High-precision Low-power Voltage Follower For Hardware Signal Processing

A specific application CMOS voltage follower is presented, which is well suited to be used as a component of VLSI analog electronics such as hardware implemented artificial neural networks (ANN's) or switched-capacitor filters (SC-filters). The main advantages of the follower are: a very high precision of operation and low power consumption. Another advantage is a low input capacitance (about 2fF) and extremely high input resistance. Compared with general purpose followers, its disadvantage is a restricted range of input voltage variations. This is the price we pay for the achieved positive features. Apart from the general idea and some previous versions of the follower, a new circuit realization is presented. SPICE simulation results concerning layouts made for a 0.35mum CMOS process are shown. These results are in good agreement with theoretical predictions as well as experimental results achieved for a 0.8mum prototype. Prototypes designed for the 0.18mum technology are currently being fabricated (in cooperation with University of Alberta in Canada) and no measurements have been performed yet