CN203278646U - Charge pump - Google Patents
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- CN203278646U CN203278646U CN 201320300336 CN201320300336U CN203278646U CN 203278646 U CN203278646 U CN 203278646U CN 201320300336 CN201320300336 CN 201320300336 CN 201320300336 U CN201320300336 U CN 201320300336U CN 203278646 U CN203278646 U CN 203278646U
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Abstract
The utility model discloses a charge pump, this charge pump have input, positive voltage output and negative voltage output and include a plurality of switches, wherein every switch in a plurality of switches has the series resistance value, the series resistance value of one of them switch of a plurality of switches is more than the twice of the series resistance value of other switches.
Description
Technical field
The utility model relates to power supply, and is concrete but be not limited to relate to and make negative output voltage follow the boosting charge pump of positive output voltage.
Background technology
A kind of charge pump be used for to receive input voltage and provides respectively higher than the positive output voltage of ground reference with lower than the negative output voltage of ground reference at two outputs.In some application scenarios, negative output voltage is required to follow well positive output voltage, that is to say, the absolute value of negative voltage need to be as far as possible near positive output voltage.And, the startup stage negative output voltage also need to follow well positive output voltage.
The utility model content
In order to solve a previously described problem or a plurality of problem, the utility model proposes a kind of charge pump that can make its negative output voltage follow positive output voltage.
According to an aspect of the present utility model, a kind of charge pump has input, positive voltage output end and negative voltage output, described charge pump comprises a plurality of switches, it is characterized in that each switch in described a plurality of switch has series impedance, the series impedance of one of them switch of described a plurality of switches is more than the twice of series impedance of other switch.Charge pump can further comprise the resistance control module, and this resistance control module has: first input end couples positive voltage output end; The second input couples the negative voltage output; And output, couple the series resistance of described one of them switch.
According to another aspect of the present utility model, a kind of boosting charge pump has input, positive voltage output end and negative voltage output, it is characterized in that charge pump comprises: inductance, have first end and the second end, and wherein first end couples input; The first switch has first end, the second end and control end, and wherein first end couples the second end of inductance, and the second end of the first switch couples with reference to ground; Second switch has first end, the second end and control end, and wherein the first end of second switch couples the second end of inductance, and the second end of second switch couples positive voltage output end; The first output capacitance has first end and the second end, and wherein the first end of the first output capacitance couples the second end of second switch, and the second end of the first output capacitance couples with reference to ground; Floating charge electric capacity has first end and the second end, and wherein the first end of floating charge electric capacity couples the second end of inductance; The 3rd switch has first end, the second end and control end, and wherein the first end of the 3rd switch couples the second end of floating charge electric capacity, and the second end of the 3rd switch couples the negative voltage output; The second output capacitance has first end and the second end, and wherein the first end of the second output capacitance couples the second end of the 3rd switch, and the second end of the second output capacitance couples with reference to ground; The 4th switch has first end, the second end and control end, and wherein the first end of the 4th switch couples the second end of floating charge electric capacity, and the second end of the 4th switch couples with reference to ground; And the resistance control module, have first input end, the second input and output, wherein first input end couples positive voltage output end, and the second input couples the negative voltage output, and output couples the control end of described second switch; Wherein the control end of the control end of the first switch and the 3rd switch couples first and drives signal, and the control end of the control end of second switch and the 4th switch couples second and drives signal.The transconductance type amplifying circuit can comprise: the transconductance type amplifying circuit has first input end, the second input and control end; The first resistance has first end and the second end, and wherein first end couples positive voltage output end, and the second end couples the first input end of transconductance type amplifying circuit; And second resistance, have first end and the second end, wherein first end couples the negative voltage output, and the second end couples the first input end of transconductance type amplifying circuit; Wherein the second input of transconductance type amplifying circuit couples with reference to ground, and the output of transconductance type amplifying circuit couples the control end of second switch.Wherein, the body diode of the body diode of second switch and the 4th switch can couple the under-voltage protection signal.Charge pump can further comprise the switch that is coupled between input and inductance first end, and the control end of described switch can couple the under-voltage protection signal.
According to another aspect of the present utility model, a kind of boosting charge pump has input, positive voltage output end and negative voltage output, it is characterized in that described boosting charge pump comprises: inductance, have first end and the second end, and wherein first end couples input; The first switch has first end, the second end and control end, and wherein first end couples the second end of inductance, and the second end of the first switch couples with reference to ground; Second switch has first end, the second end and control end, and wherein first end couples the second end of inductance, and the second end of second switch couples positive voltage output end; The first output capacitance has first end and the second end, and wherein first end couples the second end of second switch, and the second end of the first output capacitance end couples with reference to ground; Floating charge electric capacity has first end and the second end, and wherein first end couples the second end of inductance; The 3rd switch has first end, the second end and control end, and wherein first end couples the second end of floating charge electric capacity, and the second end of the 3rd switch couples the negative voltage output; The second output capacitance has first end and the second end, and wherein first end couples the second end of the 3rd switch, and the second end of the second output capacitance couples with reference to ground; The 4th switch has first end, the second end and control end, and wherein first end couples the second end of floating charge electric capacity, and the second end of the 4th switch couples with reference to ground; And discrete resistors, and second switch is connected in series; Wherein the control end of the control end of the first switch and the 3rd switch couples first and drives signal, and the control end of the control end of second switch and the 4th switch couples second and drives signal.Wherein second switch and the 4th switch can comprise transistor, and the transistor body diode of second switch and the transistor body diode of the 4th switch couple the under-voltage protection signal.Boosting charge pump can comprise the switch that is coupled between input and inductance first end, and the control end of described switch couples the under-voltage protection signal.
According to charge pump and the boosting charge pump that embodiment of the present utility model provides, can realize that negative output voltage follows the effect of positive output voltage well, and have simple in structure, be easy to the advantages such as regulating and controlling.
Description of drawings
In order better to understand the utility model, will be described embodiment of the present utility model according to the following drawings.These accompanying drawings only are used for example.Accompanying drawing only illustrates the Partial Feature of system in embodiment or circuit usually.
Fig. 1 shows the charge pump schematic diagram according to the utility model one embodiment;
Fig. 2 shows the charge pump schematic diagram according to the utility model one embodiment, and wherein this charge pump comprises the first output capacitance, the second output capacitance and floating charge electric capacity;
Fig. 3 shows the boosting charge pump circuit diagram according to the utility model one embodiment;
Fig. 4 A, Fig. 4 B, Fig. 4 C and Fig. 4 D show respectively a kind of charge pump circuit and drive control signal and two kinds of operating states, are used for explanation and follow the method for positive output voltage according to the negative output voltage that makes of the utility model one embodiment;
Fig. 5 shows transistorized boosting charge pump circuit diagrams a plurality of according to comprising of the utility model one embodiment;
Fig. 6 shows the circuit diagram that is subjected to the boosting charge pump of under-voltage protection (UVLO) signal controlling according to wherein two switching tubes of the utility model one embodiment;
Fig. 7 shows and one switch is coupled in the boosting charge pump circuit diagram of input according to the utility model one embodiment;
Fig. 8 shows the boosting charge pump circuit diagram that second switch and discrete resistors are connected in series according to the utility model one embodiment;
The signal waveforms when signal waveforms when Fig. 9 A and Fig. 9 B show respectively according to the stable state of boosting charge pump in the corresponding diagram 3 of the utility model one embodiment and startup;
Figure 10 shows the charge pump schematic diagram according to the employing feedback loop by-pass cock series resistance of the utility model one embodiment;
Figure 11 shows the circuit diagram of regulating the boosting charge pump of this switch series resistance according to the gate voltage that passes through to control a switch of the utility model one embodiment.
Run through institute's identical Reference numeral of drawings attached and represent same or analogous parts or feature.
Embodiment
The below will describe specific embodiment of the utility model in detail, should be noted that the embodiments described herein only is used for illustrating, and be not limited to the utility model.To in detailed description of the present utility model, in order to understand better the utility model, a large amount of details has been described below.Yet it will be understood by those skilled in the art that does not have these details, and the utility model can be implemented equally.In order to set forth the utility model clearly, this paper has simplified the detailed description of some concrete structures and function.In addition, the similar 26S Proteasome Structure and Function of having described in detail in certain embodiments repeats no more in other embodiments.Although every term of the present utility model is to describe one by one in conjunction with concrete example embodiment, these terms should not be construed as the demonstration execution mode that is confined to set forth here.
Fig. 1 shows the schematic diagram according to the charge pump 100 of the utility model one embodiment.Charge pump 100 has input 11, positive voltage output end 12 and negative voltage output 13.Wherein input 11 receives input voltage vin, and charge pump 100 converts input voltage vin to the positive output voltage V+ that exports at positive voltage output end 12 and the negative output voltage V-that exports at negative voltage output 13.In one embodiment, positive output voltage V+ is greater than input voltage vin.
The absolute value of negative output voltage V-need to equal or be approximately equal to positive output voltage V+, and in other words negative output voltage V-need to follow positive output voltage V+.A kind of method that makes negative output voltage V-follow positive output voltage V+ is included as a plurality of switches of charge pump and selects asymmetric series resistance.That is to say, the series impedance of a plurality of switches is not identical.In one embodiment, wherein the series impedance of certain switch greater than the twice of other any one switch series impedance.In one embodiment, maximum switch series impedance is greater than ten times of another switch series impedance.In one embodiment, series resistance is the conducting resistance of switch.In another embodiment, selecting asymmetric series resistance to comprise for a plurality of switches of charge pump is connected in series one of them switch in a discrete resistors and a plurality of switch.
Fig. 2 shows the schematic diagram according to the charge pump 200 of the utility model one embodiment.Charge pump 200 comprises the first module 24 that is couple to positive voltage output end 22 and the second module 25 that is couple to negative voltage output 23.The first module 24 comprises the first switch A1 and second switch B1.The second module 25 comprises the 3rd switch A2 and the 4th switch B2.Charge pump 200 further comprises a plurality of electric capacity.These a plurality of electric capacity comprise the first output capacitance C1, the second output capacitance C2 and floating charge electric capacity Cfly.Wherein the first output capacitance C1 is coupled between positive voltage output end 22 and reference ground GND and is used for providing positive output voltage V+.The second output capacitance C2 is coupled between negative voltage output 23 and reference ground GND and is used for providing negative output voltage V-.Floating charge electric capacity Cfly is coupled between the first module 24 and the second module 25.A plurality of switches of charge pump 200 comprise first group of switch A1 and A2, and second group of switch B1 and B2.Wherein the turn-on and turn-off state of first group of switch and second group of switch is complementary type.In very first time section in each switch periods, certain drives signal and is the first state, first group of switch comprises that the first switch A1 and the 3rd switch A2 turn-off, second group of switch comprises second switch B1 and the 4th switch B2 conducting, electric current flows to reference to ground GND from positive voltage output end 22, and the first output capacitance C1 is recharged; The second time period in this switch periods, this driving signal is the second state that is different from the first state logic level, and first group of switch comprises A1 and A2 conducting, and second group of switch comprises that B1 and B2 turn-off, electric current is discharged from flowing to negative voltage output 23, the second output capacitance C2 with reference to ground GND.In one embodiment, system the startup stage, the method that makes negative output voltage V-follow positive output voltage V+ further comprises and begins simultaneously the first output capacitance C1 and floating charge electric capacity Cfly are charged, and makes positive output voltage V+ and negative output voltage V-begin simultaneously to increase.
In one embodiment, charge pump 200 comprises a boosting charge pump.In one embodiment, be defined as input voltage vin the startup stage and rise to stage between a threshold voltage from null value.
Fig. 3 shows the circuit diagram according to the boosting charge pump 300 of the utility model one embodiment.Boosting charge pump 300 comprises inductance L, the first switch A1, second switch B1, the first output capacitance C1, floating charge electric capacity Cfly, the 3rd switch A2, the second output capacitance C2 and the 4th switch B2.Inductance L has first end 311 and the second end 312, and wherein first end 311 couples input 31.The first switch A1 has first end 321, the second end 322 and control end, and wherein first end 321 the second end 312, the second ends 322 of coupling inductance L couple with reference to ground GND.Second switch B1 has first end 323, the second end 324 and control end, and wherein first end 323 the second end 312, the second ends 324 of coupling inductance L couple positive voltage output end 32.The first output capacitance C1 has first end 325 and the second end 326, and wherein first end 325 the second end 324, the second ends 326 of coupling second switch B1 couple with reference to ground GND.Floating charge electric capacity Cfly has first end 331 and the second end 332, and wherein first end 331 couples the second end 312 of inductance L.The 3rd switch A2 has first end 335, the second end 336 and control end, and wherein first end 335 the second end 332, the second ends 336 of coupling floating charge electric capacity Cfly couple negative voltage output 33.The second output capacitance C2 has first end 337 and the second end 338, and wherein first end 337 the second end 336, the second ends 338 of coupling the 3rd switch A2 couple with reference to ground GND.The 4th switch B2 has first end 333, the second end 334 and control end, and wherein first end 333 the second end 332, the second ends 334 of coupling floating charge electric capacity Cfly couple with reference to ground GND.Each switch A1, B1, A2 or B2 and a series connection resistance couple, and are respectively resistance R a1, Rb1, Ra2 and Rb2.In one embodiment, resistance R a1, Rb1, Ra2 and Rb2 are respectively the conducting resistance of switch A1, B1, A2 and B2.In the very first time of switch periods section, second switch B1 and the 4th switch B2 conducting, the first switch A1 and the 3rd switch A2 turn-off, and the first output capacitance C1 is recharged, and positive output voltage V+ rises.Within the second time period of switch periods, the first switch A1 and the 3rd switch A2 conducting, second switch B1 and the 4th switch B2 turn-off, and the second output capacitance C2 is discharged, and negative output voltage V-absolute value rises.Charge pump can have the topology that is different from charge pump in Fig. 3.For example, each switch can comprise the switch of a plurality of parallel connections, and perhaps each electric capacity can comprise a capacitance network.
Fig. 4 A, Fig. 4 B, Fig. 4 C and Fig. 4 D show boosting charge pump 400A, and it drives signal (S1 and S2) and different operating states accordingly, are used for illustrating that the negative output voltage V-that makes according to the utility model one embodiment follows the method for positive output voltage V+.Boosting charge pump 400A has the topology identical with boosting charge pump 300 in Fig. 3, for the sake of simplicity, will no longer give unnecessary details its annexation.In boosting charge pump 400A, the control end of the control end of the first switch A1 and the 3rd switch A2 is coupled to first and drives signal S1.The control end of the control end of second switch B1 and the 4th switch B2 is coupled to second and drives signal S2.
As shown in Figure 4 B, the second driving signal S2 and the first driving signal S1 are complementary relationship.In the very first time of switch periods T stage D T, the first driving signal S1 is the first state such as logic low, and the second driving signal S2 is that the second state is as high in logic.Correspondingly, second group of switch comprises second switch B1 and the 4th switch B2 conducting, and first group of switch comprises that the first switch A1 and the 3rd switch A2 turn-off, as shown in the schematic diagram of Fig. 4 C.Within this time period, current Ib 1 flows to positive voltage output end 32, the first output capacitance C1 from inductance L by second switch B1 and is recharged, and positive output voltage V+ raises; Simultaneously, current Ib 2 flows to reference to ground GND from inductance L by floating charge electric capacity Cfly and the 4th switch B2, and floating charge electric capacity Cfly is recharged.In this stage,
Ib1*(1-D)=I
o+ (1)
Ib1+Ib2=I
L (2)
V
++Ib1*Rb1=V
cfly+Ib2*Rb2 (3)
Wherein D is for driving the duty ratio of signal S2, and Io+ is the output current of positive voltage output end, and IL is the electric current that flows through inductance L, and Vcfly is the voltage difference at floating charge electric capacity Cfly two ends.
In other time phase (1-D) T of this switch periods T, referring to Fig. 4 B, it is high that the first driving signal S1 changes logic into, second drives signal S2 changes logic low into, therefore, first group of switch comprises that the first switch A1 and the 3rd switch A2 are switched on, and second group of switch comprises that second switch B1 and the 4th switch B2 are turned off.In this stage, referring to the schematic diagram 400D of Fig. 4 D, electric current I a1 flows to reference to ground GND from inductance L by the first switch A1; Simultaneously, electric current I a2 flows to the first switch A1 by the 3rd switch A2 and floating charge electric capacity Cfly from reference ground GND, and the second output capacitance C2 and floating charge electric capacity Cfly are discharged.In this stage,
Ia2*D=I
o- (4)
Vcfly=V
-+Ra2*Ia2+(I
L+Ia2)*Ra1 (5)
Wherein Io-is the output current of negative voltage output, and wherein V-represents the absolute value of negative output voltage here.
In a switch periods, the current design that flows through floating charge electric capacity Cfly is poised state, that is:
Ib2*(1-D)=Ia2*D (6)
In conjunction with formula (1) to formula (6), can derive:
As shown from the above formula, negative output voltage absolute value V-raises along with the rising of resistance value Rb1, and negative output voltage absolute value V-is along with other resistance values Ra1, the rising of Ra2 and Rb2 and reducing.In order to make negative output voltage V-can follow positive output voltage V+, absolute value and the positive output voltage V+ approximately equal in order to make negative output voltage in other words needs to satisfy:
Above-mentioned formula can be by selecting asymmetric switch series connection resistance R a1, and Ra2, Rb1 and Rb2 realize, namely selector switch B1 has higher series impedance Rb1, and selector switch A1, A2 and B2 have lower series impedance Ra1, Ra2 and Rb2.By second switch B1 and other switches A1, A2 and B2 are selected asymmetric series impedance, the difference between positive output voltage V+ and negative output voltage absolute value V-can be reduced.In one embodiment, resistance value Rb1=3 ohm, resistance value Ra1=0.45 ohm, resistance value Ra2=Rb2=0.5 ohm.
Fig. 5 shows the charge pump embodiment circuit diagram according to the utility model one embodiment, and wherein charge pump 500 comprises a plurality of switch A1, A2, B1 and B2.Charge pump 300 in topological sum Fig. 3 of charge pump 500 is similar, for the sake of simplicity, the concrete annexation to charge pump 500 is no longer given unnecessary details.In charge pump 500, each switch A1, A2, B1 or B2 comprise a transistor, asymmetric series resistance Ra1 wherein, and Ra2, Rb1 and Rb2 derive from each transistorized conducting resistance.Each further comprises an individual diodes each transistor A1, B1, A2 or B2.In one embodiment, the conducting resistance Rb1 of second switch B1 is greater than conductor resistance Ra1, Ra2 and the Rb2 of other switches.The higher conducting resistance Rb1 of semiconductor transistor B1 can realize by being different from other transistorized manufacture craft, as by adopting different doping contents or different Butut sizes to realize to transistor B1.In the embodiment shown in fig. 5, each transistor comprises metal oxide semiconductor field effect tube (MOSFET).The transistor such as the junction field effect transistor (JFET) that should be known in other form also can not break away from purport of the present utility model and be used in embodiment of the present utility model.
Fig. 6 shows the schematic diagram according to the boosting charge pump 600 of the utility model one embodiment, wherein two of charge pump 600 switch B1 and B2 be subjected to the UVLO signal controlling be used for the startup stage realize that negative output voltage V-follows positive output voltage V+ well.Charge pump 300 in topological sum Fig. 3 of charge pump 600 is similar, for the sake of simplicity, the concrete annexation to charge pump 600 is no longer given unnecessary details.Boosting charge pump 600 comprises a plurality of switch A1, A2, B1 and B2, and wherein each switch comprises a MOSFET pipe.Each MOSFET pipe A1, A2, B1 or B2 can comprise a plurality of transistor units that are produced on Semiconductor substrate.Each transistor such as transistor A1 have conducting resistance Ra1 and be coupled in source electrode and the drain electrode between body diode.Resistance when wherein conducting resistance is the conducting of MOSFET pipe between source electrode and drain electrode.Signal UVLO is coupled to the body diode that transistor B1 and B2 are used for blocking-up transistor B1 and B2 under initial condition.Signal UVLO is in effective status during lower than a threshold voltage in input voltage vin.When signal UVLO is in effective status, as logic high, the control end of transistor A1, B1, A2 and B2 is not driven signal controlling, simultaneously, the body diode of second switch B1 and the 4th switch B2 is blocked, and makes switch A1, B1, A2 and B2 not have electric current to flow through.Correspondingly, do not have electric current that the first output capacitance C1 and floating charge electric capacity Cfly are charged.When signal UVLO becomes disarmed state, for example drop to threshold voltage in input voltage vin and become logic low when following, drive signal and begin control switch A1, B1, A2 and B2, make first group of switch (A1, A2) and second group of switch (B1, B2) alternate conduction, the body diode of second switch B1 and the 4th switch B2 is open-minded simultaneously.In other words, when switch A1, A2, B1 and B2 were turned off, the body diode of second switch B1 and the 4th switch B2 also was blocked simultaneously.The body diode of second switch B1 and the 4th switch B2 stops blocking-up when switch works.Therefore positive output voltage V+ and the negative output voltage V-increase of starting from scratch simultaneously when the boosted charge pump startup, make negative output voltage V-the startup stage can follow well positive output voltage V+.
Fig. 7 shows boosting charge pump 700 circuit diagrams according to the utility model one embodiment, and wherein boosting charge pump 700 comprises that one is coupled in the K switch between input 71 and inductance.Charge pump 300 in topological sum Fig. 3 of charge pump 700 is similar, for the sake of simplicity, no longer the concrete annexation of charge pump 700 is given unnecessary details.Boosting charge pump 700 further comprises the K switch that is coupled between input 71 and inductance L.For the startup stage make negative output voltage V-follow positive output voltage V+, K switch is in off state under initial condition, make inductance L before circuit start and input 71 disconnects.In one embodiment, the control end of K switch couples the UVLO signal.The startup stage, signal UVLO is in effective status, switch A1, B1, A2, B2 and K are in off state.Above-mentioned more than threshold voltage when input voltage vin, UVLO becomes disarmed state, the K switch conducting, and inductance L couples input 71.Simultaneously, switch A1, A2, B1 and B2 also start working.Correspondingly, the first output capacitance C1 and floating charge electric capacity Cfly can begin charging simultaneously, and negative output voltage V-follows positive output voltage V+ and begins simultaneously to increase.Therefore negative output voltage V-the startup stage can follow well positive output voltage V+.
Fig. 8 shows the boosting charge pump 800 according to the utility model one embodiment, the wherein second switch B1 of charge pump 800 and discrete resistors Rb1 series connection.Boosting charge pump 800 has the input 81 of the input voltage vin of coupling, the positive voltage output end 82 of positive output voltage V+ is provided, the negative voltage output 83 of negative output voltage V-is provided, inductance L, the first switch A1, second switch B1, the 3rd switch A2, the 4th switch B2, floating charge electric capacity Cfly, the first output capacitance C1, the second output capacitance C2 and resistance R b1.Boosting charge pump 300 in topological sum Fig. 3 of boosting charge pump 800 is similar, and for ease of describing, its similarity is no longer given unnecessary details.Difference is that further with one discrete resistors Rb1 of second switch B1 is connected in series.Should be known in that other switch A1, A2 and B2 also can have conducting resistance.Yet the series resistance Rb1 that second switch B1 is corresponding specially makes in order to have than the larger series impedance of other switches.
In another embodiment, the series resistance Rb1 that specially makes is integrated on the identical Semiconductor substrate of making second switch B1 by special Butut size or doping content.
Therefore, second switch B1 has the series resistance higher than other switch, and the asymmetric resistance value of these switches makes negative output voltage V-can follow well positive output voltage V+.
In the embodiment shown in fig. 8, coupled K switch between the first end of input 81 and inductance L, and under the initial condition that switch A1, A2, B1 and B2 turn-off, K switch also is in off state; When switch A1, A2, B1 and B2 began switch motion, K switch was switched on.Like this, the first output capacitance C1 and floating charge electric capacity Cfly begin charging simultaneously, the startup stage also realized well the Following effect of negative voltage and positive voltage.Should be known in that in Fig. 8, the K switch of boosting charge pump is optional.In one embodiment, for the startup stage realize good Following effect, as described in top chapters and sections, signal UVLO be coupled to second switch B1 and the 4th switch B2 be used for the startup stage blocking-up second switch B1 and the 4th switch B2 body diode.
Fig. 9 A and Fig. 9 B show respectively according to the simulation waveform figure under the stable state of boosting charge pump 300 in employing Fig. 3 of the utility model one embodiment and the startup stage simulation waveform figure.In this embodiment, input voltage vin=3.6 volt, Io+=Io-=10mA, Rb1=3 ohm, Ra1=0.45 ohm, Rb2=Ra2=0.5 ohm.Can see under the stable state situation of Fig. 9 A, negative output voltage V-fluctuates between-5.41 volts to-5.44 volts, and positive output voltage V+ fluctuates between 5.43 volts to 5.45 volts.Difference percentage between positive output voltage and negative output voltage absolute value is less than 0.3%, realized that as seen negative output voltage follows the effect of positive output voltage well.Specifically, when the driving signal S1 on putting on the first switch A1 and the 3rd switch A2 control end is high level, switch A1 and A2 conducting, switch B1 and B2 turn-off.At this moment, the second output capacitance C2 discharge, the absolute value of negative output voltage V-raises.Simultaneously, inductive current IL raises, and the first output capacitance C1 is by load discharge, and positive output voltage V+ reduces.
When driving signal S1 step-down level, switch B1 and B2 conducting, switch A1 and A2 turn-off, at this moment, and the first output capacitance charging, positive output voltage V+ raises, and simultaneously, inductive current IL descends, and the absolute value of negative output voltage V-descends.
Shown in Fig. 9 B the startup stage, can see negative output voltage V-and the positive output voltage V+ increase of almost starting from scratch simultaneously, negative output voltage V-follows the variation of positive output voltage V+ well, and the difference between the absolute value of positive output voltage V+ and negative output voltage V-is very little.
In one embodiment, the load of positive voltage output end is different with the load of negative voltage output, the input voltage vin in this embodiment=4.2 volts wherein, the load current Io+=20mA of positive voltage output end, the load current Io-=14mA of negative voltage output, resistance R b1=0.45 ohm, resistance R b2=Ra2=0.5 ohm.The positive output voltage that emulation obtains and the difference percentage between the negative output voltage absolute value are less than 1%.Explanation is according to the charge pump of the utility model one embodiment, and the laod unbalance situation of its positive voltage output end and negative voltage output can be compensated well.
Figure 10 shows the charge pump 1000 according to the utility model one embodiment, and wherein the series resistance R resistance of charge pump 1000 switch is adjustable by feedback loop when switch conduction.For making description succinctly clear, the same or analogous part of charge pump 300 in charge pump 1000 and Fig. 3 is no longer given unnecessary details.When second switch B1 and the 4th switch B2 conducting, and the resistance of the resistance R of second switch B1 series connection regulates according to negative output voltage V-and positive output voltage V+, makes negative output voltage V-follow positive output voltage V+.In the embodiment shown in fig. 10, charge pump 1000 comprises the feedback loop that contains resistance control module 101.Resistance control module 101 has first input end 1011, the second input 1012 and output 1013, wherein first input end 1011 couples positive voltage output end 32 for receiving positive output voltage V+, the second input 1012 couples negative voltage output 33 and is used for receiving negative output voltage V-, and output 1013 is used for adjusting the resistance of the resistance R of connecting with second switch B1.Like this, resistance R is regulated based on the difference of positive output voltage V+ and negative output voltage V-absolute value.
In illustrated embodiment, during less than positive output voltage, increase the resistance of resistance R when the absolute value of negative output voltage V-, make the absolute value of negative output voltage increase; When negative output voltage V-surpasses the value of positive output voltage, reduce the resistance of resistance R to reduce the absolute value of negative output voltage.In one embodiment, switch B1 is transistor, and when second switch B1 conducting, the driving signal of controlling second switch B1 control end is high-impedance state, and the amplifying signal AMP that adopts resistance control module output 1013 to export controls the gate pole of second switch B1; When second switch B1 turn-offed, signal AMP was dragged down shielding by logic low such as ground reference.Should be known in that charge pump also can adopt other topology, the resistance of the series resistance of certain switch in charge pump can be regulated according to positive output voltage and negative output voltage.In one embodiment, the series resistance R that this resistance is adjustable is a discrete resistors, resistance R b1 as shown in Figure 8.In another embodiment, the series resistance that this resistance is adjustable is the conducting resistance to inductive switch, and this resistance realizes by the gate voltage of control switch.
Figure 11 shows the circuit diagram according to the charge pump 1100 of the utility model one embodiment, and wherein the series resistance of a switch is regulated by the gate voltage of controlling this switch.For making description simply clear, the feature that the charge pump 1100 in this embodiment is identical with charge pump 300 in Fig. 3 will no longer be given unnecessary details.The second switch B1 of charge pump 1100 comprises a transistor and has conducting resistance.Compare with the charge pump 300 in Fig. 3, charge pump 1100 further comprises a resistance control module 110.Resistance control module 110 comprises the first input end 1011 that receives positive output voltage V+, receives the second input 1012 of negative output voltage V-and couple for example output 1013 of gate pole of second switch B1 control end.In illustrated embodiment, resistance control module 110 comprises the first resistance R 1, the second resistance R 2 and transconductance type amplifying circuit 111.One end of the first resistance R 1 couples positive voltage output end 32 and is used for receiving positive output voltage V+, and the other end couples the inverting input of transconductance type amplifying circuit 111.The second resistance R 2 one ends couple negative voltage output 33 and are used for receiving negative output voltage V-, and the other end also couples the inverting input of transconductance type amplifying circuit 111.
Like this, transconductance type amplifying circuit 111 receives the difference signal between positive output voltage V+ and negative output voltage V-absolute value, and according to the gate pole of this difference output one amplifying signal AMP to transistor B1.During less than positive output voltage V+, the conducting resistance that output signal AMP controls transistor B1 increases when the absolute value of negative output voltage V-.In illustrated embodiment, transistor B1 comprises N-type MOSFET pipe, and the conducting resistance of transistor B1 increases when control signal AMP reduces.In another embodiment, when control signal AMP increased, the conducting resistance of switch B1 increased.During higher than positive output voltage V+, the conducting resistance that output signal AMP regulates transistor B1 reduces when the absolute value of negative output voltage V-.Transconductance type amplifying circuit 111 further has the in-phase input end and the output that control signal AMP is provided that couples with reference to ground.Resistance R 1 and R2 have identical or approaching resistance.During less than positive output voltage V+, the anti-phase input terminal potential of transconductance type amplifying circuit 111 is current potential above Ground when the absolute value of negative output voltage V-.Therefore signal AMP descends, and the conducting resistance of transistor B1 increases, and correspondingly, the absolute value of negative output voltage V-increases.If the absolute value of negative output voltage V-is higher than positive output voltage V+, the anti-phase input terminal voltage of transconductance type amplifying circuit 111 is negative voltage, lower than the ground reference of in-phase input end.Therefore, signal AMP increases, and the conducting resistance of transistor B1 reduces.Correspondingly, the absolute value of negative output voltage V-descends.In illustrated embodiment, resistance control module 110 further comprises capacitor C 3, capacitor C 4 and resistance R 3, and the current signal that the transconductance type amplifying circuit is exported is converted to voltage signal.Yet in other embodiments, resistance control module 110 can not comprise resistance and electric capacity, and perhaps resistance and electric capacity adopt other connected mode.
In another embodiment, resistance R 1 and R2 be coupled to transconductance type amplifying circuit 111 in-phase input end and with reference to couple the inverting input of transconductance type amplifying circuit 111.In yet another embodiment, an input of transconductance type amplifying circuit 111 receives negative output voltage V-, and another input couples positive output voltage V+, and the difference between negative output voltage V-and positive output voltage V+ is amplified.In certain embodiments, second switch B1 can comprise P type MOSFET pipe, the transistor of JFET pipe or other type.Should be known in that the resistance control module can have many different structures and realize increasing the function of the conducting resistance of transistor B1 when the relative negative output voltage absolute value of positive output voltage increases.
What need statement is that above-mentioned utility model content and embodiment are intended to prove the practical application of technical scheme that the utility model provides, and should not be construed as the restriction to the utility model protection range.Those skilled in the art are in spirit of the present utility model and principle, when doing various modifications, being equal to and replacing or improve.Protection range of the present utility model is as the criterion with appended claims.
Claims (10)
1. charge pump, have input, positive voltage output end and negative voltage output, described charge pump comprises a plurality of switches, it is characterized in that each switch in described a plurality of switch has series impedance, the series impedance of one of them switch of described a plurality of switches is more than the twice of series impedance of other switch.
2. charge pump as claimed in claim 1, is characterized in that further comprising the resistance control module, and this resistance control module has:
First input end couples positive voltage output end;
The second input couples the negative voltage output; And
Output couples the series resistance of described one of them switch.
3. a boosting charge pump, have input, positive voltage output end and negative voltage output, it is characterized in that charge pump comprises:
Inductance has first end and the second end, and wherein first end couples input;
The first switch has first end, the second end and control end, and wherein first end couples the second end of inductance, and the second end of the first switch couples with reference to ground;
Second switch has first end, the second end and control end, and wherein the first end of second switch couples the second end of inductance, and the second end of second switch couples positive voltage output end;
The first output capacitance has first end and the second end, and wherein the first end of the first output capacitance couples the second end of second switch, and the second end of the first output capacitance couples with reference to ground;
Floating charge electric capacity has first end and the second end, and wherein the first end of floating charge electric capacity couples the second end of inductance;
The 3rd switch has first end, the second end and control end, and wherein the first end of the 3rd switch couples the second end of floating charge electric capacity, and the second end of the 3rd switch couples the negative voltage output;
The second output capacitance has first end and the second end, and wherein the first end of the second output capacitance couples the second end of the 3rd switch, and the second end of the second output capacitance couples with reference to ground;
The 4th switch has first end, the second end and control end, and wherein the first end of the 4th switch couples the second end of floating charge electric capacity, and the second end of the 4th switch couples with reference to ground; And
The resistance control module has first input end, the second input and output, and wherein first input end couples positive voltage output end, and the second input couples the negative voltage output, and output couples the control end of described second switch;
Wherein the control end of the control end of the first switch and the 3rd switch couples first and drives signal, and the control end of the control end of second switch and the 4th switch couples second and drives signal.
4. boosting charge pump as claimed in claim 3 is characterized in that the resistance control module comprises:
The transconductance type amplifying circuit has first input end, the second input and control end;
The first resistance has first end and the second end, and wherein first end couples positive voltage output end, and the second end couples the first input end of transconductance type amplifying circuit; And
The second resistance has first end and the second end, and wherein first end couples the negative voltage output, and the second end couples the first input end of transconductance type amplifying circuit;
Wherein the second input of transconductance type amplifying circuit couples with reference to ground, and the output of transconductance type amplifying circuit couples the control end of second switch.
5. boosting charge pump as claimed in claim 3, is characterized in that the body diode of second switch and the body diode of the 4th switch couple the under-voltage protection signal.
6. boosting charge pump as claimed in claim 3, is characterized in that further comprising the switch that is coupled between input and inductance first end.
7. boosting charge pump as claimed in claim 6, is characterized in that the control end of described switch couples the under-voltage protection signal.
8. a boosting charge pump, have input, positive voltage output end and negative voltage output, it is characterized in that described boosting charge pump comprises:
Inductance has first end and the second end, and wherein first end couples input;
The first switch has first end, the second end and control end, and wherein first end couples the second end of inductance, and the second end of the first switch couples with reference to ground;
Second switch has first end, the second end and control end, and wherein first end couples the second end of inductance, and the second end of second switch couples positive voltage output end;
The first output capacitance has first end and the second end, and wherein first end couples the second end of second switch, and the second end of the first output capacitance end couples with reference to ground;
Floating charge electric capacity has first end and the second end, and wherein first end couples the second end of inductance;
The 3rd switch has first end, the second end and control end, and wherein first end couples the second end of floating charge electric capacity, and the second end of the 3rd switch couples the negative voltage output;
The second output capacitance has first end and the second end, and wherein first end couples the second end of the 3rd switch, and the second end of the second output capacitance couples with reference to ground;
The 4th switch has first end, the second end and control end, and wherein first end couples the second end of floating charge electric capacity, and the second end of the 4th switch couples with reference to ground; And
Discrete resistors, and second switch is connected in series;
Wherein the control end of the control end of the first switch and the 3rd switch couples first and drives signal, and the control end of the control end of second switch and the 4th switch couples second and drives signal.
9. boosting charge pump as claimed in claim 8, is characterized in that second switch and the 4th switch comprise transistor, and the transistor body diode of second switch and the transistor body diode of the 4th switch couple the under-voltage protection signal.
10. boosting charge pump as claimed in claim 8, is characterized in that further comprising the switch that is coupled between input and inductance first end, and the control end of described switch couples the under-voltage protection signal.
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| CN 201320300336 CN203278646U (en) | 2013-05-29 | 2013-05-29 | Charge pump |
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| CN 201320300336 CN203278646U (en) | 2013-05-29 | 2013-05-29 | Charge pump |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103280967A (en) * | 2013-05-29 | 2013-09-04 | 成都芯源系统有限公司 | Charge pump and method for enabling negative output voltage of charge pump to follow positive output voltage |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103280967A (en) * | 2013-05-29 | 2013-09-04 | 成都芯源系统有限公司 | Charge pump and method for enabling negative output voltage of charge pump to follow positive output voltage |
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