液晶顯示源極驅動器高速自我測試方法與測試流程最佳化

由於輸出信號為類比電壓加上輸出腳位的數量眾多，液晶顯示器源極驅動器的測試成本相當高昂並且需要大量的測試時間。[1] 中提出了一個內建自我測試的架構。它藉由減少對混合信號測試機台和高成本探針卡的需求，降低測試的成本；然而這個架構卻需要更長的測試時間。在本論文中，我們發展了一個能夠在短時間之內達到高精確度的測試方法。首先我們針對上面提到的內建自我測試電路，提出一個兩階段的量測方式，在不影響精確度的前提下解決策是時間過長的問題。此方法等效上對不同的帶測電壓進行的不同解析度的量測，解決了測試時間和精確度之間的權衡問題。不論分析或模擬的結果皆顯示這個方法可以讓測試速度提高數十倍。我們也提出一個以三角積分調變器為基礎，用來測量並計算輸出電壓平均值的方法。這個方法可以計算出精確的平均值，而不需要精確的測量每一個電壓。最後，我們提出一個積體電路的測試成本函數。此函數考量了測試時間和測試時發生誤宰、誤放造成的損失。我們針對了本論文中提出的兩階段測試方法推導測試液晶顯示源極驅動器的成本函數。接著經過數值方法的計算，取得兩個量測階段超取樣頻率的最佳組合，以達到最小化測試成本的目的。

關鍵字

源極驅動器；混合信號測試；三角積分轉換器

並列摘要

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.

並列關鍵字

source driver ； mixed-signal testing ； delta-sigma modulator

參考文獻

[2] Hyeonuk Son, Jaewon Jang, Youbean Kim, Kicheol Kim, Incheol Kim and Sungho Kang, “A BIST Architecture for Multiple DACs in an LTPS TFT-LCD Source Driver IC,” International SoC Design Conference, pp. 120, 2009.

[5] J.-L. Huang and K.-T. Cheng, “A sigma-delta modulation BIST scheme for mixed-signal circuits,” in Asia and South Pacific Design Automation Conference, pp. 605–610, 2000.

[6] H.-C. Hong, B.-H. Lin, and C.-W. Wu, “Analysis and design of multiplebit high-order ∆-Σ modulator,” in Asia and South Pacific Design Automation Conference, pp. 419–424, 1997.

[7] K.-J. Lee, S.-J. Chang, R.-S. Tzeng, “A Sigma-Delta Modulation Based BIST Scheme for A/D Converters,” in IEEE Asian Test Symposium, pp.124-127, 2003.

[8] S. Ardalan and J. Paulos, “An analysis of nonlinear behavior in deltasigma modulators,” in IEEE Transactions on Circuits and Systems, vol. 34, pp. 593–603, Jun. 1987.

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液晶顯示源極驅動器高速自我測試方法與測試流程最佳化

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