The dominance of digital design activity, has not resulted in any let-up in
innovation by analogue designers, especially with respect to op-amps. Rece
ntly, op-amps have been introduced with a shut down mode which allows lower
ing of the supply current to a few nanoamperes. Almost all systems require
a finite amount of "analogue glue", and this article will discuss using som
e of these devices by taking advantage of their rather unique properties.