An Area-Efficient 10-Bit Buffer-Reused DAC for AMOLED Column Driver ICs

• Main Authors: Ming Xia, Zunkai Huang, Li Tian, Ning Wang, Yongxin Zhu, Hui Wang, Songlin Feng
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: Electronics
• Subjects: amoled displays; digital-to-analog converter (dac); output buffer; column driver
• Online Access: https://www.mdpi.com/2079-9292/9/2/208

In this paper, we proposed an area-efficient 10-bit digital-to-analog converter (DAC) with buffer-reusing method to dramatically relief the severe area exploding issue in high-definition active-matrix organic light-emitting diode (AMOLED) driver integrated circuits (ICs). In our design, we implement the functionalities of a large number of switches and capacitors in conventional DAC by a compact internal buffer. Furthermore, we minimize the buffer capacity requirement by elaborately reusing the indispensable output buffer in the typical column driver. In this way, we can cut down nearly a half of the decoder-switches and simultaneously reduce the capacitor size from 8 <i>C</i> to 3 <i>C</i> without designing an intricate and power-consuming amplifier separately. A prototype 6-channel column driver employing the proposed buffer-reused DAC was fabricated by 0.35 &#956;m 2P3M BCD (Bipolar, CMOS, DMOS) process and its effective layout area per channel is 0.0429 mm², which is 42.8% smaller than that of the conventional 10-bit R-C DAC. Besides, the measured differential nonlinearity (DNL) and integral nonlinearity (INL) are 0.514 LSB/0.631 LSB, respectively and the maximum value of inter-channel deviation voltage output (DVO) is 3.25 mV. The settling time within 5.6 &#956;s is readily achieved under 1.5 k&#937;-resistance and 100 pF-capacitance load. Measurement results indicate that the proposed buffer-reused DAC can successfully minimize the die area while maintaining other required performances.