CMOS

The design of integrated circuits has fallen, traditionally, into two separate categories: analog (circuits that process continuous amplitude signals) and digital (circuits for processing discrete amplitude signals). At the present time, and for the foreseeable future, there is a push to implement analog circuits in digital CMOS processes to reduce cost and increase system functionality. The traditional design techniques used to implement analog circuits can no longer be used in these digital/analog (mixed-signal) systems because of the absence of precision analog components, such as capacitors and high-gain transistors, and the presence of noise from the substrate and the power connections.