Local matching-based multichannel LED constant current source driving circuit
A driving circuit and constant current source technology, which is applied in the field of low-mismatch multi-channel LED constant-current source drive circuit structure, can solve problems such as mismatching of different channels, long distances, mismatch reduction of power tubes, etc., and achieve insensitivity to process deviations , improve the effects of copy matching and copy mismatch reduction
Inactive Publication Date: 2014-09-24
PEKING UNIV
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Problems solved by technology
It can be found that due to the large area of the power tube, for a multi-channel LED drive circuit, different channels are located at different positions on the layout, not only far from the position of Mref, but also very far from the distance between different channels. The power tube cannot or is difficult to reduce the mismatch by doing local matching on the layout, such as common centroid matching
Therefore, the process deviation is the main reason for the mismatch between different channels
Method used
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[0016] The technical solutions of the present invention will be further described in detail through specific embodiments below in conjunction with the accompanying drawings.
[0017] image 3 For the concrete circuit diagram of the structural embodiment that the present invention proposes, as image 3 As shown in the figure, there are 4 channels (n=4), channel1-1, channel1-2, channel2-1, channel2-2, and every 2 channels share one Mref branch (k=4 / 2=2 ), channel1-1, channel1-2 share the Mref1 branch, use the op amp to copy VD1, channel2-1, channel2-2 share the Mref2 branch, use the op amp to copy VD2. The Current Source Mirror in the structure diagram is the first-stage current mirror. Copying the previous-stage current source ID generates two current sources Iref1 and Iref2 passing through Mref. This copying process produces a mismatch; the second mismatch is the corresponding channel pair The replication mismatch of Mref, where channel1-1, channel1-2 duplicates Iref1, chann...
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The invention, which belongs to the microelectronic and LED drive technology field, provides a local matching-based multichannel LED constant current source driving circuit structure with low mismatching. The circuit comprises a VG generator, a current source ID, a current source mirror, n channels and k Mref subcircuits. More specifically, the VG generator generates grid voltages provided for a power tube and a Mref in the circuit according to the circuit demand; the n channels share a VG in common; the current source ID reproduces current sources for different channel in the system; the current source mirror reproduces the ID and generates k different equal current sources that respectively flow through the k Mref subcircuits. According to the provided circuit structure, a local matching measure can be taken, thereby substantially reducing the total reproduction mismatching.
Description
technical field [0001] The invention relates to a low-mismatch multi-channel LED constant current source drive circuit structure based on local matching, and belongs to the technical fields of microelectronics and LED drive. Background technique [0002] At present, LED screens are widely used, and various industries and government departments such as telecommunications, postal services, finance, transportation, and stadiums have great demand for LED screens. Since the LED is a device with sensitive characteristics, and it changes significantly with the temperature. After the LED lamp is greater than the conduction threshold voltage, the current on it changes drastically with the change of voltage, and the brightness is proportional to the current on the LED, so the LED driver is required. Ensure the reliability and display consistency of LED. The current matching between channels can ensure the consistency when different pixels display the same gray scale and the linearity...
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IPC IPC(8): G09G3/32H05B37/02
Inventor 黄泽鲁文高余力澜王冠男王钊尹航张雅聪陈中建吉利久
Owner PEKING UNIV