CMOS Wilson-Widlar voltage-reading temperature sensor

The paper presents the design of a CMOS integrated circuit whose output voltage varies linearly with temperature. This sensor is implemented using two classical cross-interconnected current mirrors. The circuit has a good non-linearity and occupies a small area on the chip, while its power consumption is low. The design of the sensor was done disposing of resistors with negative (NTC), null (ZTC) or positive (PTC) temperature coefficient values. We examined how the output voltage - the voltage drop on the lower Wilson mirror resistor - varies with temperature, as the output is considered to be open. The maximum slope condition for the output voltage was estimated by analytical means and this slope was computed. Then the schematic was designed to fit a maximum slope, resulting in a 4.06% error between the analytical and the simulated slope. The sensor´s performances are characterized by: the optimized output voltage slope of 4.2521mV/°C; the percentage slope of 0.255%/°C; low current consumption 30.6μA, measured at 20°C; V_DDmin=2.8V; and “Supply Regulation” SR=4.890ppm/V at 3.5V. The area that the sensor occupies on the chip is also small: 3.187μm².