TFT LCD Source Driver High Speed Testing Method and Test Flow Optimization
Date Issued
2010
Date
2010
Author(s)
Lin, Wang-An
Abstract
Output diffusion testing of LCD source driver IC is very expensive and consumes very long test time due to its large amount of output pads and analog measurement requirement. A BIST structure has been proposed in to reduce the cost. The BIST scheme can relax the requirements of high cost mixed-signal ATE (automatic test equation) and probe card, but the test time will be much longer.
In this thesis, we develop a testing methodology that can achieve high measurement accuracy without suffering long test time. First, we present a two-phase measurement method on the BIST structure to solve the trade-off between accuracy and test time. Both simulation and analysis result show that test time is reduced dozens of times with this method.
Second, a ΔΣ modulator-based average measurement method is proposed to compute the mean output voltage of all channels with the same grayscale. This method can achieve high resolution without having to measure each channel output precisely.
Finally, a cost function of IC testing considering the test time and penalties of overkill and test escape is proposed. The cost function of the proposed two-phase flow is derived and the best combination of over-sampling rates in two measurement phases can be defined by numerical computing to minimize the test cost.
Subjects
source driver
mixed-signal testing
delta-sigma modulator
Type
thesis
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