Journal of the Institute of Electronics Engineers of Korea SD (대한전자공학회논문지SD)

The Institute of Electronics and Information Engineers (대한전자공학회)
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A High Voltage CMOS Rail-to-Rail Input/Output Operational Amplifier with Gain enhancement

전압 이득 향상을 위한 고전압 CMOS Rail-to-Rail 입/출력 OP-AMP 설계

  • An, Chang-Ho (School of Information and Communication Engineering, Sungkyunkwan University) ;
  • Lee, Seung-Kwon (Semiconductor Division, Samsung Electronics) ;
  • Jun, Young-Hyun (Semiconductor Division, Samsung Electronics) ;
  • Kong, Bai-Sun (School of Information and Communication Engineering, Sungkyunkwan University)
  • 안창호 (성균관대학교 전자전기컴퓨터공학과) ;
  • 이승권 (삼성전자(주) 반도체총괄) ;
  • 전영현 (삼성전자(주) 반도체총괄) ;
  • 공배선 (성균관대학교 전자전기컴퓨터공학과)
  • Published : 2007.10.25
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Abstract

A gain enhancement rail-to-rail buffer amplifier for liquid crystal display (LCD) source driver is proposed. An op-amp with extremely high gain is needed to decrease the offset voltage of the buffer amplifier. Cascoded floating current source and class-AB control block in the op-amp achieve a high voltage gain by reducing the channel length modulation effect in high voltage technologies. HSPICE simulation in $1\;{\mu}V$ 15 V CMOS process demonstrates that voltage gain is increased by 30 dB. The offset voltage is improved from 6.84 mV to $400\;{\mu}V$. Proposed op-amp is fabricated in an LCD source driver IC and overall system offset voltage is decreased by 2 mV.

본 논문에서는LCD (Liquid Crystal Display) source driver IC에서 사용되는 고전압 op-amp의 출력 편차를 개선하기 위하여 전압 이득을 향상한 CMOS rail-to-rail 입/출력 op-amp를 제안하였다. 제안된 op-amp는 15 V 이상의 고전압 MOSFET의 과도한 channel length modulation에 의한 전압 이득의 감소로 offset 전압이 커지는 문제를 해결하기 위하여 cascode 구조를 갖는 floating current source 및 class-AB control단을 채용하고 있다. 제안된 op-amp는 HSPICE 시뮬레이션을 통하여 전압 이득이 기존 대비 30 dB 향상됨을 확인하였으며, onset 전압은 기존 6.84 mV에서 $400\;{\mu}V$ 이하로 개선됨을 확인하였다. 또한, 제안된 op-amp가 적용된 LCD source driver IC의 실측 결과 출력 편차는 기존 대비 2 mV 향상됨을 확인하였다.

Keywords

References

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