DESIGN AND OPTIMIZATION OF A LOW DC OFFSET CMOS CURRENT-SOURCE DEDICATED TO IMPLANTABLE MINIATURIZED STIMULATORS

The main goal of our study is the design of a current-source (CS) base d on a miniaturized digital-to-analog converter (DAC). The primary app lication of this device is a wide range of neuromuscular implantable m icrostimulators. A great deal of attention was devoted to creating a f lexible, compact, and energy efficient circuit. A new design method ba sed on an optimization process involving area and linearity is thus pr oposed. Circuits obtained using this technique were characterized as h aving a 5-bit DAC resolution, with 2 mA peak output current, while req uiring around 0.01 mm(2) of chip area, using a 1.2 mu m CMOS technolog y. This paper also extends the method to create an improved current-so urce, designed to minimize the output DC offset and charge accumulatio n that are noxious for the stimulated neuromuscular tissues. Our analy sis of the proposed circuit configuration show that we can reach a sma ll DC offset error, without using any coupling capacitor, which tend t o be bulky, and not desirable in highly miniaturized implants.