A CMOS symmetric self-biased voltage reference

This paper presents a novel CMOS voltage reference circuit named symmetric self-biased voltage reference (SSVR), which enables not only to discard the voltage headroom issue of a conventional constant-g(m) current source and the inevitable need of an extra bias in a modified constant-g(m), current source, but also to maintain stable bias voltages with strong tolerance against significant variations of power supply and temperature. Test chips of the SSVR were implemented by using a 0.11-mu m CMOS process. Measured results demonstrate that the symmetric configuration of the proposed SSVR helps to achieve constant voltage references against the V-DD variation from 0.7 to 1.2V and the temperature variation from -15 degrees C to 125 degrees C. The fabricated chip consumes constant 18.5 mu A currents for 0.7 similar to 1.0-V supply voltages and its core occupies the area of 0.04 x 0.047 mm(2).