A Self-Testable Delta-Sigma Modulator for Built-on-Scribe-Line TFT LCD Source Driver Testing
Date Issued
2008
Date
2008
Author(s)
Yang, Chen-Yuan
Abstract
In this thesis, we present a low-cost wafer-level test methodology for the source driver ICs of liquid crystal displays; the idea is to realize the test circuitry on the wafer scribe line. The proposed technique not only substantially reduces the required ATE I/O channels but also eliminates the need of high-speed digitization units on the ATE. In this test circuitry, a first-order ΔΣ modulator is chosen as the digitizer to quantize the driver output voltage. The ΔΣ modulator can tolerate relatively high process variations and matching inaccuracy, which is the best candidate of A/D converter in our test circuit design. To ensure the reliability of the digitizer, a low-cost and efficient Design-for-Test(DfT) technique is also developed to characterize the integrator leakage of ΔΣ modulator. The proposed technique is a low-cost solution because it only adds two multiplexers to the modulator, utilizes DC voltage as the test stimulus, and estimates the integrator leakage by analyzing the digitized bit stream. This proposed method can also be applied to other ΔΣ modulator structures, e.q., higher-order and MASHtructures. Simulation results show that accurate estimations of the integrator leakage can be achieved even at the presence of noise.
Subjects
delta-sigma modulator
Design-for-Test
TFT LCD source driver
integrator leakage
mixed-signal testing
Type
thesis
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