A 0.7-V Opamp in Scaled Low-Standby-Power FinFET Technology

Shin-ichi O'UCHI  Kazuhiko ENDO  Takashi MATSUKAWA  Yongxun LIU  Tadashi NAKAGAWA  Yuki ISHIKAWA  Junichi TSUKADA  Hiromi YAMAUCHI  Toshihiro SEKIGAWA  Hanpei KOIKE  Kunihiro SAKAMOTO  Meishoku MASAHARA  

IEICE TRANSACTIONS on Electronics   Vol.E95-C    No.4    pp.686-695
Publication Date: 2012/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.686
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Solid-State Circuit Design – Architecture, Circuit, Device and Design Methodology)
Common-Double-Gate FinFET,  Independent-Double-Gate FinFET,  common-mode voltage range,  low voltage,  differential amplifier,  source follower,  

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This paper demonstrates a FinFET operational amplifier (opamp), which is suitable to be integrated with digital circuits in a scaled low-standby-power (LSTP) technology and operates at extremely low voltage. The opamp is consisting of an adaptive threshold-voltage (Vt) differential pair and a low-voltage source follower using independent-double-gate- (IDG-) FinFETs. These two components enable the opamp to extend the common-mode voltage range (CMR) below the nominal Vt even if the supply voltage is less than 1.0 V. The opamp was implemented by our FinFET technology co-integrating common-DG- (CDG-) and IDG-FinFETs. More than 40-dB DC gain and 1-MHz gain-bandwidth product in the 500-mV-wide input CMR at the supply voltage of 0.7 V was estimated with SPICE simulation. The fabricated chip successfully demonstrated the 0.7-V operation with the 480-mV-wide CMR, even though the nominal Vt was 400 mV.