Low-voltage subthreshold CMOS current mode circuits: Design and applications

The world has migrated to portable applications ranging from smart phones to Lab on a Chip applications. However they come with a new set of challenges for analog IC designers. Low voltage operation, small area and low noise are the critical design criteria for portable devices. This paper presents a gm/ID based design methodology for low voltage current mode circuits using standard CMOS technology. A second generation current conveyor (CCII) and a current feedback operational amplifier (CFA) are designed using the discussed design procedure. Both circuits operate from a single 0.4 V supply. The CCII is used to implement an instrumentation amplifier. Multiple applications are implemented using the CFA. Post layout simulation using TSMC 90 nm and UMC 130 nm technology show that the presented design procedure is an attractive solution for low voltage CMOS current mode circuits.