Non-idealities in analog circuits design: What does it really mean?

Abstract

The aim of this contribution is to show why sources of non-idealities are actually a concept of reason in order to define tradeoffs in the design of analog circuits. A tradeoff is commonly picked up from an analytical design-model, which tries to explain a given phenomenon under study by using physical theories underlying the role of non-idealities in the design of accurate analog-circuits. Since accuracy is commonly used as a measure rule for minimizing the unwanted effect of non-idealities on the circuit performance, this paper underlines that non-idealities reported in open literature shown that any analog circuit is designed in a custom way, in which just some non-idealities are minimized in order to fulfill specific design specifications, i.e. sources of non-idealities do not necessarily include all existing ones but just those affecting -according the experience of the designer - the circuit's performance. Thus, what non-idealities have to be minimized in an analog circuit design is a question usually answered by reachable tradeoffs. This paper addresses difficulties (i.e. open problems) about silicon-based analog circuit design. So, analog design is not art, but an engineering activity supported in physical theories. Analog design demands not only accurate design models, and suitable simulation tools, but also a well-defined design methodology, elsewhere trial-and-error practices force to the analog-circuit designer to include substantial design margin and risk yield loss, and also provide little design knowledge.