | 2018-06-14 | 2019-08-11 | 華邦電子股份有限公司 | Current regulating circuit and method |
| CN110652302A (en) * | 2019-10-10 | 2020-01-07 | 中国人民解放军第四军医大学 | Knee vibration measuring instrument |
| CN110727308A (en) * | 2019-11-21 | 2020-01-24 | 华大半导体有限公司 | Auxiliary circuit suitable for no off-chip capacitance type voltage regulator |
| WO2021232426A1 (en) * | 2020-05-22 | 2021-11-25 | Telefonaktiebolaget Lm Ericsson (Publ) | Circuit and method for compensating output of voltage source, and voltage source |
| CN114879794A (en) * | 2022-05-25 | 2022-08-09 | 西安微电子技术研究所 | On-chip capacitor implementation circuit for LDO frequency compensation and LDO circuit |
-
2015
- 2015-01-21 CN CN201520041773.4U patent/CN204833032U/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107479610A (en) * | 2017-09-29 | 2017-12-15 | 北京智芯微电子科技有限公司 | A kind of quick response LDO circuit |
| CN108287588A (en) * | 2018-01-30 | 2018-07-17 | 上海华虹宏力半导体制造有限公司 | Voltage adjuster |
| TWI668550B (en) * | 2018-06-14 | 2019-08-11 | 華邦電子股份有限公司 | Current regulating circuit and method |
| CN110652302A (en) * | 2019-10-10 | 2020-01-07 | 中国人民解放军第四军医大学 | Knee vibration measuring instrument |
| CN110652302B (en) * | 2019-10-10 | 2023-03-14 | 中国人民解放军第四军医大学 | Knee vibration measuring instrument |
| CN110727308A (en) * | 2019-11-21 | 2020-01-24 | 华大半导体有限公司 | Auxiliary circuit suitable for no off-chip capacitance type voltage regulator |
| CN110727308B (en) * | 2019-11-21 | 2020-10-02 | 华大半导体有限公司 | Auxiliary circuit suitable for no off-chip capacitance type voltage regulator |
| WO2021232426A1 (en) * | 2020-05-22 | 2021-11-25 | Telefonaktiebolaget Lm Ericsson (Publ) | Circuit and method for compensating output of voltage source, and voltage source |
| CN114879794A (en) * | 2022-05-25 | 2022-08-09 | 西安微电子技术研究所 | On-chip capacitor implementation circuit for LDO frequency compensation and LDO circuit |
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| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20151202 Termination date: 20170121 |
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| CF01 | Termination of patent right due to non-payment of annual fee |