This paper deals with time drift problems of polysilicon resistors used as heater in gas sensors. Actually, this polysilicon heater is applied by a constant voltage, so its time drift about 20% of nominal value implies an equivalent variation of operating temperature. Then, this study presents a new design of power-control unit dedicated to force the same power on the heater resistor independently of its value and its time drift. Elaborated with two current mirrors, a multiplier and a proportional regulation system, this non optimized prototype allows good temperature stabilization with an error which doesn't exceed 3°C in the worst case.