AMSV Newsletter 2015

In IEEE Transactions on Electron Devices 2015
A Precision CMOS Voltage Reference Exploiting Silicon Bandgap
Narrowing Effect
Bo Wang, Man-Kay Law and Amine Bermak
From Wireless research line
Motivation
Architecture
Conventional precision voltage references
(BGRs) can be achieved by multiple temperature
trimmings and/or power hungry curvature
correction circuits that inevitably increases cost
and energy efficiencies. We exploit the intrinsic
temperature characteristics of the BJT itself to
reduce the BJT curvature and perform curvature
correction using the silicon bandgap narrowing
effect so as to avoid the power overhead of curvature
correction circuits by batch trimming.
Measurement results show that the BJT curvature
can be effectively reduced from its inherent
3.6 mV to 1.4 mV. The proposed BGR measures
a minimum temperature coefficient of 8.7 ppm/°
C and 4.1 ppm/°C from −55 °C to 125 °C after
batch trimming and curvature trimming, respectively.
Proposed BGR Topology with curvature reduction using bandgap
narrowing effect
Relationship between voltage and temperature showing the curvature reduction
and correction with convex (left) and concave (right) BJT intrinsic curvatures.
Implementation
Verification
(a)
Complete schematic of the proposed BGR using bandgap narrowing effect.
(b)
Chip micrograph of the proposed BGR
(a) Inaccuracy of V REF from 12 samples without trimming and after batch
trimming resistor R c1 at 25 °C (dotted lines indicates ± 3σ values); (b)
Measured BJT intrinsic curvature and V REF before and after the curvature
compensation.