Abstract

Active-matrix organic light-emitting-diode (AMOLED) displays based on amorphous hydrogenated silicon (a-Si:H) thin-film transistors (TFTs) are the state of the art in display technology, owing to the feasilibility of low-cost fabrication and accessability to well-established TFT-LCD fabrication. While the a-Si:H TFT offers excellent matching of device properties over large areas, it suffers from a gate-bias-dependent threshold voltage shift in time, leading to grayscale inaccuracies. In order to counter this problem, many compensation circuits have been designed. The purpose of the compensation circuit is to estimate the threshold voltage shift in driver TFTs and apply a correction so as to maintain a constant brightness. However, all of the compensation circuits designed to date suffer from low spatial and temporal resolution and reliability issues or high cost due to the use of custom-made CMOS technology. In this paper, we focus on building AMOLED display systems solely based on a-Si:H TFT technology along with the use of off-the-shelf CMOS components to lower costs. Furthermore, we achieve high spatial and temporal resolution and high yield with the use of a two-TFT voltage programmed pixel circuit along with a statistical based external calibration circuit.

© 2007 IEEE

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  1. J.-C. Goh, J. Jang, K.-S. Cho, C.-K. Kim, "A new a-Si:H thin-film transistor pixel circuit for active-matrix organic light emitting diodes," IEEE Electron Device Lett. 24, 583-585 (2003).
  2. J. L. Sanford, F. R. Libsch, "TFT AMOLED pixel circuits and driving methods," Proc. Soc. Inf. Display (2003) pp. 10-13.
  3. S. Jafarabadiashtiani, G. Chaji, S. Sambandan, D. Striakhilev, A. Nathan, P. Servati, "A new driving method for a-Si AMOLED displays based on voltage feedback," Proc. Soc. Inf. Display (2005) pp. 316-319.
  4. S. Sambandan, A. Nathan, "Fuzzy current control using current mode WTA-LTA circuits in flexible organic displays," Proc. 48th IEEE Midwest Symp. on Circuits Syst. (2005) pp. 1609-1612.
  5. G. R. Chaji, P. Servati, A. Nathan, "Driving scheme for stable operation of 2 TFT a-Si AMOLED pixel," Electon. Lett. 41, 499-500 (2005).
  6. A. Nathan, A. Kumar, K. Sakariya, P. Servati, S. Sambandan, D. Striakhilev, "Amorphous silicon thin film transistor circuit integration for organic LED displays on glass and plastic," IEEE J. Solid-State Circuits 39, 1477-1486 (2004).
  7. S. Sambandan, A. Nathan, "Stable organic LED displays using RMS estimation of threshold voltage dispersion," IEEE Trans. Circuits Syst. II, Exp. Briefs 53, 941-945 (2006).
  8. M. J. Powell, "The physics of amorphous-silicon thin film transistors," IEEE Trans. Electron Devices 36, 2764-2769 (1989).
  9. M. J. Powell, S. C. Deane, W. I. Milne, "Bias-stress-induced creation and removal of dangling-bond states in amorphous silicon thin film transistors," Appl. Phys. Lett. 60, 207-209 (1992).
  10. R. B. Wehrspohn, M. J. Powell, S. C. Deane, "Kinetics of defect creation in amorphous silicon thin film transistors," J. Appl. Phys. 93, 5780-5788 (2003).
  11. M. J. Powell, C. van Berkel, A. R. Franklin, S. C. Deane, W. I. Milne, "Defect pool in amorphous-silicon thin-film transistors," Phys. Rev. B 45, 4160-4170 (1992).
  12. F. R. Libsch, J. Kanicki, "Bias-stress-induced stretched-exponential time dependence of charge injection and trapping in amorphous silicon thin film transistors," Appl. Phys. Lett. 62, 1286-1288 (1993).
  13. C.-S. Chiang, J. Kanicki, K. Takechi, "Electrical instability in hydrogenated amorphous silicon thin-film transistors for active matrix liquid crystal displays," Jpn. J. Appl. Phys. 37, 4704-4710 (1998).
  14. K. S. Karim, A. Nathan, M. Hack, W. I. Milne, "Drain-bias dependence of threshold voltage stability of amorphous silicon TFTs," IEEE Electron Device Lett. 25, 188-190 (2004).
  15. S. Sambandan, L. Zhu, D. Striakhilev, P. Servati, A. Nathan, "Markov model for threshold voltage shift in amorphous silicon TFTs for variable gate bias," IEEE Electron Device Lett. 26, 375-377 (2005).
  16. S. Sambandan, A. Nathan, "Equivalent circuit for $V_{T}$ shift in a-Si:H TFTs based on a probabilistic analysis of electron population dynamics," IEEE Trans. Electron Device 53, 2306-2311 (2006).
  17. M. Hack, M. S. Shur, J. G. Shaw, "Physical models for amorphous-silicon thin-film transistors and their implementation in a circuit simulation program," IEEE Trans. Electron Devices 36, 2764-2769 (1989).
  18. K. S. Karim, P. Servati, N. Mohan, A. Nathan, J. A. Rowlands, "VHDL-AMS modeling and simulation of a passive pixel sensor in a-Si:H technology for medical imaging," Proc. Int. Symp. Circuits Syst. (2001) pp. 479-482.
  19. S. Sambandan, D. Striakhilev, A. Nathan, "Circuit and device level optimisation for high performance a-Si:H TFT based AMOLED displays," J. Display Technol. 2, 52-59 (2006).
  20. S. Sambandan, A. Nathan, "Circuit techniques for organic and amorphous semiconductor based field effect transistors," Proc. Eur. Solid State Circuits Conf. (2006) pp. 70-73.
  21. B. Sheu, J.-H. Shieh, M. Patil, "Modeling charge injection in MOS analog switches," IEEE Trans. Circuits Syst. CAS–34, 214-216 (1987).
  22. G. Wegmann, E. A. Vittoz, F. Rahali, "Charge injection in analog MOS switches," IEEE J. Solid-State Circuits SC–22, 1091-1097 (1987).

2006 (3)

S. Sambandan, A. Nathan, "Stable organic LED displays using RMS estimation of threshold voltage dispersion," IEEE Trans. Circuits Syst. II, Exp. Briefs 53, 941-945 (2006).

S. Sambandan, A. Nathan, "Equivalent circuit for $V_{T}$ shift in a-Si:H TFTs based on a probabilistic analysis of electron population dynamics," IEEE Trans. Electron Device 53, 2306-2311 (2006).

S. Sambandan, D. Striakhilev, A. Nathan, "Circuit and device level optimisation for high performance a-Si:H TFT based AMOLED displays," J. Display Technol. 2, 52-59 (2006).

2005 (2)

S. Sambandan, L. Zhu, D. Striakhilev, P. Servati, A. Nathan, "Markov model for threshold voltage shift in amorphous silicon TFTs for variable gate bias," IEEE Electron Device Lett. 26, 375-377 (2005).

G. R. Chaji, P. Servati, A. Nathan, "Driving scheme for stable operation of 2 TFT a-Si AMOLED pixel," Electon. Lett. 41, 499-500 (2005).

2004 (2)

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

K. S. Karim, A. Nathan, M. Hack, W. I. Milne, "Drain-bias dependence of threshold voltage stability of amorphous silicon TFTs," IEEE Electron Device Lett. 25, 188-190 (2004).

2003 (2)

J.-C. Goh, J. Jang, K.-S. Cho, C.-K. Kim, "A new a-Si:H thin-film transistor pixel circuit for active-matrix organic light emitting diodes," IEEE Electron Device Lett. 24, 583-585 (2003).

R. B. Wehrspohn, M. J. Powell, S. C. Deane, "Kinetics of defect creation in amorphous silicon thin film transistors," J. Appl. Phys. 93, 5780-5788 (2003).

1998 (1)

C.-S. Chiang, J. Kanicki, K. Takechi, "Electrical instability in hydrogenated amorphous silicon thin-film transistors for active matrix liquid crystal displays," Jpn. J. Appl. Phys. 37, 4704-4710 (1998).

1993 (1)

F. R. Libsch, J. Kanicki, "Bias-stress-induced stretched-exponential time dependence of charge injection and trapping in amorphous silicon thin film transistors," Appl. Phys. Lett. 62, 1286-1288 (1993).

1992 (2)

M. J. Powell, C. van Berkel, A. R. Franklin, S. C. Deane, W. I. Milne, "Defect pool in amorphous-silicon thin-film transistors," Phys. Rev. B 45, 4160-4170 (1992).

M. J. Powell, S. C. Deane, W. I. Milne, "Bias-stress-induced creation and removal of dangling-bond states in amorphous silicon thin film transistors," Appl. Phys. Lett. 60, 207-209 (1992).

1989 (2)

M. J. Powell, "The physics of amorphous-silicon thin film transistors," IEEE Trans. Electron Devices 36, 2764-2769 (1989).

M. Hack, M. S. Shur, J. G. Shaw, "Physical models for amorphous-silicon thin-film transistors and their implementation in a circuit simulation program," IEEE Trans. Electron Devices 36, 2764-2769 (1989).

1987 (2)

B. Sheu, J.-H. Shieh, M. Patil, "Modeling charge injection in MOS analog switches," IEEE Trans. Circuits Syst. CAS–34, 214-216 (1987).

G. Wegmann, E. A. Vittoz, F. Rahali, "Charge injection in analog MOS switches," IEEE J. Solid-State Circuits SC–22, 1091-1097 (1987).

Appl. Phys. Lett. (2)

M. J. Powell, S. C. Deane, W. I. Milne, "Bias-stress-induced creation and removal of dangling-bond states in amorphous silicon thin film transistors," Appl. Phys. Lett. 60, 207-209 (1992).

F. R. Libsch, J. Kanicki, "Bias-stress-induced stretched-exponential time dependence of charge injection and trapping in amorphous silicon thin film transistors," Appl. Phys. Lett. 62, 1286-1288 (1993).

Electon. Lett. (1)

G. R. Chaji, P. Servati, A. Nathan, "Driving scheme for stable operation of 2 TFT a-Si AMOLED pixel," Electon. Lett. 41, 499-500 (2005).

IEEE J. Solid-State Circuits (1)

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

IEEE Electron Device Lett. (2)

J.-C. Goh, J. Jang, K.-S. Cho, C.-K. Kim, "A new a-Si:H thin-film transistor pixel circuit for active-matrix organic light emitting diodes," IEEE Electron Device Lett. 24, 583-585 (2003).

S. Sambandan, L. Zhu, D. Striakhilev, P. Servati, A. Nathan, "Markov model for threshold voltage shift in amorphous silicon TFTs for variable gate bias," IEEE Electron Device Lett. 26, 375-377 (2005).

IEEE Electron Device Lett. (1)

K. S. Karim, A. Nathan, M. Hack, W. I. Milne, "Drain-bias dependence of threshold voltage stability of amorphous silicon TFTs," IEEE Electron Device Lett. 25, 188-190 (2004).

IEEE J. Solid-State Circuits (1)

G. Wegmann, E. A. Vittoz, F. Rahali, "Charge injection in analog MOS switches," IEEE J. Solid-State Circuits SC–22, 1091-1097 (1987).

IEEE Trans. Circuits Syst. II, Exp. Briefs (1)

S. Sambandan, A. Nathan, "Stable organic LED displays using RMS estimation of threshold voltage dispersion," IEEE Trans. Circuits Syst. II, Exp. Briefs 53, 941-945 (2006).

IEEE Trans. Circuits Syst. (1)

B. Sheu, J.-H. Shieh, M. Patil, "Modeling charge injection in MOS analog switches," IEEE Trans. Circuits Syst. CAS–34, 214-216 (1987).

IEEE Trans. Electron Device (1)

S. Sambandan, A. Nathan, "Equivalent circuit for $V_{T}$ shift in a-Si:H TFTs based on a probabilistic analysis of electron population dynamics," IEEE Trans. Electron Device 53, 2306-2311 (2006).

IEEE Trans. Electron Devices (2)

M. Hack, M. S. Shur, J. G. Shaw, "Physical models for amorphous-silicon thin-film transistors and their implementation in a circuit simulation program," IEEE Trans. Electron Devices 36, 2764-2769 (1989).

M. J. Powell, "The physics of amorphous-silicon thin film transistors," IEEE Trans. Electron Devices 36, 2764-2769 (1989).

J. Display Technol. (1)

S. Sambandan, D. Striakhilev, A. Nathan, "Circuit and device level optimisation for high performance a-Si:H TFT based AMOLED displays," J. Display Technol. 2, 52-59 (2006).

J. Appl. Phys. (1)

R. B. Wehrspohn, M. J. Powell, S. C. Deane, "Kinetics of defect creation in amorphous silicon thin film transistors," J. Appl. Phys. 93, 5780-5788 (2003).

Jpn. J. Appl. Phys. (1)

C.-S. Chiang, J. Kanicki, K. Takechi, "Electrical instability in hydrogenated amorphous silicon thin-film transistors for active matrix liquid crystal displays," Jpn. J. Appl. Phys. 37, 4704-4710 (1998).

Phys. Rev. B (1)

M. J. Powell, C. van Berkel, A. R. Franklin, S. C. Deane, W. I. Milne, "Defect pool in amorphous-silicon thin-film transistors," Phys. Rev. B 45, 4160-4170 (1992).

Other (5)

K. S. Karim, P. Servati, N. Mohan, A. Nathan, J. A. Rowlands, "VHDL-AMS modeling and simulation of a passive pixel sensor in a-Si:H technology for medical imaging," Proc. Int. Symp. Circuits Syst. (2001) pp. 479-482.

J. L. Sanford, F. R. Libsch, "TFT AMOLED pixel circuits and driving methods," Proc. Soc. Inf. Display (2003) pp. 10-13.

S. Jafarabadiashtiani, G. Chaji, S. Sambandan, D. Striakhilev, A. Nathan, P. Servati, "A new driving method for a-Si AMOLED displays based on voltage feedback," Proc. Soc. Inf. Display (2005) pp. 316-319.

S. Sambandan, A. Nathan, "Fuzzy current control using current mode WTA-LTA circuits in flexible organic displays," Proc. 48th IEEE Midwest Symp. on Circuits Syst. (2005) pp. 1609-1612.

S. Sambandan, A. Nathan, "Circuit techniques for organic and amorphous semiconductor based field effect transistors," Proc. Eur. Solid State Circuits Conf. (2006) pp. 70-73.

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