Application of Fixator-Norator Pairs in Designing Active Loads and Current Mirrors in Analog Integrated Circuits

Design of analog integrated circuits is discussed in this paper. The emphasis is on the biasing design of ICs using Fixator-norator pairs. Fixators are used to keep the driver transistors biased at the desirable operating points while the pairing norators are used to allocate and specify the bias-supporting components. A bias-supporting component is shown to be one of the two categories: 1) a DC voltage source or a DC current source/sink or 2) a power-conducting component. A power-conducting component is typically a resistor in lumped circuits but an active load or current mirror in an analog IC. Three types of active loads are introduced and their design is also discussed in this paper. Two examples, one in bipolar and one in CMOS technology, demonstrate the analog IC design procedure.