TW509886B - Operational amplifier for driving integrated circuit of liquid crystal display - Google Patents

Abstract

The present invention provides an operational amplifier comprising an input stage circuit for receiving an input signal and a driving stage circuit for coupling to one output terminal of the input stage circuit. The driving stage circuit is used to provide a current to a loading. According a voltage from the output signal of the driving stage circuit, a feedback compensation means is for selecting one of the feedback compensation circuits as the feedback compensation path for the driving stage circuit. Furthermore, a circuit-controlling circuit controls the bias voltage of the driving stage circuit according the input signal of the input stage circuit and the output signal of the driving stage circuit. When the input signal is much than the output signal, a current provided by a power supply flows into the loading in the driving stage circuit. When the input signal is less than the output signal, a current flows from the loading to ground through the driving stage circuit. When the input signal is equal to the output signal, there is no current to the loading. The present invention provides the current-controlling circuit and the feedback compensation means for reducing the space of the operational amplifier and the consumption of the electric power.

Description

509886 V. Description of the invention (i) 5-1 Field of invention: The present invention relates to operational amplifiers, and more particularly to operational amplifiers applied to liquid crystal display driving integrated circuits. 5-2 Background of the Invention: The first figure shows a schematic block diagram of a conventional operational amplifier. A traditional differential operational amplifier 150 includes an input stage 110, a driving stage 120, and a compensation network 140. The input stage 110 includes several MOS transistors, which mainly receive an input voltage with a high input impedance and a large range of variation, such as voltage signals from logic circuits after digital / analog conversion; the drive stage 1 2 0 also includes A number of M0S transistors, after receiving the voltage from the input stage 110, provide sufficient output current to a load capacitor 130, which then converts the current into the required output voltage value. The feedback compensation 14 0 is used to adjust the input terminal of the boost stage 120 and the stabilization circuit. Generally, it includes a compensation capacitor made of polycrystalline silicon or metal. The second figure shows the intention of applying the differential operational amplifier 150 of the first figure to a part of the wiring in the liquid crystal display driver integrated circuit. The differential op amp 1 50 receives the input voltage from the digital / analog conversion,

5 ^ p6 μ " Explanation (2) The wiring method of the follower (νο 11 age f ο 1 1 ower) provides a buffer (bu ff er), outputting an output current equal to the input voltage value to a liquid crystal display, etc. Effective load capacitance 1 6 0. However, due to the large capacitive load required for the equivalent load capacitance of a liquid crystal display (75 pF to 100 pF), sufficient output current is required; if a conventional bipolar operational amplifier is used to complete it, the driver stage is 120 The M0S transistor must use a larger area in order to provide sufficient current to the equivalent load capacitance 160 of the liquid crystal display. On the other hand, the compensation capacitor of the feedback compensation 140 in the differential operational amplifier 150 must take a larger value in order for the two-pole operational amplifier to operate stably within the operating voltage operating range. Therefore, the application of traditional operational amplifiers in liquid crystal display driving integrated circuits will cause the disadvantage of occupying a larger area; in addition, larger area M0S transistors will cause a larger static current, which will cause the liquid crystal display driving integrated circuits. Disadvantages of power consumption. At present, most of the methods for solving power consumption start with improving a single component, driving stage or feedback compensation; however, because there are several characteristics between the driving stage and the return compensation, it is impossible to improve the driving stage or The feedback compensation achieves the purpose of saving power (the quiescent current is 10 ~ 20 u A) and saving area. Spring 5-3 Purpose and Summary of Invention:

Page 7 509886 V. Description of the invention (3) In view of the above background of the invention, the present invention mainly provides an operational amplifier. The operational amplifier uses a current controller to improve the driving stage, while achieving the purpose of providing sufficient current and saving area. . Another object of the present invention is to provide an operational amplifier. The operational amplifier can improve the feedback compensation by an adaptive feedback compensation, can stably operate within the operating electric operating range, and achieve the purpose of saving area. According to the above-mentioned object, the present invention provides an operational amplifier for an integrated circuit for driving a liquid crystal display, which includes: an input stage circuit for receiving an input signal; and a driver stage circuit connected to the input stage circuit. An output terminal for supplying a current to a load; a feedback compensation device which decides to select one of the plurality of feedback compensation circuits as the feedback of the driver circuit according to the voltage of an output signal of one of the driver circuits Compensation path; a current control circuit that controls the bias voltage of the booster circuit according to the input signal of the input stage circuit and the output signal of the booster circuit, wherein when the input signal is greater than the output signal, the booster circuit provides a current from a power source to Load; when the input signal is less than the output signal, current flows from the load to the ground via the booster circuit; and when the input signal is equal to the output signal, the booster circuit does not provide current to the load. The operation of the current control circuit and the feedback compensation device can make the operational amplifier achieve the purpose of small area and power saving.

509886 V. Description of the invention (4) 5-4 Detailed description of the invention: When the present invention is described in detail by the following examples, persons familiar with this field should have the knowledge that the present invention does not depart from the scope of the proposed patent, Allows for several amendments and replacements. The structure used for the disclosure is not limited to a specific purpose operational amplifier, but the diagram is also used to illustrate the preferred embodiment, not to limit the scope of the present invention. The main object of the present invention is to provide an operational amplifier for an integrated circuit for driving a liquid crystal display, which includes: an input stage device for receiving a first input signal and outputting a first output signal; a driving stage device for Receiving a first output signal and outputting a second output signal, the driving device includes a plurality of first metal oxide semiconductor transistors; a current control device receives a first input signal and a second output signal and outputs a plurality of third output signals . These third output signals are used to control the first metal oxide semiconductor transistor, so that one of the first metal oxide semiconductor transistors outputs a second output signal. The current control device includes: a voltage comparator receiving a first input signal and a second output signal; the voltage comparator outputs two comparator outputs connected to a plurality of gate terminals of the first metal oxide semiconductor transistor; and a resistor It has two endpoints, one of the two ends, connected to a first current source via one of the two comparator outputs; the other of the two ends, connected to the first one through the other of the two comparator outputs Two current sources. In addition, it also includes an adaptive (a d a p t i v e) feedback compensation device that is connected to the first output signal and the second output signal. The adaptive (a d a p t i v e) feedback compensation device includes a potential comparator to compare the first

Page 9 509886 V. Description of the invention (5) Two output signals and a reference voltage; a second metal oxide semiconductor transistor is connected to the second output signal. When the second output signal is greater than the reference voltage, the second metal oxide semiconductor The transistor can be connected to the first output signal; and a third metal oxide semiconductor transistor is connected to the second output signal. When the second output signal is less than the reference voltage, the third metal oxide semiconductor transistor can be connected to the first output signal. The output signals are connected. The operation of the current device and adaptive feedback compensation can make the operational amplifier achieve the purpose of small area and power saving. Embodiments of the present invention will be described with reference to the third to fifth figures. The third figure is a block diagram according to the present invention, for explaining an operational amplifier applied to a liquid crystal display driving integrated circuit. The operational amplifier 50 of the present invention includes an input stage device 10, a push stage device 20, an adaptive (a d a p t i v e) feedback compensation 40, a current controller 60, and a load capacitor 30. The input stage device 10 includes a number of MOS transistors, which mainly receive an input voltage with a high input impedance and a large range of variation, such as voltage signals from logic circuits after digital / analog conversion; the drive stage device 20 also includes several The MOS transistor mainly receives a voltage from the input stage device 10 and provides sufficient output current to a load capacitor 30, which then converts the current into a desired output voltage value. One of the keys of the present invention is adaptive compensation (a d a p t i v e) feedback compensation 40, which aims at reducing the area occupied by the capacitor and enabling the operational amplifier 50 to operate stably within the operating voltage operating range. Refer to the fourth figure for a schematic diagram of the main components of the adaptive feedback compensation 40, including the first MOS compensation.

Page 10 509886 V. Description of the invention (6) A compensation capacitor 70, a second MOS compensation capacitor 71 and a potential comparator 72. In this embodiment, the conventional compensation capacitor is replaced with a MOS compensation capacitor. Traditional compensation capacitors are mostly made of polycrystalline silicon or metal, which has a high manufacturing cost and takes up a large area. For the production of one layer of polycrystalline silicon and two metal layers in the same level of CMOS process, the manufacturing cost of M0S compensation capacitors is low. And a large area can be saved; in this embodiment, the area occupied by the M0S compensation capacitor is only 1/100 of the metal compensation capacitor. Therefore, the M0S compensation capacitor in the present invention can save the capacitor area of the feedback compensation. The potential comparator 72 is used to receive the output voltage of the driving stage and a reference voltage. After comparing the two, its output is used to control the input stage output voltage line to select one of the M0S compensation capacitors as the working compensation capacitor. In this embodiment, when the output voltage of the driving stage is greater than the reference voltage, the output of the potential comparator 72 can control a selection circuit (not shown in the figure) to make the control input stage output voltage line select the first M0S compensation capacitor 70 As a compensation capacitor in operation. On the other hand, when the output voltage of the driving stage is less than the reference voltage, the output of the potential comparator 72 can control the output voltage line of the input stage by controlling a selection circuit to select the second MOS compensation capacitor 71 as the working compensation capacitor. That is, the first MOS compensation capacitor 70 in this embodiment is suitable for operation in a range where the voltage is higher than the reference voltage, and the second MOS compensation capacitor 71 is suitable for operation in a range where the voltage _ is lower than the reference voltage. Furthermore, the capacitance value of the first M0S compensation capacitor 70 or the second M0S compensation capacitor 71 can be determined by the output voltage of the input stage and the boost stage, so that the operational amplifier can stably operate within the operating voltage operating range.

JU ^ OOO JU ^ OOO V. Description of the Invention (7) In order to make ί 的, the other-key of the present invention is current control "ο, the purpose is to make the operational amplifier 50 in the static state of the eight functions ...-the purpose is Operation: to achieve power saving n ± and even different amplifiers 50 0 to work fine! You can change the bias of the M0S transistor in the drive stage, so that the drive can provide enough capacitance to Push the capacitive load 30. The main components of the push display and controller 60 are connected to the push-level device. The main components of the current control are 60. The main components include a voltage comparator 80, an electricity source, a second current source 82, and a resistor 83. The main drive of the two 20: including the first MOS transistor 84 and the second MOS transistor 85. In this embodiment, the two input control terminals of the voltage comparator 80 are connected to the input stage and the input stage respectively. The output of the stage 20 is pushed. The two output terminals of the voltage comparator 80 are separately connected to the gate control terminals of the first MOS transistor 84 and the second MOS transistor 85. Furthermore, the first current source 81 One end is connected to the supply voltage VDD, and the other end is connected to one end of the resistor 83 via the a 'point; the second One end of the current source 82 is grounded, and the other end is connected to the other end of the resistor 8 3 through the n b11 point. On the other hand, the first M0S transistor 84 is a PM0S transistor whose drain terminal is connected to the supply voltage VDD. The extreme terminal is connected to the negative terminal of the second M0S transistor 85 which is nmos through the "c" point, and the source terminal of the second M0S transistor 85 is ground. When the operational amplifier 50 is in an operating state, when Input stage device i 〇509886 V. Description of the invention (8) When the input of the (8) is greater than the output of the drive stage device 20, several currents will flow into the voltage comparator 80 from the two output terminals of the voltage comparator 80 respectively, so ff aπ The voltage between the point and π 1) ′ point will drop, so that the first MOS transistor 84 of the driving stage device 20 can provide sufficient current to drive the capacitive load 30 through the “cn” point. Conversely, when the input of the input stage device 10 is smaller than the output of the push stage 20, some currents will flow out of the voltage comparator 80 from the two output terminals of the voltage comparator 80 respectively. Will rise, so that the second M0S transistor 85 of the driving stage device 20 can provide sufficient current to drive the capacitive load 30 through the n c " point. Therefore, one of the keys of the present invention is that the operational amplifier 50 is in an operating state When the bias voltage of the first M0S transistor __ 84 and the second M0S transistor 85 of the driving stage device 20 is dynamically changed, the driving stage device 20 can provide sufficient current to drive the capacitive load 30 to overcome the large area M0S One of the key points of the present invention is that when the operational amplifier 50 is in a static state, the input of the input stage 10 is equal to the output of the driving stage device 20, and a current passes through the first current source 81. An point flows to the resistance 83, and then is grounded to the second current source 82 through the ff bn point, so that the voltage at the point n an is approximately the supply voltage VDD, and the voltage at the point n bn is approximately grounded. One M0S Neither the crystal 84 nor the second M0S transistor 85 provides current to the capacitor load 30; in this way, the operational amplifier of the present invention can achieve the function of saving power. The above description is only a preferred embodiment of the present invention, and is not To

Page 13 509886

Page 509886 shows the schematic diagram of the first block diagram of the traditional differential operational amplifier circuit diagram; the second diagram shows the circuit connection schematic diagram of the traditional differential operational amplifier applied to the liquid crystal display drive integrated circuit; the third diagram is the present invention A block diagram of a circuit block of an operational amplifier; a fourth diagram is a circuit diagram of some main components of the operational amplifier of the present invention; and a fifth diagram is a circuit diagram of other main components of the operational amplifier of the present invention. Symbols of the main parts: 10 Tm Step-up device 20 Push-level device 30 Capacitive load 40 Adaptive feedback compensation 50 Operational amplifier 6 0 Current controller 70 No. MOS compensation capacitor 71 No. — MOS compensation capacitor 72 Potential comparator 80 Voltage comparison Device

Page 509886 Brief description of the diagram 81 The first current source 82 The first current source 83 Resistor 84 First MOS transistor 85 Second MOS transistor 110 Input stage 120 Push stage 130 Capacitive load 140 Feedback compensation 150 Differential operational amplifier 160 Liquid crystal display Equivalent load capacitance

Page 16

Claims (1)

509886 VI. Application for patent scope 1. An operational amplifier including an input stage circuit for receiving an input signal; a driver stage circuit connected to an output terminal of the input stage circuit for supplying a current to a A load; a feedback compensation device that decides to select one of the plurality of feedback compensation circuits as a feedback compensation path of the drive stage circuit according to the voltage level of an output signal of the drive stage circuit; a current control circuit that According to the input signal of the input stage circuit and the output signal of the drive stage circuit to control the bias voltage of the drive stage circuit, so that when the input signal is greater than the output signal, the drive stage circuit is provided with a current To the load; when the input signal is less than the output signal, current flows from the load to the ground via the driving stage circuit; and when the input signal is equal to the output signal, the driving stage circuit does not provide current to the load. 2. For example, the operational amplifier of the scope of patent application, wherein the above-mentioned feedback compensation device includes a comparator, which compares the output signal of the driving stage circuit with a reference voltage to select a plurality of the feedback compensation. The circuit of _ of-° 3. If the operational amplifier of the second patent application range, wherein the above-mentioned feedback compensation device includes a switch, the switch is controlled by an output of the comparator, Page 17 509886 VI. Scope of patent application Used to connect one input terminal of the driver circuit to the selected feedback compensation circuit. 4. The operational amplifier according to item 1 of the patent application range, wherein the current control circuit includes a comparator that compares the input signal of the input stage circuit with the output signal of the boost stage circuit to generate the bias voltage to the boost Level circuit. 5. An operational amplifier comprising: an input stage device for receiving a first input signal and outputting a first image output signal; a drive stage device for receiving the first output signal and outputting a second output signal; and An adaptive feedback compensation device is connected to the first output signal and the second output signal. The adaptive feedback compensation device includes: a plurality of metal oxide semiconductor transistors and the second output signal Phase connection; and a potential comparator for selecting one of the metal oxide semiconductor transistors to connect the metal oxide semiconductor transistor to the first output signal. _ 6. The operational amplifier according to item 5 of the patent application scope, further comprising a capacitive load for receiving the second output signal. Page 18 509886 6. Application scope of patent 7. If the operational amplifier of scope 5 of the patent application, the above-mentioned potential comparator compares the second output signal with a reference voltage and outputs a comparison signal to select the metal oxide The semiconductor transistor acts as a compensation capacitor. 8. An operational amplifier applied to an integrated circuit for driving a liquid crystal display, the operational amplifier includes: an input stage device for receiving a first input signal and outputting a first output signal; a driving stage device for receiving The first output signal and a second output signal; and a adaptive feedback compensation device connected to the first output signal and the second output signal, the adaptive feedback compensation The device comprises: a potential comparator for comparing the second output signal with a reference voltage; a first metal oxide semiconductor transistor is connected with the second output signal; when the second output signal is greater than the reference voltage, the first A metal oxide semiconductor transistor may be connected to the first output signal; and a second metal oxide semiconductor transistor may be connected to the second output signal. When the second output signal is less than the reference voltage, the second metal The oxyhalogen conductor can be connected to the first output signal. 9. The operational amplifier according to item 8 of the patent application, further comprising a capacitive load for receiving the second output signal. Page 19 509886 VI. Application scope of patent 10. For the operational amplifier of the scope of patent application No. 8, wherein the first metal oxide semiconductor transistor is connected to the first output signal, it is used as a compensation capacitor. 1 1. The operational amplifier according to item 8 of the scope of patent application, wherein the second metal-oxide semiconductor transistor is used as a compensation capacitor when it is connected to the first output signal. 1 2. An operational amplifier includes: _ an input stage device for receiving a first input signal and outputting a first output signal; a driving stage device for receiving the first output signal and outputting a second output signal, The driving device includes a plurality of metal-oxide semiconductor transistors; and a current control device receives the first input signal and the second output signal and outputs a plurality of third output signals, and the third output signals are used to control the A metal oxide semiconductor that causes one of the metal oxide semiconductors to output the second output signal. The current control device includes: a voltage comparator receives the first input signal and the second output_ signal, and the voltage comparator outputs two A comparator output connected to a plurality of gate terminals of the metal-oxide-semiconductor; and a resistor having two ends, one of the two ends, being connected to a first current source through one of the two comparator outputs, The other end of the two ends Page 20 509886 6. The scope of patent application. The other output of the two comparators is connected to a second current source. 1 3 · The operational amplifier according to item 12 of the patent application scope further includes a capacitive load for receiving the second output signal. 14. The operational amplifier according to item 12 of the scope of patent application, wherein the metal-oxide semiconductor includes two metal-oxide semiconductors of opposite conductivity. 15. The operational amplifier according to item 12 of the patent application scope, wherein the first current source further includes a supply voltage. φ 1 6. The operational amplifier according to item 12 of the patent application range, wherein the second current source further includes a connection to ground. 1 7. An operational amplifier applied to an integrated circuit for driving a liquid crystal display, the operational amplifier includes: an input stage device for receiving a first input signal and outputting a first output signal; a driving stage device for receiving The first output signal and a second output signal. The driving device includes: a first conductive metal oxide semiconductor transistor, which can output the second output signal through an output terminal; and a first A second metal-oxide-semiconductor transistor of one of two conductivity types, which can output the second output signal through the output terminal; and Page 21 509886 VI. Patent application scope A current control device receives the first input signal and the second output signal. The current control device includes: a voltage comparator receives the first input signal and the second output signal, and has The two comparator output terminals are respectively connected to the gate of the first metal oxide semiconductor transistor and the gate of the second metal oxide semiconductor transistor; and a resistor has a first terminal and a second terminal, wherein The first terminal can be connected to one of the two comparator output terminals, the gate of the first metal oxide semiconductor transistor and a first current source, and the second terminal can be connected to the two comparator outputs. At the other end, the gate of the second metal-oxide-semiconductor transistor and a second current source. 18. The operational amplifier according to item 17 of the patent application scope, further comprising a capacitive load for receiving the second output signal. 19. The operational amplifier according to item 17 of the scope of patent application, wherein when the first input signal is greater than the second output signal, a current flows in from the output ends of the two comparators to make the first gold The oxygen semiconductor transistor outputs the second output signal through the output terminal. 2 0. The operational amplifier according to item 19 of the scope of patent application, wherein the first metal oxide semiconductor transistor is a P-type metal oxide semiconductor transistor. 2 1. The operational amplifier according to item 17 of the scope of patent application, wherein the voltage comparator described above, when the first input signal is smaller than the second output signal, Page 22 509886 VI. Scope of patent application Two comparators output currents, so that the second metal-oxide-semiconductor transistor outputs the second output signal through the output terminal. 2 2. The operational amplifier according to item 21 of the patent application range, wherein the second metal-oxide semiconductor transistor is an N-type metal-oxide semiconductor transistor. 2 3. The operational amplifier according to item 17 of the patent application, wherein the first current source further includes a supply voltage. 2 4. The operational amplifier according to item 23 of the patent application range, wherein the second φ current source further includes a connection to ground. When the first input signal is equal to the second output signal, the voltage at the first terminal Is approximately equal to the supply voltage, and the second terminal is approximately equal to ground, so that the second output signal has no current. 2 5. An operational amplifier applied to an integrated circuit for driving a liquid crystal display, the operational amplifier includes: an input stage device for receiving a first input signal and outputting a first output signal; a driving stage device for receiving The first output signal and a second output signal are output, and the driving device includes a plurality of first metal oxide semiconductor transistors; a current control device receives the first input signal and the second output signal and outputs a plurality of A third output signal, the third output signals are used to control the first metal oxide semiconductor transistors, Page 23 509886 VI. One of the patent-application crystals outputs the second output signal. The current control device includes: a voltage comparator receives the first input signal and the second output signal, and the voltage comparator outputs two comparisons. A resistor output connected to the plurality of gate terminals of the first metal-oxide-semiconductor transistor; and a resistor having two terminals, one of the two terminals, connected to a first via one of the two comparator outputs A current source, the other of the two ends, being connected to a second current source via the other of the two comparator outputs; and an adaptive feedback compensation device, the first output signal, and the second The output signal is connected. The adaptive feedback compensation device includes: __ a potential comparator to compare the second output signal with a reference voltage; a second metal-oxide-semiconductor transistor and the second output signal Connected, when the second output signal is greater than the reference voltage, the second metal oxide semiconductor transistor may be connected to the first output signal; and a third metal oxide semiconductor Crystal and the second output signal is connected to ground, when the second output signal is less than the reference voltage, the third metal-oxide-semiconductor transistor may be connected to the first output signal. 26. The operational amplifier according to item 25 of the patent application scope, further comprising a capacitive load for receiving the second output signal. 2 7. The operational amplifier according to item 25 of the scope of patent application, wherein when the second metal-oxide semiconductor transistor is connected to the first output signal, it is used for Page 24 · 509886 6. The scope of patent application is a compensation capacitor. 2 8 · The operational amplifier according to item 25 of the patent application range, wherein the second metal-oxide semiconductor transistor is used as a compensation capacitor when it is connected to the first output signal. 29. The operational amplifier according to item 25 of the patent application range, wherein the first gold-oxide semiconductor transistor includes two kinds of first gold-oxide semiconductor transistors of opposite conductivity. 30. The operational amplifier of claim 25, wherein the first current source further includes a supply voltage. 3 1. The operational amplifier according to item 2.25 of the patent application range, wherein the second current source further includes a connection to ground. 32. If the operational amplifier of the 25th item of the patent application range, wherein the two comparator outputs described above are two currents flowing into the voltage comparator when the first input signal is greater than the second output signal, the resistance of The voltage at these two ends drops. 3 3. If the operational amplifier of the 25th item of the patent application range, wherein the two comparator outputs mentioned above, when the first input signal is smaller than the second output signal, are two currents flowing out of the voltage comparator, so that the resistance of Voltage at the two ends Page 509886 Page 26