A robust deep submicron programmable DC voltage generator

An efficient technique for generating accurate on-chip DC reference voltages is presented. The technique is based on filtering a digital pulse-modulated sequence in order to extract its average (DC) value. Simplicity is achieved by using a passive on-chip filter and by using an all-digital implementation of the modulator. Moreover, in addition to using pulse-width modulation to encode the value of the output DC level, we propose the use of pulse-density modulation as a more viable technique. The latter has the advantage of using a significantly smaller filter, which translates into a smaller implementation area and a faster settling time. The technique was successfully demonstrated using a prototype IC in a 0.35 /spl mu/m CMOS process.