Charge Pump Design for TFT-LCD Driver IC Using Stack-MIM Capacitor

Gyu-Ho LIM  Sung-Young SONG  Jeong-Hun PARK  Long-Zhen LI  Cheon-Hyo LEE  Tae-Yeong LEE  Gyu-Sam CHO  Mu-Hun PARK  Pan-Bong HA  Young-Hee KIM  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.6   pp.928-935
Publication Date: 2008/06/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.6.928
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
charge pump,  pumping capacitor,  stack-MIM,  clock driver,  TFT-LCD,  

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A cross-coupled charge pump with internal pumping capacitor, which is advantageous from a point of minimizing TFT-LCD driver IC module, is newly proposed in this paper. By using NMOS and PMOS diodes connected to boosting nodes from VIN nodes, the pumping node is precharged to the same value at the pumping node in starting pumping. Since the first-stage charge pump is designed differently from the other stage pumps, a back current of pumped charge from charge pumping node to input stage is prevented. As a pumping clock driver is located in front of pumping capacitor, the driving capacity is improved by reducing a voltage drop of the pumping clock line from parasitic resistor. Finally, a layout area is decreased more compared with the conventional cross-coupled charge pump by using a stack-MIM capacitor. A proposed charge pump for TFT-LCD driver IC is designed with 0.13 µm triple-well DDI process, fabricated, and tested.