Technology for the design of low-power circuits

Operation of integrated circuits at micropower levels requires transistors with adequate current gain at collector currents of 1 /spl mu/A and less and resistors of the order of 1 M/spl Omega/ within reasonable areas. Factors affecting current gain at low currents are discussed and design criteria presented that optimize gain at low collector current. A benefit of micropower operation is low-current noise. Factors tending to optimize noise performance are discussed. In order to obtain voltage gain at low collector current, high values of load resistance are required. Both passive and active loads suitable for incorporation in micropower integrated circuits are discussed.