Full-symmetry positive and negative double-voltage output charge pump structureTechnical Field
The invention relates to the technical field of power supply circuits, in particular to a full-symmetrical positive and negative double voltage output charge pump structure.
Background
Various analog circuits often require the use of positive and negative power supplies, as well as different voltage values to power the circuit. Limited to other external power environments such as circuit boards, use environments are often encountered where there is only a single power source and the power supply voltage is below the desired value.
The charge pump circuit can boost the power supply voltage and change the polarity of the power supply voltage, and can be used as a conversion circuit between a single-power low-voltage power supply source and a high-voltage positive and negative power supply required by an actual analog circuit.
Disclosure of Invention
The invention aims to provide a full-symmetrical positive and negative double voltage output charge pump structure so as to solve the problems in the background technology.
In order to solve the technical problems, the invention provides a full-symmetrical positive and negative voltage doubling output charge pump structure, which comprises switches SW 1-SW 9, capacitors Cfly + and Cfly -, and capacitors Cout + and Cout -;
the first end of the switch SW1 is connected with the single power supply voltage VDD, and the second end is connected with the node voltage CPP; the first end of the switch SW6 and the first end of the switch SW7 are both connected with the node voltage CPP, the second end of the switch SW6 and the first end of the capacitor Cout + are both connected with the positive double voltage output VDD2P, and the second end of the capacitor Cout + is connected with the second end of the switch SW 7;
The first end of the switch SW2 is connected with the system ground GND, and the second end of the switch SW2 is connected with the node voltage CPN; the first end of the capacitor Cfly + is connected with the node voltage CPP, and the second end of the capacitor Cfly + is connected with the node voltage CPN; the first end of the switch SW5 is connected with the node voltage CPN, and the second end of the switch SW5 is connected with the node voltage CNP;
the first end of the switch SW3 is connected with the single power supply voltage VDD, and the second end of the switch SW3 is connected with the node voltage CNP; the first end of the switch SW4 is connected with the system ground GND, and the second end of the switch SW4 is connected with the node voltage CNN; the first end of the capacitor Cfly is connected with the node voltage CNP, and the second end is connected with the node voltage CNN; the first terminal of the switch SW8 and the first terminal of the switch SW9 are both connected to the node voltage CNN, the second terminal of the switch SW9 and the first terminal of the capacitor Cout -are both connected to the negative voltage doubler output VDD2N, and the second terminal of the capacitor Cout -is connected to the second terminal of the switch SW 8.
In one embodiment, the second terminal of the switch SW8 and the second terminal of the switch SW7, the second terminal of the capacitor Cout + and the second terminal of the capacitor Cout are all connected to the system ground GND.
In one embodiment, the working process of the fully symmetrical positive and negative voltage doubler output charge pump structure comprises four stages:
Stage one: the single power supply charges the capacitors Cfly + and Cfly -; at this stage, the switches SW1, SW2, SW3, SW4 are closed, and the switches SW5, SW6, SW7, SW8, SW9 are open; the single power supply charges the two ends of the capacitors Cfly + and Cfly to the voltage VDD, the node voltage CPN=CNN=GND, and the node voltage CPP=CNP=VDD; the charge held by the capacitors Cout + and Cout -is used for supplying power to a load;
Stage two: capacitors Cfly + and Cfly -charge capacitor Cout +; at this stage, the switches SW1, SW2, SW3, SW4, SW7, SW9 are open, and the switches SW5, SW6, SW8 are closed; capacitors Cfly + and Cfly -charge Cout +, node voltage cnn=gnd, node voltage cpn=cnp=vdd, vd2p=cpp=2×vdd;
Stage three: the single power supply charges the capacitors Cfly + and Cfly -; the switch states are the same as the node voltages in the first stage, the switches SW1, SW2, SW3 and SW4 are closed, and the switches SW5, SW6, SW7, SW8 and SW9 are opened;
Stage four: the capacitors Cfly + and Cfly -charge Cout -; at this stage, the switches SW1, SW2, SW3, SW4, SW6, SW8 are open, and the switches SW5, SW7, SW9 are closed; the capacitors Cfly + and Cfly -charge up to Cout -, the node voltage cpp=gnd, the node voltage cpn=cnp= -1×vdd, and vd2n=cnn= -2×vdd.
In one embodiment, the switches SW 1-SW 9 are controllable switches, the capacitors Cfly + and Cfly are charge pump intermediate capacitors, the capacitor Cout + is a positive output voltage stabilizing capacitor, and the capacitor Cout is a negative output voltage stabilizing capacitor.
The symmetrical structure can simplify the design flow, only one-time switch is needed to be designed, and two capacitance parameters are selected to finish the design; meanwhile, the fully symmetrical output characteristic can better meet the requirement of part of analog circuits on symmetrical power supplies, and the influence of the difference of positive and negative power supplies on the circuit performance is reduced.
Drawings
FIG. 1 is a schematic diagram of a fully symmetrical positive and negative voltage doubler output charge pump according to the present invention.
Detailed Description
The invention provides a full-symmetrical positive and negative double voltage output charge pump structure which is further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
The invention provides a full-symmetrical positive and negative voltage doubling output charge pump structure, which is shown in figure 1 and comprises switches SW 1-SW 9, capacitors Cfly + and Cfly -, and capacitors Cout + and Cout -.
The first end of the switch SW1 is connected with the single power supply voltage VDD, and the second end is connected with the node voltage CPP; the first end of the switch SW6 and the first end of the switch SW7 are both connected with the node voltage CPP, the second end of the switch SW6 and the first end of the capacitor Cout + are both connected with the positive two-time voltage output VDD2P, and the second end of the capacitor Cout + is connected with the second end of the switch SW 7.
The first end of the switch SW2 is connected with the system ground GND, and the second end of the switch SW2 is connected with the node voltage CPN; the first end of the capacitor Cfly + is connected with the node voltage CPP, and the second end of the capacitor Cfly + is connected with the node voltage CPN; the first terminal of the switch SW5 is connected to the node voltage CPN, and the second terminal is connected to the node voltage CNP.
The first end of the switch SW3 is connected with the single power supply voltage VDD, and the second end of the switch SW3 is connected with the node voltage CNP; the first terminal of the switch SW4 is connected to the system ground GND and the second terminal is connected to the node voltage CNN. The first terminal of the capacitor Cfly is connected to the node voltage CNP, and the second terminal is connected to the node voltage CNN. The first terminal of the switch SW8 and the first terminal of the switch SW9 are both connected to the node voltage CNN, the second terminal of the switch SW9 and the first terminal of the capacitor Cout -are both connected to the negative voltage doubler output VDD2N, and the second terminal of the capacitor Cout -is connected to the second terminal of the switch SW 8. The second terminal of switch SW8 and the second terminal of switch SW7, the second terminal of capacitor Cout + and the second terminal of capacitor Cout -are all connected to the system ground GND.
SW 1-SW 9 are controllable switches, Cfly + and Cfly -are charge pump intermediate capacitors, and Cout + and Cout -are positive and negative output voltage stabilizing capacitors.
The operation of the charge pump is divided into four phases, which are described in detail below:
Stage one: the single power supply charges the capacitors Cfly + and Cfly -. At this stage, the controllable switches SW1, SW2, SW3, SW4 are closed, and the controllable switches SW5, SW6, SW7, SW8, SW9 are opened. The single power supply charges both ends of the capacitors Cfly + and Cfly to the voltage VDD (without considering the on-resistance loss of the switch, the same applies hereinafter), the node voltage cpn=cnn=gnd, and the node voltage cpp=cnp=vdd. The charge held by the capacitors Cout + and Cout -powers the load.
Stage two: the capacitors Cfly + and Cfly -charge Cout +. At this stage, the controllable switches SW1, SW2, SW3, SW4, SW7, SW9 are open and the controllable switches SW5, SW6, SW8 are closed. The capacitors Cfly + and Cfly -charge Cout +, the node voltage cnn=gnd, the node voltage cpn=cnp=vdd, and VDD2 p=cpp=2×vdd.
Stage three: the single power supply charges the capacitors Cfly + and Cfly -. The switch states are the same as the node voltages at stage one, i.e., the controllable switches SW1, SW2, SW3, SW4 are closed and the controllable switches SW5, SW6, SW7, SW8, SW9 are opened.
Stage four: the capacitors Cfly + and Cfly -charge up to Cout -. At this stage, the controllable switches SW1, SW2, SW3, SW4, SW6, SW8 are open and the controllable switches SW5, SW7, SW9 are closed. The capacitors Cfly + and Cfly -charge up to Cout -, the node voltage cpp=gnd, the node voltage cpn=cnp= -1×vdd, and vd2n=cnn= -2×vdd.
The invention uses a fully symmetrical charge pump structure, can obtain positive and negative output double voltage power supply by single low voltage power supply conversion, and provides symmetrical double power supply for the circuit. The charge pump structure of the present invention includes nine switches and four capacitors. The nine switches can use the same electrical parameters in actual application, the capacitance selection type can be determined according to actual load power consumption, and Cfly+=Cfly-,Cout+=Cout -can be selected; the symmetrical positive and negative power supply output and the double voltage characteristic can meet the requirements of more analog circuits.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.