02-06-2012, 04:42 PM
A Low Supply Voltage CMOS Bandgap And Sub-threshold Voltage
A Low Supply Voltage CMOS Bandgap And Sub-threshold Voltage .ppt (Size: 2.71 MB / Downloads: 60)
Basic Idea
For generating a temperature independent voltage reference, we need
Voltage with negative TC (Temp Coeff.) : V1
Voltage with positive TC : V2
A circuit to linearly combine them(a1V1 + a2V2) such that net voltage has (almost) zero TC
Our Innovation
To generate dual voltage references
Bandgap reference (1.157 V)
Sub-threshold reference (326 mV)
Circuit for sub-threshold reference
M13 and M14 acts as Voltage Divider to producesub threshold output = 326 mV
Main Challenge
Short Channel Transistors do not follow square law characteristics => adjustment to ideal W/L values, through iteration for getting desired current