Achieving high sensing in 0.5 nA for the driving pixel currents in AMOLEDs with settling time of 7 µs by a new external current sensing circuit


A new external current sensing circuit with baseline compensation for the active matrix organic light emitting diode (AMOLED) display is developed herein to achieve the sensing precision of 0.5 nA in pixel with 7 µs of settling time. Current sensing circuit incorporates a new push–pull transient current feedforward whereas the current analog to digital converter (CADC) based digital baseline current compensation incorporates an 11-bit current digital-to-analog converter, a current comparator and a digital control circuit with an 11-bit successive approximation register. The proposed integrated mixed signal IC drives a 6T1C pixel-based AMOLED panel with one horizontal time of 7.7 µs at a scan frequency of 60 Hz. The design readout chip can simultaneously sense and compensate TFT baseline current variation. The readout circuit and the baseline compensation circuit are implemented in the integrated chip with chip area of 125 μm × 46 μm and fabricated via TSMC T18 process. With the standard 3.3 V supply, experimental result shows that the overall power consumption of the chip is 988 µW watt. The minimum LSB current for the CADC is 10 nA and the maximum achievable sampling rate is 500 KS/s. The measured INL and DNL of CADC is 0.84 and 0.98 respectively. Despite of heavy data line parasitic capacitances (2.6 KΩ/20 pF) of the AMOLED display, experimental results show that the proposed circuit can sense 0.5 nA current within 7 µs of settling time. The sensing precision of 0.5 nA within 7 µs are the best among all reported literature to date whereas the current sense range (0.5–500 nA), system sampling rate (142 KS/s), INL (0.84) and DNL (0.98) of the CADC is approximately comparable among all reported.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14
Fig. 15
Fig. 16
Fig. 17
Fig. 18
Fig. 19
Fig. 20
Fig. 21
Fig. 22
Fig. 23
Fig. 24
Fig. 25
Fig. 26
Fig. 27
Fig. 28
Fig. 29
Fig. 30
Fig. 31
Fig. 32
Fig. 33
Fig. 34
Fig. 35
Fig. 36
Fig. 37
Fig. 38
Fig. 39


  1. Agarwal A, Kim YB, Sonkusale S (2005) Low power current mode ADC for CMOS sensor IC. In: 2005 IEEE international symposium on circuits and systems, Kobe, pp 584–587

  2. Ashtiani SJ, Nathan A (2009) A driving scheme for active-matrix organic light-emitting diode displays based on current feedback. J Disp. Technol 5(7):257–264

    Article  Google Scholar 

  3. Banerjee SS (2014) 500 MHz differential latched current comparator for calibration of current steering DAC. In: IEEE students’ technology symposium (TechSym)

  4. Bang JS, Kim HS, Park SH, Kim GH, Cho GH (2014) A real-time TFT compensation through power line current sensing for high-resolution AMOLED displays. In: SID 2014 DIGEST, pp 724–727

  5. Bang JS, Kim HS, Kim KD, Kwon OJ, Shin CS, Lee J, Cho GH (2016) A hybrid AMOLED driver IC for real-time TFT nonuniformity compensation. IEEE J Solid-State Circuits 51(4):966–978

    Article  Google Scholar 

  6. Chaji GR, Nathan A (2005) A fast settling current driver based on the CCII for AMOLED displays. IEEE J Disp Technol 1:283–288

    Article  Google Scholar 

  7. Genoe J, Obata K, Ameys M, Myny K, Ke TH, Nag M, Steudel S, Schols S, Maas J, Tripathi A, Steen JLPJ, Ellis T, Gelinck GH, Heremans P (2015) Integrated line driver for digital pulse-width modulation driven AMOLED displays on flex. IEEE J Solid-State Circuits 50(1):282–290

    Article  Google Scholar 

  8. Huang Q, Feng J (2013) A 10-bit nanoampere level current-steering digital to analog converter. In: 2013 13th international symposium on communications and information technologies (ISCIT), Surat Thani, pp 261–265

  9. Huang P-H, Lin H, Lin Y-T (2006) A simple subthreshold CMOS voltage reference circuit with channel-length modulation compensation. IEEE Trans Circuits Syst II Express Briefs 53(9):882–885

    Article  Google Scholar 

  10. In HJ, Kwon OK (2009) External compensation of nonuniform electrical characteristics of thin-film transistors and degradation of OLED devices in AMOLED displays. IEEE Electron Device Lett 30(4):377–379

    Article  Google Scholar 

  11. In HJ, Choi BD, Chung HK, Kwon OK (2006) Current-sensing and voltage-feedback driving method for large-area high-resolution active matrix organic light emitting diodes. Jpn J Appl Phys 45(5B):4396–4401

    Article  Google Scholar 

  12. Jeon JY, Jeon YJ, Son YS, Lee KC, Lee HM, Jung SC, Lee KH, Cho GH (2008) A direct-type fast feedback current driver for medium-to large size AMOLED displays. In: Proceedings of the IEEE ISSCC digest of technical papers, pp 174–604

  13. Jeon Y, Jeon J, Son Y, Huh J, Cho GH (2010) A high-speed current-mode data driver with push-pull transient current feedforward for full-HD AMOLED displays. IEEE J Solid-State Circuits 45(9):1881–1895

    Article  Google Scholar 

  14. Jin M, Im H, Song M, Kim SY (2018) Nano-ampere current sensing technique for OLED mobile displays. In: 2018 international SoC design conference (ISOCC), Daegu, Korea (South), pp 101–102

  15. Jin M, Im H, Song M, Kim YS (2018) Nano-ampere current sensing technique for OLED mobile displays. In: 2018 international SoC design conference (ISOCC), Daegu, Korea (South), pp 101–102

  16. Komiya N, Oh NC, Eom K, Kim Y, Park S, Kim S (2004) A 2.0-in. AMOLED panel with voltage programming pixel circuits and point scanning data driver circuits. In: Proceedings of the international display workshops (IDW’04), pp 283–286

  17. Lin LC, Lai PC, Shih WL, Hung CC, Lai PC, Lin YT, Liu HK, Wang HT (2019) Compensation pixel circuit to improve image quality for mobile AMOLED displays. IEEE J Solid-State Circuits 54(2):489–500

    Article  Google Scholar 

  18. Lu L, Deng L, Ke J, Liao C, Huang S (2019) A fast ramp-voltage-based current programming driver for AMOLED display. IEEE Trans Circuits Syst II Express Briefs 66(7):1129–1133

    Article  Google Scholar 

  19. Maghsoudloo E, Moradi S, Arian A (2012) Current mode sensor interface system for biomedical implantable applications. In: 20th Iranian conference on electrical engineering (ICEE2012), Tehran, pp 26–29

  20. Men G-Y, Cheng Y-P, Chao PC-P, Yang C-C, Pribadi EF (2016) A charge pump with MPPT circuit employed in batteryless photovoltaic IoT tags. ASME 2016 conference on information storage and processing systems, pp V001T09A003

  21. Nathan A, Kumar A, Sakariya K, Servati P, Sambandan S, Striakhilev D (2004) Amorphous silicon thin film transistor circuit integration for organic LED displays on glass and plastic. IEEE J Solid-State Circuits 39(9):1477–1486

    Article  Google Scholar 

  22. Pilani B, Goa KB (2014) A 8-bit SAR ADC using current mode approach for bio-medical applications. In: IEEE signal processing and networking (NCCSN)

  23. Ying D, Chen P, Tseng C, Lo Y, Hall AD (2019) A sub-pA current sensing front-end for transient induced molecular spectroscopy. In: 2019 symposium on VLSI circuits, Kyoto, Japan, pp C316–C317

Download references


The authors appreciate the supports from National Chip Implementation Center Taiwan. This study is supported by Ministry of Science and Technology, Taiwan Grant No. MOST 107-2221-E-009-166-MY2, MOST 107-2218-E-009-006, MOST 107-3017-F-009-003, MOST 107-2622-E-009-025-CC2, MOST 108-2823-8-009-002,109-2622-8-009 -018 -TE1, and MOST 108-2623-E-009-004-D. It was also supported in part by the Novel Bioengineering and Technological Approaches to Solve Two Major Health Problems in Taiwan sponsored by the Taiwan Ministry of Science and Technology Academic Excellence Program under Grant Number: MOST 108-2633-B-009-001. This work was financially supported by the “Center for Intelligent Drug Systems and Smart Bio-devices (IDS2B)” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan. It was also supported in part by Hsinchu Science Park Bureau, MOST Grant No. 108A31B. A part of this work was funded by AU Optronics Corp (AUO), Taiwan.

Author information



Corresponding author

Correspondence to Paul C.-P. Chao.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary material 1 (MP4 4443 kb)

Supplementary material 2 (MOV 2103 kb)

Supplementary material 3 (MP4 5345 kb)

Supplementary material 4 (MOV 1945 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Pandey, R.K., Huang, T.H., Ho, W. et al. Achieving high sensing in 0.5 nA for the driving pixel currents in AMOLEDs with settling time of 7 µs by a new external current sensing circuit. Microsyst Technol (2020).

Download citation