Buck converter for on-chip reference generation
Date
2010
Authors
Rai, Abhay K., author
Collins, George, advisor
Yalin, Azer, committee member
Reising, Steven, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Most modern day chips use an on chip voltage reference, also known as a bandgap voltage reference generator, to provide a stable reference, independent of power supply voltage (VDD) ripples and compensated for temperature variations. When power supply voltage decreases as the process feature size (gate length) decreases, it imposes challenges in terms of headroom and other factors to achieve a stable bandgap voltage reference. It also needs to be scaled down to VDD/2 for practical uses and provide a common mode voltage of VDD/2 of on-chip circuits. This thesis discusses a buck converter which uses an alternative to pulse width modulation (PWM) for stable reference generation and directly generates a VDD/2 reference using a novel inductor ripple current cancellation technique, which cancels inductor ripple current and therefore does not require a large capacitance for filtering of inductor ripple. An alternative to the pulse width modulation (PWM) technique is proposed, which uses common mode bias and transconductance (gm) tuning to keep the reference output constant for variable loads, and a temperature compensation techniques is used to minimize temperature sensitivity.