Widlar-Widlar total-current-reading temperature sensor

The paper presents the design of a CMOS integrated circuit whose total-current varies linearly with temperature. This temperature sensor uses two classical cross-connected current mirrors. The circuit has a simple load serial interconnection and low current consumption (25.5μA, measured at 20^oC). The design of the sensor was done using resistors with negative (NTC), null (ZTC) or positive (PTC) temperature coefficient values. We examined how the total output current varies with temperature, the maximum slope condition was estimated by analytical means and the maximum slope was computed. The schematic was designed to fit a maximum slope, thus resulting in a 4.46% error between the analytical and the simulated slope. The sensor´s performance is showed by: the optimized total-current slope of 0.1085μA/^oC; the total-current percentage slope of 0.33443·10^-6%/^oC; minimum voltage supply of 2.3V; nonlinearity of 0.78% and the area occupied on the chip is also small: 1.646μm².