CN102142820B - Dual Channel Operational Amplifier Circuit - Google Patents

Abstract

The invention relates to a dual-channel operational amplifier circuit. The dual-channel operational amplifier circuit comprises a first operational amplifier and a second operational amplifier. The second operational amplifier and the first operational amplifier are operated in a half-voltage operation mode. In a first frame period, the operating voltage range of the first input stage, the first gain stage and the first output stage is switched to be between a working voltage and a half working voltage by the dual-channel operational amplifier, and the operating voltage range of the second input stage, the second gain stage and the second output stage is switched to be between the half working voltage and a ground voltage. In a second frame period, the dual-channel operational amplifier switches the operating voltage range of the second input stage and the second gain stage between the working voltage and the half-working voltage, and switches the operating voltage range of the first input stage and the first gain stage between the half-working voltage and the ground voltage.

Description

Dual Channel Operational Amplifier Circuit

technical field

The invention relates to a dual-channel operational amplifier circuit, and in particular to a dual-channel operational amplifier circuit with low power consumption and avoiding abnormal display.

Background technique

Operational amplifiers in conventional source drivers can be classified as operating in a half-voltage operation mode or a full-voltage operation mode. Please refer to FIG. 1 , which shows a schematic diagram of a conventional operational amplifier circuit in a half-voltage operation mode. Based on the polarity switching requirements of the liquid crystal display, the operational amplifier circuit 100 needs to output data with different polarities to the nodes N1 and N2 during different frame periods. In a first frame period FP1, the positive polarity data PS is output to the node N1 through a first input stage 112, a first gain stage 114 and a first output stage 116, and the negative polarity data NS is passed through a second input stage 122, A second gain stage 124 and a second output stage 126 output to the node N2.

In a second frame period FP2, the positive polarity data PS is output to the node N2 through the first input stage 112, the first gain stage 114 and the first output stage 116, and the negative polarity data NS is passed through the second input stage 122, the second gain stage 124 and the second output stage 126 output to the node N1. However, for a single node, positive polarity data and negative polarity data are respectively processed through different input stages and gain stages, resulting in different voltage offsets. In this way, an error will be generated when the polarity is switched, causing the liquid crystal display to flicker, and an additional compensation mechanism is required to solve the problem.

Please refer to FIG. 2 , which shows a schematic diagram of a conventional operational amplifier circuit in full-voltage operation mode. Based on the polarity conversion requirement of the liquid crystal display, the operational amplifier circuit 200 needs to output data with different polarities to the nodes N1 and N2 during different frame periods. In the first frame period FP1, the positive polarity data PS is output to the node N1 through a first input stage 212, a first gain stage 214 and a first output stage 216, and the negative polarity data NS is passed through a second input stage 222, a The second gain stage 224 and a second output stage 226 output to the node N2.

In the second frame period FP2, the positive polarity data PS is output to the node N2 through the second input stage 222, the second gain stage 224 and the first output stage 216, and the negative polarity data NS is passed through the first input stage 212, the first gain stage 214 And the second output stage 226 outputs to the node N1. In this way, for a single node, positive polarity data and negative polarity data are respectively processed through the same input stage and gain stage, so the problem of voltage offset will not occur. However, due to full-voltage operation, the first output stage 212 and the second output stage 222 cannot share current, and the first gain stage 214 and the second gain stage 224 cannot share current, which will result in large current consumption.

Contents of the invention

The object of the present invention is to provide a dual-channel operational amplifier circuit. By making the data of different polarities of a single output node be processed by the same input stage and gain stage, it is possible to avoid the problem of abnormal display, and by switching the switch to enable dual The channel operational amplifier circuit operates in the half-voltage operation mode, so the current consumption can be saved.

According to a first aspect of the present invention, a dual-channel operational amplifier circuit is provided, including a first operational amplifier and a second operational amplifier. The first operational amplifier has a first input stage, a first gain stage and a first output stage. The second operational amplifier has a second input stage, a second gain stage and a second output stage. The second operational amplifier and the first operational amplifier operate in a half-voltage operation mode. Wherein, in a first frame period, the operating voltage range of the dual-channel operational amplifier switches the first input stage, the first gain stage, and the first output stage to be between a working voltage and a half working voltage, so that a positive polarity signal passes through the first An input stage, a first gain stage and a first output stage are output to a first node, and the operating voltage range of the second input stage, the second gain stage and the second output stage is switched from a half working voltage to a dual-channel operational amplifier Between the ground voltage, a negative polarity signal is output to a second node through the second input stage, the second gain stage and the second output stage. Wherein, in a second frame period, the operating voltage range of the dual-channel operational amplifier switches the second input stage, the second gain stage, and the first output stage to be between the operating voltage and the half operating voltage, so that the positive polarity signal passes through the second input stage, the second gain stage and the first output stage are output to the second node, and the operating voltage range of the dual-channel operational amplifier switching first input stage, the first gain stage and the second output stage is between the half operating voltage and the ground voltage , so that the negative polarity signal is output to the first node through the first input stage, the first gain stage and the second output stage.

Description of drawings

In order to make the above content of the present invention more obvious and understandable, preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a schematic diagram of a conventional operational amplifier circuit in a half-voltage operation mode.

FIG. 2 is a schematic diagram of a conventional operational amplifier circuit in full-voltage operation mode.

FIG. 3 is a schematic diagram of a dual-channel operational amplifier circuit according to a preferred embodiment of the present invention.

4A and 4B are circuit diagrams of a dual-channel operational amplifier circuit according to a preferred embodiment of the present invention.

Detailed ways

The present invention proposes a dual-channel operational amplifier circuit. By making the data of different polarities of a single output node be processed by the same input stage and gain stage, the problem of abnormal display can be avoided, and the dual-channel operation can be achieved by switching the switch. The amplifier circuit operates in the half-voltage operation mode, so the current consumption can be saved.

Please refer to FIG. 3 , which shows a schematic diagram of a dual-channel operational amplifier circuit according to a preferred embodiment of the present invention. The dual-channel operational amplifier circuit 300 includes a first operational amplifier and a second operational amplifier. The first operational amplifier has a first input stage 312 , a first gain stage 314 and a first output stage 316 . The second operational amplifier has a second input stage 322 , a second gain stage 324 and a second output stage 326 . The dual-channel operational amplifier circuit 300 enables the second operational amplifier and the first operational amplifier to operate in a half voltage operation mode.

The dual-channel operational amplifier circuit 300 is, for example, applied in a source driver of a liquid crystal display. Based on the polarity conversion requirement of the liquid crystal display, the operational amplifier circuit 300 needs to output data with different polarities to the nodes N1 and N2 during different frame periods.

In a first frame period FP1, the dual-channel operational amplifier 300 switches the operating voltage range of the first input stage 312, the first gain stage 314 and the first output stage 316 to be between an operating voltage VDD and half of the operating voltage VDD/2, A positive polarity signal PS is output to the node N1 through the first input stage 312 , the first gain stage 314 and the first output stage 316 . At the same time, the operating voltage range of the dual-channel operational amplifier 300 switches the second input stage 322, the second gain stage 324 and the second output stage 326 is between the half operating voltage VDD/2 and a ground voltage GND, so that a negative polarity signal NS Output to the node N2 through the second input stage 322 , the second gain stage 324 and the second output stage 326 .

After that, in a second frame period FP2, the dual-channel operational amplifier 300 switches the operating voltage range of the second input stage 322, the second gain stage 324 and the first output stage 316 to be between the working voltage VDD and the half working voltage VDD/2 , so that the positive polarity signal PS is output to the node N2 through the second input stage 322 , the second gain stage 324 and the first output stage 316 . In this way, the negative polarity signal NS and the positive polarity signal PS of the node N2 are processed by the same second input stage 322 and the second gain stage 324 so that there is no problem of voltage offset, and both are processed by the same polarity output stage output.

At the same time, in the second frame period FP2, the dual-channel operational amplifier 300 also switches the operating voltage range of the first input stage 312, the first gain stage 314, and the second output stage 326 to be between the half operating voltage VDD/2 and the ground voltage GND. , so that the negative polarity signal NS is output to the node N1 through the first input stage 312 , the first gain stage 314 and the second output stage 326 . In this way, both the positive polarity signal PS and the negative polarity signal NS of the node N1 are processed by the same first input stage 312 and the first gain stage 314 without the problem of voltage offset, and both are processed by the same polarity output stage output.

In addition, since the first input stage 312 and the second input stage 322 are in the half-voltage operation mode, they can share current. Similarly, the first gain stage 314 and the second gain stage 324 are in the half-voltage operation mode, so both can share current; the first output stage 316 and the second output stage 326 are in the half-voltage operation mode, so both Current sharing is also possible. In this way, the dual-channel operational amplifier 300 of the present invention can save current consumption.

Please refer to FIG. 4A and FIG. 4B , which illustrate a circuit diagram of a dual-channel operational amplifier circuit according to a preferred embodiment of the present invention. In FIG. 4A and FIG. 4B , the dual-channel operational amplifier circuit 300 further includes a plurality of first switches φ1 , a plurality of second switches φ2 , a plurality of third switches φ3 and a plurality of fourth switches φ4 . The dual-channel operational amplifier circuit 300 essentially switches the first input stage 312, the first gain stage 314, the first output stage 316, the second input stage 322, the second gain stage 324 and the The operating voltage range of the second output stage 326 .

In the first frame period FP1, the plurality of first switches φ1 are turned on and the plurality of second switches φ2 are turned off, so that the operating voltage range of the first input stage 312, the first gain stage 314, and the first output stage 316 is the operating voltage VDD The operating voltage range of the second input stage 322 , the second gain stage 324 and the second output stage 326 is between the half operating voltage VDD/2 and the ground voltage GND. Meanwhile, the plurality of third switches φ3 are turned on and the plurality of fourth switches φ4 are turned off, so that the first output stage 316 is coupled to the node N1, and the second output stage 326 is coupled to the node N2.

Wherein, in the second frame period FP2, the plurality of first switches φ1 are turned off and the plurality of second switches φ2 are turned on, so that the operating voltage ranges of the second input stage 322, the second gain stage 324 and the first output stage 316 are working The voltage VDD is between the half working voltage VDD/2, and the operating voltage range of the first input stage 312, the first gain stage 314, and the second output stage 326 is between the half working voltage VDD/2 and the ground voltage GND. The third switch φ3 is turned off and the fourth switches φ4 are turned on, so that the first output stage 316 is coupled to the node N2, and the second output stage 326 is coupled to the node N1.

The dual-channel operational amplifier circuit disclosed in the above-mentioned embodiments of the present invention has many advantages, and only some of the advantages are listed below:

The dual-channel operational amplifier circuit of the present invention receives positive polarity data and negative polarity data by using the input stage and gain stage of a single operational amplifier, and simultaneously switches the input stage and the gain stage to the operating voltage range of the same polarity when performing polarity conversion , and switch to the output stage of the same polarity, so that the data of different polarities of a single output node can be processed by the same input stage and gain stage, avoiding abnormal display problems caused by voltage offsets, without the need for additional Compensation Mechanism. In addition, since the input stage, the gain stage and the output stage of the dual-channel operational amplifier circuit all operate in the half-voltage operation mode by switching the switch, current consumption can be saved.

To sum up, although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Those skilled in the technical field to which the present invention belongs may make various equivalent changes or substitutions without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the appended claims of the application.

Claims (1)

1. A dual-channel operational amplifier circuit, comprising: a first operational amplifier having a first input stage, a first gain stage, and a first output stage; and a second operational amplifier having a second input stage, a second gain stage and a second output stage, the second operational amplifier and the first operational amplifier are operated in a half-voltage operation mode; a plurality of first switches, a plurality of second switches, a plurality of third switches and a plurality of fourth switches; Wherein, in a first frame period, the first switches are turned on and the second switches are turned off, the operating voltage range of the dual-channel operational amplifier switching the first input stage, the first gain stage and the first output stage is Between an operating voltage and half of the operating voltage, a positive polarity signal is output to a first node through the first input stage, the first gain stage and the first output stage, the third switches are turned on and the fourth The switch is turned off, the dual-channel operational amplifier switches the operating voltage range of the second input stage, the second gain stage and the second output stage to be between the half operating voltage and a ground voltage, so that a negative polarity signal passes through the first Two input stages, the second gain stage and the second output stage output to a second node; Wherein, in a second frame period, the first switches are turned off and the second switches are turned on, the operating voltage range of the dual-channel operational amplifier switching the second input stage, the second gain stage and the first output stage is Between the operating voltage and the half operating voltage, the positive polarity signal is output to the second node through the second input stage, the second gain stage and the first output stage, the third switches are turned off and the fourth The switch is turned on, and the operating voltage range of the first input stage, the first gain stage, and the second output stage of the dual-channel operational amplifier is between the half operating voltage and the ground voltage, so that the negative polarity signal passes through the The first input stage, the first gain stage and the second output stage output to the first node.

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