New millennium ultralow power microsystems

Mixed-signal electronics form the core of spacecraft avionics systems. Low-power operation is a key design objective to reduce dependence on stored energy or energy extraction systems. To facilitate low-power operation. The supply voltage of mixed-signal systems has progressively diminished to typical present values of 3.5 V to 3.6 V. Low voltage design, however, increases susceptibility to noise interference and reduces the range of analog linear gain. Moreover, as transistor density and circuit complexity increase, traditional power minimization methods are inadequate. In this paper we present results of several approaches to enable low-power mixed-signal electronics for spacecraft avionics and commercial telecommunications. First, at the architectural level we analyze a dynamic voltage scaling approach that delivers local isolation of bus noise and a power reduction of 50% to 95%. Next, to enable in-situ, real-time power sensing we introduce two sensors that monitor di/dt and dv/dt events. Their design, scaling, and sensitivity are discussed in detail. Finally, as an example of a low-voltage compatible analog circuit we present results of a low-noise differential analog-to-digital comparator. It operates at speeds to over 50 MHz, has per-comparator power dissipation under 1 mW, and can operate at supply voltages down to 1.9 V. All circuits have been designed and analyzed for a 0.5-/spl mu/m CMOS, and analytical and experimental results are given.