On the placement of critical devices in analog integrated circuits

摘要

The question of how to arrange devices (e.g. MOS transistors) in analog integrated circuits so that process variations on the chip affect the circuit's performance as little as possible is addressed. The answer to this question-a generalization of the common centroid technique-is outlined, and the solution for the specific input-transistor layout of a differential difference amplifier is presented. The method can be applied to other precision analog circuits, like multipliers. Placement of components like capacitors in switched-capacitor circuits can be treated analogously.