Positive and negative voltage source driving circuit

Abstract

The invention discloses a positive and negative voltage source driving circuit which is used for providing stable and accurate positive and negative voltages for a load circuit and saving the area of a chip and energy consumption during working. The circuit is characterized by comprising an operational amplifier, a transistor, a first resistor string, a second resistor string, a variable component, a first multiplexer and a second multiplexer, and the positive voltage operational amplifier and the negative voltage operational amplifier respectively output a positive voltage and a negative voltage to the load circuit.

Description

[0001] This application is a divisional application of the invention patent application with application number 2025101767042 and titled “Positive and Negative Voltage Source Driving Circuit”. The filing date of the original application is February 18, 2025. Technical Field

[0002] The present application belongs to the field of positive and negative voltage reference voltage generating circuits, and relates to the design of positive and negative voltage source driving circuits of liquid crystal displays. Background Art

[0003] Liquid crystal display is one of the common output devices in modern electronic systems. Liquid crystal display contains many liquid crystal units. Applying a voltage across each liquid crystal unit can control the light transmittance of the liquid crystal unit, and thus display different grayscales. By controlling the grayscale settings of the three primary colors separately, the color of each pixel can be controlled.

[0004] In order to control the voltage across a liquid crystal unit or other load circuit, a positive and negative voltage source driving circuit is required. In order to save energy and cost, a design with a smaller chip area is urgently needed. In addition to saving cost, it can also save the power consumed by the positive and negative voltage source driving circuit. Summary of the invention

[0005] The present application proposes a reference voltage generating circuit and a positive and negative voltage source driving circuit and a liquid crystal display using the reference voltage generating circuit to address the deficiencies in the prior art. The purpose is to provide a load circuit with stable and accurate positive and negative voltages, and to save chip area and energy consumption during operation, increase product competitiveness, and promote environmental protection.

[0006] In order to achieve the above purpose, this application adopts the following technical solutions:

[0007] According to an embodiment of the present application, a reference voltage generating circuit is provided, characterized in that it includes: an operational amplifier, whose first input terminal is used to receive a positive reference voltage +VREF; a transistor, whose gate is connected to the output terminal of the operational amplifier, and whose source is connected to the second input terminal of the operational amplifier and the first end of a first resistor string; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages; a current mirror, operating between a positive voltage VSP and a negative voltage VSN, and the current mirror is connected to the drain of the transistor and the second end of the second resistor string; and the second resistor string, the second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages, wherein the first end of the second resistor string and the second end of the first resistor string are connected to a ground potential GND.

[0008] Furthermore, in order to provide positive voltage and negative voltage simultaneously, it is characterized in that the multiple different first voltages are respectively located between the positive voltage VSP and the ground potential GND, and the multiple different first voltages are respectively located between the ground potential GND and the negative voltage VSN.

[0009] Furthermore, in order to select one from a plurality of positive voltages and a plurality of negative voltages as a positive voltage reference voltage VREF_VGMP and a negative voltage reference voltage VREF_VGMN, it is characterized in that the above-mentioned reference voltage generating circuit also includes a first multiplexer and a second multiplexer, the first multiplexer is used to receive the plurality of different first voltages, and select one from the plurality of different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, the second multiplexer is used to receive the plurality of different second voltages, and select one from the plurality of different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier.

[0010] Furthermore, in order to obtain a temperature-stable reference power supply, it is characterized in that the positive reference voltage +VREF is derived from a bandgap reference circuit, and the bandgap reference circuit operates between the positive voltage VSP and the ground potential GND.

[0011] Furthermore, in order to better output the negative voltage, it is characterized in that the above-mentioned current mirror is a current mirror with four transistors.

[0012] According to an embodiment of the present application, a positive and negative voltage source driving circuit is provided, characterized in that it includes: a bandgap reference circuit, which works between a positive voltage VSP and a ground potential GND, and is used to provide a positive reference voltage +VREF; a reference voltage generating circuit, which is used to receive the positive reference voltage +VREF and output a positive voltage reference voltage VREF_VGMP to a positive voltage operational amplifier and output a negative voltage reference voltage VREF_VGMN to a negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier, which respectively output a positive voltage and a negative voltage to a load circuit.

[0013] Furthermore, in order to select one from a plurality of positive voltages and a plurality of negative voltages as a positive voltage reference voltage VREF_VGMP and a negative voltage reference voltage VREF_VGMN, it is characterized in that the above-mentioned reference voltage generating circuit also includes a first multiplexer and a second multiplexer, and the reference voltage generating circuit is used to receive the positive reference voltage +VREF to generate a plurality of different first voltages and a plurality of different second voltages to the first multiplexer and the second multiplexer respectively, and the first multiplexer selects one from the plurality of different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, and the second multiplexer selects one from the plurality of different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier.

[0014] Furthermore, in order to provide positive voltage and negative voltage simultaneously, it is characterized in that the multiple different first voltages are respectively located between the positive voltage VSP and the ground potential GND, and the multiple different first voltages are respectively located between the ground potential GND and the negative voltage VSN.

[0015] Furthermore, in order to make the reference voltage generating circuit not need to have two similar circuits, only a single operational amplifier is needed to save chip area and power consumption, it is characterized in that the above-mentioned reference voltage generating circuit also includes: an operational amplifier, whose first input terminal is used to receive the positive reference voltage +VREF; a transistor, whose gate is connected to the output terminal of the operational amplifier, and whose source is connected to the second input terminal of the operational amplifier and the first end of the first resistor string; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output the plurality of different first voltages; a current mirror, working between the positive voltage VSP and the negative voltage VSN, the current mirror is connected to the drain of the transistor and the second end of the second resistor string; the first end of the second resistor string and the first end of the first resistor string are connected to the ground potential GND, the second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output the plurality of different second voltages.

[0016] Furthermore, in order to better output the negative voltage, it is characterized in that the above-mentioned current mirror is a current mirror with four transistors.

[0017] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0018] According to an embodiment of the present application, a liquid crystal display is provided, characterized in that it includes: a plurality of liquid crystal units; a plurality of liquid crystal control units respectively controlling the plurality of liquid crystal units; and a positive and negative voltage source driving circuit, wherein the positive and negative voltage source driving circuit includes: a bandgap reference circuit, operating between a positive voltage VSP and a ground potential GND, for providing a positive reference voltage +VREF; a reference voltage generating circuit, for receiving the positive reference voltage +VREF and outputting a positive voltage reference voltage VREF_VGMP to a positive voltage operational amplifier and outputting a negative voltage reference voltage VREF_VGMN to a negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier, respectively outputting a positive voltage and a negative voltage to one of the plurality of liquid crystal control units, for controlling the grayscale level of one of the plurality of liquid crystal units.

[0019] Furthermore, in order to select one from a plurality of positive voltages and a plurality of negative voltages as a positive voltage reference voltage VREF_VGMP and a negative voltage reference voltage VREF_VGMN, it is characterized in that the above-mentioned reference voltage generating circuit also includes a first multiplexer and a second multiplexer, and the reference voltage generating circuit is used to receive the positive reference voltage +VREF to generate a plurality of different first voltages and a plurality of different second voltages to the first multiplexer and the second multiplexer respectively, and the first multiplexer selects one from the plurality of different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, and the second multiplexer selects one from the plurality of different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier.

[0020] Furthermore, in order to make the reference voltage generating circuit not need to have two similar circuits, only a single operational amplifier is needed to save chip area and power consumption, it is characterized in that the above-mentioned reference voltage generating circuit also includes: an operational amplifier, whose first input terminal is used to receive the positive reference voltage +VREF; a transistor, whose gate is connected to the output terminal of the operational amplifier, and whose source is connected to the second input terminal of the operational amplifier and the first end of the first resistor string; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output the plurality of different first voltages; a current mirror, which works between the positive voltage VSP and the negative voltage VSN, and the current mirror is connected to the drain of the transistor and the second end of the second resistor string; and the second resistor string, wherein the first end of the second resistor string and the first end of the first resistor string are connected to the ground potential GND, and the second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output the plurality of different second voltages.

[0021] Furthermore, in order to better output the negative voltage, it is characterized in that the above-mentioned current mirror is a current mirror with four transistors.

[0022] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0023] According to an embodiment of the present application, a reference voltage generating circuit is provided, characterized in that it includes: an operational amplifier, a first input terminal of which is used to connect to a ground potential GND; a transistor, a gate of which is connected to the output terminal of the operational amplifier, a source of which is connected to the first end of a first resistor string, and a drain of which is connected to a positive voltage VSP; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages; a second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages, and the first end of the second resistor string and the second end of the first resistor string are connected to the second input terminal of the operational amplifier; and a variable component, wherein the first end of the variable component is connected to the second end of the second resistor string, and the second end of the variable component is connected to a negative voltage VSN, wherein the resistance value of the first resistor string is the same as the resistance value of the second resistor string.

[0024] Furthermore, in order to allow the same current to flow through the first resistor string, the second resistor string and the variable component, it is characterized in that the voltage VP at the first end of the first resistor string is a positive reference voltage +VREF, and the voltage VN at the second end of the second resistor string is a negative reference voltage -VREF, wherein the absolute voltage values ​​of the positive reference voltage +VREF and the negative reference voltage -VREF are the same.

[0025] Furthermore, in order to realize the variable component, it is characterized in that the variable component is one of the following or any combination thereof: a variable resistor; and a current source.

[0026] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0027] According to an embodiment of the present application, a positive and negative voltage source driving circuit is provided, characterized in that it includes: an operational amplifier, whose first input terminal is used to connect to the ground potential GND; a transistor, whose gate is connected to the output terminal of the operational amplifier, whose source is connected to the first end of the first resistor string, and whose drain is connected to the positive voltage VSP; the first resistor string, which includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages to the first multiplexer; a second resistor string, which includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages to the second multiplexer, and the first end of the second resistor string and the second end of the first resistor string are connected to the second input terminal of the operational amplifier; a variable component, The first end of the variable component is connected to the second end of the second resistor string, and the second end of the variable component is connected to the negative voltage VSN, wherein the resistance value of the first resistor string is the same as the resistance value of the second resistor string; the first multiplexer and the second multiplexer, the first multiplexer is used to receive the multiple different first voltages, and select one of the multiple different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, the second multiplexer is used to receive the multiple different second voltages, and select one of the multiple different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier respectively output a positive voltage and a negative voltage to the load circuit.

[0028] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0029] According to an embodiment of the present application, a liquid crystal display is provided, characterized in that it includes: a plurality of liquid crystal units; a plurality of liquid crystal control units for respectively controlling the plurality of liquid crystal units; and a positive and negative voltage source driving circuit, wherein the positive and negative voltage source driving circuit includes: an operational amplifier, a first input terminal of which is used to connect to a ground potential GND; a transistor, a gate of which is connected to an output terminal of the operational amplifier, a source of which is connected to a first end of a first resistor string, and a drain of which is connected to a positive voltage VSP; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages to a first multiplexer; a second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages to the second multiplexer, and the first end of the second resistor string and the second end of the first resistor string are connected to the first end of the operational amplifier; Two input terminals; a variable component, wherein the first terminal of the variable component is connected to the second terminal of the second resistor string, and the second terminal of the variable component is connected to a negative voltage VSN, wherein the resistance value of the first resistor string is the same as the resistance value of the second resistor string; the first multiplexer and the second multiplexer, the first multiplexer is used to receive the multiple different first voltages, and select one of the multiple different first voltages to output a positive voltage reference voltage VREF_VGMP to a positive voltage operational amplifier, the second multiplexer is used to receive the multiple different second voltages, and select one of the multiple different second voltages to output the negative voltage reference voltage VREF_VGMN to a negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier respectively output a positive voltage and a negative voltage to one of the multiple liquid crystal control units, for controlling the grayscale level of one of the multiple liquid crystal units.

[0030] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0031] Due to the adoption of the above scheme, the beneficial effects of the present application are as follows: one of the technical solutions provided by the present application can reduce the use of bandgap reference circuits and operational amplifiers. Another technical solution provided by the present application does not even require the use of a bandgap reference circuit and only requires a single operational amplifier. This can greatly reduce the chip area and reduce a lot of energy consumption during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a block diagram of a positive and negative voltage source driving circuit 100 according to an embodiment of the present application.

[0033] Figure 2 is a block diagram of a positive reference voltage generating circuit 111 and a negative reference voltage generating circuit 112 according to an embodiment of the present application.

[0034] Figure 3 is a block diagram of a positive reference voltage generating circuit 111 and a negative reference voltage generating circuit 112 according to an embodiment of the present application.

[0035] Figure 4 FIG. 4 is a block diagram of a positive reference voltage generating circuit 411 and a negative reference voltage generating circuit 412 according to another embodiment of the present application.

[0036] Figure 5 Based on Figure 4 A block schematic diagram of the illustrated embodiment.

[0037] Figure 6 2 is a block diagram of a reference voltage generating circuit 610 , a first multiplexer 231 , and a second multiplexer 232 according to an embodiment of the present application.

[0038] Figure 7 for Figure 6 A block diagram of a reference voltage generating circuit 610 of the illustrated embodiment is shown.

[0039] Figure 8 for Figure 6 A block diagram of a reference voltage generating circuit 610 of the illustrated embodiment is shown. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] The terms "first", "second", "third", etc. (if any) in the specification and claims of this application and the drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the objects described in these descriptions can be interchanged where appropriate. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware circuits or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0042] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with drawings and specific implementation methods.

[0045] Please refer to Figure 1 As shown, it is a block diagram of a positive and negative voltage source driving circuit 100 according to an embodiment of the present application. The positive and negative voltage generating circuit 100 operates between a positive voltage VSP and a negative voltage VSN. The positive voltage generating part of the positive and negative voltage generating circuit 100 operates between the positive voltage VSP and the ground potential GND. Similarly, the negative voltage generating part of the positive and negative voltage source driving circuit 100 operates between the ground potential GND and the negative voltage VSN. Figure 1 It can be seen that above the ground potential GND is a positive voltage generating part, which generates a positive voltage to the load circuit 130. Below the ground potential GND is a negative voltage generating part, which generates a negative voltage to the load circuit 130.

[0046] In one embodiment, the load circuit 130 may be one or more liquid crystal control units in a liquid crystal display. The liquid crystal control unit may be used to control the grayscale of the liquid crystal unit, thereby controlling the color of the liquid crystal display. It will be appreciated by those skilled in the art that, although the present embodiment uses the liquid crystal control unit of the liquid crystal display as an example of the load circuit 130, the positive and negative voltage source drive circuit 100 provided in the present application is not limited to providing a cross-voltage of the liquid crystal control unit. For example, in addition to the liquid crystal control unit, the thin film transistor (TFT) circuit of the liquid crystal display also requires a negative voltage to turn off the transistor circuit to reduce or avoid leakage current.

[0047] The positive voltage generating part of the positive and negative voltage source driving circuit 100 includes a positive voltage reference voltage generating circuit 111 and a positive voltage operational amplifier (Positive Operational Amplifier) ​​121 in sequence. Similarly, the negative voltage generating part of the positive and negative voltage source driving circuit 100 includes a negative voltage reference voltage generating circuit 112 and a negative voltage operational amplifier 122 (Negative Operational Amplifier) ​​in sequence. The positive voltage operational amplifier 121 generates a voltage between the positive voltage GSP and the ground potential GND. Similarly, the negative voltage operational amplifier generates a voltage between the ground potential GND and the negative voltage GSN. The positive voltage reference voltage generating circuit 111 generates a positive voltage reference voltage VREF_VGMP required by the positive voltage operational amplifier 121. Similarly, the negative voltage reference voltage generating circuit 112 generates a negative voltage reference voltage VREF_VGMN required by the negative voltage operational amplifier 122.

[0048] In the application of small and medium-sized liquid crystal displays, the liquid crystal flip voltage is below 6 volts. Therefore, for the full positive half-voltage liquid crystal panel architecture, the positive voltage VSP is about 5V to 6V, and the negative voltage VSN is about -5V to -6V. Therefore, unlike the application of large-sized liquid crystal displays, when applied to small and medium-sized liquid crystal displays, medium-voltage components (such as 6V) can be used to complete the design of the positive and negative voltage generating circuit 100.

[0049] Please refer to Figure 2 As shown, it is a block diagram of a positive voltage reference voltage generating circuit 111 and a negative voltage reference voltage generating circuit 112 according to an embodiment of the present application. The positive voltage reference voltage generating circuit 111 operates between a positive voltage VSP and a ground potential GND. The positive voltage reference voltage generating circuit 111 includes a first bandgap reference circuit 211, a first reference voltage generating circuit 221, and a first multiplexer 231. The first bandgap reference circuit 211 is used to generate a positive reference voltage +VREF. After receiving the positive reference voltage +VREF, the first reference voltage generating circuit 221 generates a plurality of different first voltages and transmits them to the first multiplexer 231. The first multiplexer 231 selects the required positive voltage reference voltage VREF_VGMP from the above-mentioned plurality of different first voltages.

[0050] The negative voltage reference voltage generating circuit 112 operates between the ground potential GND and the negative voltage VSN. The negative voltage reference voltage generating circuit 112 includes a second bandgap reference circuit 212, a second reference voltage generating circuit 222, and a second multiplexer 232. The second bandgap reference circuit 212 is used to generate a negative reference voltage -VREF. After receiving the negative reference voltage -VREF, the second reference voltage generating circuit 222 generates a plurality of different second voltages and transmits them to the second multiplexer 232. The second multiplexer 232 selects the required negative voltage reference voltage VREF_VGMN from the plurality of different second voltages.

[0051] Those skilled in the art will appreciate that the bandgap reference circuits 211 and 212 are commonly used circuits for generating precise reference voltages, which have excellent temperature stability. The bandgap or energy gap mentioned above refers to the energy gap between the low-energy valence band and the high-energy conduction band of a semiconductor.

[0052] Please refer to Figure 3 , which is a block diagram of a positive reference voltage generating circuit 111 and a negative reference voltage generating circuit 112 according to an embodiment of the present application. Figure 2 The first reference voltage generating circuit 221 may include Figure 3 The first operational amplifier 311 , the first transistor 321 , and the first resistor string 331 are shown. Figure 2 The second reference voltage generating circuit 222 may include Figure 3 The second operational amplifier 312 , the second transistor 322 , and the second resistor string 332 are shown.

[0053] The first input terminal of the first operational amplifier 311 receives the positive reference voltage +VREF from the first bandgap reference circuit 211. The first transistor 321 may be an N-type transistor. Figure 3 In the embodiment of the present invention, the output terminal of the first operational amplifier 311 is connected to the gate of the first transistor 321, which is used to control the on and off of the first transistor 321. The drain of the first transistor 321 is connected to the positive voltage VSP. The source of the first transistor 321 is connected to the second input terminal of the first operational amplifier 311 and the first terminal of the first resistor string 331. The second terminal of the first resistor string 331 is connected to the ground potential GND.

[0054] The first resistor string 331 can include multiple first resistors, and these first resistors can be connected in series. Except that the first end of the first first resistor is connected to the source of the first transistor 321, the first end of each first resistor is connected to the second end of the previous first resistor. Except that the second end of the last first resistor is connected to the ground potential, the second end of each first resistor is connected to the first end of the next first resistor. Multiple lines can be connected to multiple inputs of the first multiplexer 231 respectively at the connection of multiple first resistors. Due to the different number of first resistors passed through, the first voltages of multiple inputs of the first multiplexer 231 are not the same. The first voltage of multiple lines outputted via the first resistor string 331 is between positive voltage VSP and ground potential GND.

[0055] The second input terminal of the second operational amplifier 312 receives the negative reference voltage -VREF from the second bandgap reference circuit 212. The second transistor 322 may be a P-type transistor. Figure 3 In the embodiment of the present invention, the output terminal of the second operational amplifier 312 is connected to the gate of the second transistor 321, which is used to control the on and off of the second transistor 322. The drain of the second transistor 322 is connected to the negative voltage VSN. The source of the second transistor 322 is connected to the first input terminal of the second operational amplifier 312 and the first terminal of the second resistor string 322. The second terminal of the second resistor string 332 is connected to the ground potential GND.

[0056] The second resistor string 332 can include a plurality of second resistors, and these second resistors can be connected in series.Except that the first end of the first second resistor is connected to the source of the second transistor 322, the first end of each second resistor is connected to the second end of the previous first resistor.Except that the second end of the last second resistor is connected to the ground potential, the second end of each second resistor is connected to the first end of the next second resistor.Multiple circuits can be connected to the multiple inputs of the second multiplexer 232 respectively at the junction of multiple second resistors.Due to the different number of the second resistors passed through, the second voltages of the multiple inputs of the second multiplexer 232 are not the same.The second voltage of the multiple circuits outputted via the second resistor string 332 is between the ground potential GND and the negative voltage VSN.

[0057] exist Figure 2 and Figure 3 The embodiment shown includes two bandgap reference circuits 211 and 212 and two reference voltage generating circuits 221 and 222, which are used to generate a positive reference voltage VREF_VGMP and a negative reference voltage VREF_VGMN, respectively. The present application also includes other types of embodiments, which can reduce the number of bandgap reference circuits, further reduce the chip area and power consumption, and increase the competitiveness of the product.

[0058] Please refer to Figure 4 , which is a block diagram of a positive voltage reference voltage generating circuit 411 and a negative voltage reference voltage generating circuit 412 according to another embodiment of the present application. The positive voltage reference voltage generating circuit 411 includes the first bandgap reference circuit 211 and the first multiplexer 231 described previously, and a reference voltage generating circuit 421. The negative voltage reference voltage generating circuit 412 does not include the second bandgap reference circuit 212 described previously, but includes the second multiplexer 232 described previously and a simplified reference voltage generating circuit 422.

[0059] Please refer to Figure 5 As shown, it is based on Figure 4 The positive reference voltage generating circuit 411 includes the first operational amplifier 311, the first transistor 321, and the first resistor string 331 as described above. In addition, Figure 5 The embodiment shown also includes a current mirror structure. The current mirror structure includes four transistors 531-534, which can be composed of Figure 5 The current mirror with four transistors shown is used as a power supply for the negative reference voltage generating circuit 412. It can be understood by those skilled in the art that, in addition to Figure 5 In addition to the four-transistor current mirror shown, there are other types of current mirrors. Figure 5 The embodiment shown.

[0060] When the second input terminal (negative terminal) of the first operational amplifier 331 is connected to the first transistor 321 and the first resistor string 331, negative feedback causes the voltage VP to approach the positive reference voltage +VREF of the first input terminal (positive terminal) of the first operational amplifier 331. Since the voltage VP spans the first resistor string 331, a current I1 is generated. This current I1 provides current to the second resistor string 332 through the aforementioned current mirror structure.

[0061] When the resistances of the first resistor string 331 and the second resistor string 332 are equal, and the currents flowing through the first resistor string 331 and the second resistor string 332 are both currents I1, the voltage VN will be equal to -VP. The negative feedback mentioned above makes VP approach or equal to the positive reference voltage +VREF, and the voltage VN will be equal to -(+VREF), that is, equal to the negative reference voltage -VREF. In other words, the simplified reference voltage generating circuit 422 can include the aforementioned current mirror structure and the second resistor string 332. The description of the second resistor string 332 can refer to the previous embodiment and will not be repeated here.

[0062] Please refer to Figure 6, which is a block diagram of a reference voltage generating circuit 610 and a first multiplexer 231 and a second multiplexer 232 according to an embodiment of the present application. The reference voltage generating circuit 610 does not require any bandgap reference circuit to provide a positive reference voltage +VREF or a negative reference voltage -VREF. Figures 1 to 3 Two bandgap reference circuit embodiments are shown and compared Figure 4 and Figure 5 An embodiment of a single bandgap reference circuit, Figure 6 The reference voltage generating circuit 610 shown can save chip area and energy consumption.

[0063] The reference voltage generating circuit 610 can also generate multiple voltages for the aforementioned first multiplexer 231, for selecting one of them as the positive reference voltage VREF_VGMP. Similarly, the reference voltage generating circuit 610 can generate multiple voltages for the aforementioned second multiplexer 232, for selecting one of them as the negative reference voltage VREF_VGMN.

[0064] Please refer to Figure 7 As shown, it is Figure 6 A block diagram of a reference voltage generating circuit 610 of the illustrated embodiment includes an operational amplifier 710 , a transistor 720 , a first resistor string 731 , a second resistor string 732 , and a variable resistor 740 .

[0065] The first input terminal (positive terminal) of the operational amplifier 710 is connected to the ground potential GND. The output terminal of the operational amplifier 710 is connected to the gate of the transistor 720 for controlling the on and off of the transistor 720. The transistor 720 may be an N-type transistor. Figure 7 In the embodiment of the present invention, the drain of the transistor 720 is connected to the positive voltage VSP. The source of the transistor 720 is connected to the first end of the first resistor string 731. The second input terminal (negative terminal) of the operational amplifier 710 is connected to the second end of the first resistor string 731 and the first end of the second resistor string 732. The second end of the second resistor string 732 is connected to the first end of the variable resistor 740. The second end of the variable resistor 740 is connected to the negative voltage VSN.

[0066] As mentioned above, the first resistor string 731 is formed by a plurality of first resistors connected in series, and the second resistor string is also formed by a plurality of second resistors connected in series. Except that the first end of the first first resistor is connected to the source of the transistor, the first ends of the remaining first resistors are connected to the second end of the previous first resistor. Except that the second end of the last first resistor is connected to the first end of the second resistor string 732 and the second input end (negative end) of the operational amplifier 710, the second ends of the remaining first resistors are connected to the first end of the latter first resistor. Multiple lines can be connected to the multiple inputs of the first multiplexer 231 respectively at the connection of multiple first resistors. Due to the different number of first resistors passed through, the voltages of the multiple inputs of the first multiplexer 231 are not the same. The voltage of the multiple lines outputted by the first resistor string 731 is between the positive voltage VSP and the ground potential GND.

[0067] Except the first end of the first second resistor is connected to the second end of the first resistor string 732 and the second input end (negative end) of the operational amplifier 710, the first ends of the remaining second resistors are connected to the second end of the previous second resistor.Except the second end of the last second resistor is connected to the first end of the variable resistor 740, the second ends of the remaining second resistors are connected to the first end of the latter second resistor.Multiple circuits can be connected to the multiple inputs of the second multiplexer 232 respectively at the connection of multiple second resistors.Due to the different number of second resistors passed through, the voltages of the multiple inputs of the second multiplexer 232 are not the same.The voltage of the multiple circuits outputted via the second resistor string 732 is between ground potential GND and negative voltage VSN.

[0068] Due to the negative feedback of the second end (negative end) of the operational amplifier 710, the voltage at the connection point between the first resistor string 731 and the second resistor string 732 approaches the voltage of the first end (positive end) of the operational amplifier 710, that is, the ground potential GND or 0V. When the resistance value R3 of the variable resistor 740 is adjusted with the negative voltage VSN, the cross voltage between the first end and the second end of the second resistor string 732 is maintained constant. Assume that the resistance value R1 of the first resistor string 731 is the same as the resistance value R2 of the second resistor string 732, and the first resistor string 731, the second resistor string 732 and the variable resistor 740 all flow through the same current I1. Then the resistance value R3 of the variable resistor 740 can be set so that the voltage VP=I1*R1=+VREF, and the voltage VN=I1*R2=-VREF. In this way, a smaller chip area and energy consumption can be used, and the positive reference voltage +VREF and the negative reference voltage -VREF can be obtained at the same time. Then, through the first resistor string 731 , the second resistor string 732 , the first multiplexer 231 , and the second multiplexer 232 , the positive reference voltage VREF_VGMP and the negative reference voltage VREF_VGMN can be obtained.

[0069] Please refer to Figure 8 As shown, it is Figure 6 A block diagram of a reference voltage generating circuit 610 of the illustrated embodiment. Figure 7 Compared with the embodiment shown in FIG. 1 , the variable resistor 740 is changed to a current source 840, and the rest of the components are the same as Figure 7 Remain unchanged. Similarly, the current of the current source 840 can be set so that the voltage VP=I1*R1=+VREF, and the voltage VN=I1*R2=-VREF. In this way, a smaller chip area and energy consumption can be used to obtain the positive reference voltage +VREF and the negative reference voltage -VREF. Then, through the first resistor string 731, the second resistor string 732, the first multiplexer 231 and the second multiplexer 232, the positive voltage reference voltage VREF_VGMP and the negative voltage reference voltage VREF_VGMN can be obtained.

[0070] According to an embodiment of the present application, a reference voltage generating circuit is provided, characterized in that it includes: an operational amplifier, whose first input terminal is used to receive a positive reference voltage +VREF; a transistor, whose gate is connected to the output terminal of the operational amplifier, and whose source is connected to the second input terminal of the operational amplifier and the first end of a first resistor string; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages; a current mirror, operating between a positive voltage VSP and a negative voltage VSN, and the current mirror is connected to the drain of the transistor and the second end of the second resistor string; and the second resistor string, the second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages, wherein the first end of the second resistor string and the second end of the first resistor string are connected to a ground potential GND.

[0071] Furthermore, in order to provide positive voltage and negative voltage simultaneously, it is characterized in that the multiple different first voltages are respectively located between the positive voltage VSP and the ground potential GND, and the multiple different first voltages are respectively located between the ground potential GND and the negative voltage VSN.

[0072] Furthermore, in order to select one from a plurality of positive voltages and a plurality of negative voltages as a positive voltage reference voltage VREF_VGMP and a negative voltage reference voltage VREF_VGMN, it is characterized in that the above-mentioned reference voltage generating circuit also includes a first multiplexer and a second multiplexer, the first multiplexer is used to receive the plurality of different first voltages, and select one from the plurality of different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, the second multiplexer is used to receive the plurality of different second voltages, and select one from the plurality of different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier.

[0073] Furthermore, in order to obtain a temperature-stable reference power supply, it is characterized in that the positive reference voltage +VREF is derived from a bandgap reference circuit, and the bandgap reference circuit operates between the positive voltage VSP and the ground potential GND.

[0074] Furthermore, in order to better output the negative voltage, it is characterized in that the above-mentioned current mirror is a current mirror with four transistors.

[0075] According to an embodiment of the present application, a positive and negative voltage source driving circuit is provided, characterized in that it includes: a bandgap reference circuit, which works between a positive voltage VSP and a ground potential GND, and is used to provide a positive reference voltage +VREF; a reference voltage generating circuit, which is used to receive the positive reference voltage +VREF and output a positive voltage reference voltage VREF_VGMP to a positive voltage operational amplifier and output a negative voltage reference voltage VREF_VGMN to a negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier, which respectively output a positive voltage and a negative voltage to a load circuit.

[0076] Furthermore, in order to select one from a plurality of positive voltages and a plurality of negative voltages as a positive voltage reference voltage VREF_VGMP and a negative voltage reference voltage VREF_VGMN, it is characterized in that the above-mentioned reference voltage generating circuit also includes a first multiplexer and a second multiplexer, and the reference voltage generating circuit is used to receive the positive reference voltage +VREF to generate a plurality of different first voltages and a plurality of different second voltages to the first multiplexer and the second multiplexer respectively, and the first multiplexer selects one from the plurality of different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, and the second multiplexer selects one from the plurality of different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier.

[0077] Furthermore, in order to provide positive voltage and negative voltage simultaneously, it is characterized in that the multiple different first voltages are respectively located between the positive voltage VSP and the ground potential GND, and the multiple different first voltages are respectively located between the ground potential GND and the negative voltage VSN.

[0078] Furthermore, in order to make the reference voltage generating circuit not need to have two similar circuits, only a single operational amplifier is needed to save chip area and power consumption, it is characterized in that the above-mentioned reference voltage generating circuit also includes: an operational amplifier, whose first input terminal is used to receive the positive reference voltage +VREF; a transistor, whose gate is connected to the output terminal of the operational amplifier, and whose source is connected to the second input terminal of the operational amplifier and the first end of the first resistor string; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output the plurality of different first voltages; a current mirror, working between the positive voltage VSP and the negative voltage VSN, the current mirror is connected to the drain of the transistor and the second end of the second resistor string; the first end of the second resistor string and the first end of the first resistor string are connected to the ground potential GND, the second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output the plurality of different second voltages.

[0079] Furthermore, in order to better output the negative voltage, it is characterized in that the above-mentioned current mirror is a current mirror with four transistors.

[0080] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0081] According to an embodiment of the present application, a liquid crystal display is provided, characterized in that it includes: a plurality of liquid crystal units; a plurality of liquid crystal control units respectively controlling the plurality of liquid crystal units; and a positive and negative voltage source driving circuit, wherein the positive and negative voltage source driving circuit includes: a bandgap reference circuit, operating between a positive voltage VSP and a ground potential GND, for providing a positive reference voltage +VREF; a reference voltage generating circuit, for receiving the positive reference voltage +VREF and outputting a positive voltage reference voltage VREF_VGMP to a positive voltage operational amplifier and outputting a negative voltage reference voltage VREF_VGMN to a negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier, respectively outputting a positive voltage and a negative voltage to one of the plurality of liquid crystal control units, for controlling the grayscale level of one of the plurality of liquid crystal units.

[0082] Furthermore, in order to select one from a plurality of positive voltages and a plurality of negative voltages as a positive voltage reference voltage VREF_VGMP and a negative voltage reference voltage VREF_VGMN, it is characterized in that the above-mentioned reference voltage generating circuit also includes a first multiplexer and a second multiplexer, and the reference voltage generating circuit is used to receive the positive reference voltage +VREF to generate a plurality of different first voltages and a plurality of different second voltages to the first multiplexer and the second multiplexer respectively, and the first multiplexer selects one from the plurality of different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, and the second multiplexer selects one from the plurality of different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier.

[0083] Furthermore, in order to make the reference voltage generating circuit not need to have two similar circuits, only a single operational amplifier is needed to save chip area and power consumption, it is characterized in that the above-mentioned reference voltage generating circuit also includes: an operational amplifier, whose first input terminal is used to receive the positive reference voltage +VREF; a transistor, whose gate is connected to the output terminal of the operational amplifier, and whose source is connected to the second input terminal of the operational amplifier and the first end of the first resistor string; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output the plurality of different first voltages; a current mirror, which works between the positive voltage VSP and the negative voltage VSN, and the current mirror is connected to the drain of the transistor and the second end of the second resistor string; and the second resistor string, wherein the first end of the second resistor string and the first end of the first resistor string are connected to the ground potential GND, and the second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output the plurality of different second voltages.

[0084] Furthermore, in order to better output the negative voltage, it is characterized in that the above-mentioned current mirror is a current mirror with four transistors.

[0085] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0086] According to an embodiment of the present application, a reference voltage generating circuit is provided, characterized in that it includes: an operational amplifier, a first input terminal of which is used to connect to a ground potential GND; a transistor, a gate of which is connected to the output terminal of the operational amplifier, a source of which is connected to the first end of a first resistor string, and a drain of which is connected to a positive voltage VSP; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages; a second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages, and the first end of the second resistor string and the second end of the first resistor string are connected to the second input terminal of the operational amplifier; and a variable component, wherein the first end of the variable component is connected to the second end of the second resistor string, and the second end of the variable component is connected to a negative voltage VSN, wherein the resistance value of the first resistor string is the same as the resistance value of the second resistor string.

[0087] Furthermore, in order to allow the same current to flow through the first resistor string, the second resistor string and the variable component, it is characterized in that the voltage VP at the first end of the first resistor string is a positive reference voltage +VREF, and the voltage VN at the second end of the second resistor string is a negative reference voltage -VREF, wherein the absolute voltage values ​​of the positive reference voltage +VREF and the negative reference voltage -VREF are the same.

[0088] Furthermore, in order to realize the variable component, it is characterized in that the variable component is one of the following or any combination thereof: a variable resistor; and a current source.

[0089] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0090] According to an embodiment of the present application, a positive and negative voltage source driving circuit is provided, characterized in that it includes: an operational amplifier, whose first input terminal is used to connect to the ground potential GND; a transistor, whose gate is connected to the output terminal of the operational amplifier, whose source is connected to the first end of the first resistor string, and whose drain is connected to the positive voltage VSP; the first resistor string, which includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages to the first multiplexer; a second resistor string, which includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages to the second multiplexer, and the first end of the second resistor string and the second end of the first resistor string are connected to the second input terminal of the operational amplifier; a variable component, The first end of the variable component is connected to the second end of the second resistor string, and the second end of the variable component is connected to the negative voltage VSN, wherein the resistance value of the first resistor string is the same as the resistance value of the second resistor string; the first multiplexer and the second multiplexer, the first multiplexer is used to receive the multiple different first voltages, and select one of the multiple different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, the second multiplexer is used to receive the multiple different second voltages, and select one of the multiple different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier respectively output a positive voltage and a negative voltage to the load circuit.

[0091] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0092] According to an embodiment of the present application, a liquid crystal display is provided, characterized in that it includes: a plurality of liquid crystal units; a plurality of liquid crystal control units for respectively controlling the plurality of liquid crystal units; and a positive and negative voltage source driving circuit, wherein the positive and negative voltage source driving circuit includes: an operational amplifier, a first input terminal of which is used to connect to a ground potential GND; a transistor, a gate of which is connected to an output terminal of the operational amplifier, a source of which is connected to a first end of a first resistor string, and a drain of which is connected to a positive voltage VSP; the first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages to a first multiplexer; a second resistor string includes a plurality of second resistors connected in series, and the second ends of the plurality of second resistors respectively output a plurality of different second voltages to the second multiplexer, and the first end of the second resistor string and the second end of the first resistor string are connected to the first end of the operational amplifier; Two input terminals; a variable component, wherein the first terminal of the variable component is connected to the second terminal of the second resistor string, and the second terminal of the variable component is connected to a negative voltage VSN, wherein the resistance value of the first resistor string is the same as the resistance value of the second resistor string; the first multiplexer and the second multiplexer, the first multiplexer is used to receive the multiple different first voltages, and select one of the multiple different first voltages to output a positive voltage reference voltage VREF_VGMP to a positive voltage operational amplifier, the second multiplexer is used to receive the multiple different second voltages, and select one of the multiple different second voltages to output the negative voltage reference voltage VREF_VGMN to a negative voltage operational amplifier; and the positive voltage operational amplifier and the negative voltage operational amplifier respectively output a positive voltage and a negative voltage to one of the multiple liquid crystal control units, for controlling the grayscale level of one of the multiple liquid crystal units.

[0093] Furthermore, in order to be applied to small and medium-sized liquid crystal displays, it is characterized in that the positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

[0094] The above is only a preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed in the present application according to the technical solution and application concept of the present application, which should be covered by the protection scope of the present application.

Claims

1. A positive and negative voltage source driving circuit, characterized in that: Include: An operational amplifier, a first input terminal of which is used to connect to a ground potential GND; a transistor, whose gate is connected to the output terminal of the operational amplifier, whose source is connected to the first terminal of the first resistor string, and whose drain is connected to the positive voltage VSP; The first resistor string includes a plurality of first resistors connected in series, and the second ends of the plurality of first resistors respectively output a plurality of different first voltages to the first multiplexer; A second resistor string, comprising a plurality of second resistors connected in series, wherein the second ends of the plurality of second resistors respectively output a plurality of different second voltages to the second multiplexer, and the first end of the second resistor string and the second end of the first resistor string are connected to the second input end of the operational amplifier; A variable component, wherein a first end of the variable component is connected to a second end of the second resistor string, a second end of the variable component is connected to a negative voltage VSN, and a resistance value of the first resistor string is the same as a resistance value of the second resistor string; The first multiplexer and the second multiplexer, the first multiplexer is used to receive the multiple different first voltages, and select one of the multiple different first voltages to output the positive voltage reference voltage VREF_VGMP to the positive voltage operational amplifier, and the second multiplexer is used to receive the multiple different second voltages, and select one of the multiple different second voltages to output the negative voltage reference voltage VREF_VGMN to the negative voltage operational amplifier; and The positive voltage operational amplifier and the negative voltage operational amplifier respectively output a positive voltage and a negative voltage to a load circuit.

2. The positive and negative voltage source driving circuit according to claim 1, characterized in that: The positive voltage VSP is between 5V and 6V, and the negative voltage VSN is between -5V and -6V.

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