An ultra‐thin oxide sub‐1 V CMOS bandgap voltage reference

Abstract

ABSTRACTThis paper presents a sub‐1 V CMOS bandgap voltage reference that accounts for the presence of direct tunneling‐induced gate current. This current increases exponentially with decreasing oxide thickness and is especially prevalent in traditional (non‐high‐κ/metal gate) ultra‐thin oxide CMOS technologies (tox < 3 nm), where it invalidates the simplifying design assumption of infinite gate resistance. The developed reference (average temperature coefficient, TC_AVG, of 22.5 ppm/°C) overcomes direct tunneling by employing circuit techniques that minimize, balance, and cancel its effects. It is compared to a thick‐oxide voltage reference (TC_AVG = 14.0 ppm/°C) as a means of demonstrating that ultra‐thin oxide MOSFETs can achieve performance similar to that of more expensive thick(er) oxide MOSFETs and that they can be used to design the analog component of a mixed‐signal system. The reference was investigated in a 65 nm CMOS technology with a nominal VDD of 1 V and a physical oxide thickness of 1.25 nm. Copyright © 2013 John Wiley & Sons, Ltd.