A combined low-
voltage, low-
power band-gap reference and temperature sensor circuit is provided for providing a band-gap reference parameter and for sensing the temperature of a
chip, such as an
eDRAM memory unit or CPU
chip, using the band-gap reference parameter. The combined sensor circuit is insensitive to supply
voltage and a variation in the
chip temperature. The
power consumption of both circuits, i.e., the band-gap reference and the temperature sensor circuits, encompassing the combined sensor circuit is less than one μW. The combined sensor circuit can be used to monitor local or global chip temperature. The result can be used to (1) regulate
DRAM array
refresh cycle time, e.g., the higher the temperature, the shorter the
refresh cycle time, (2) to activate an on-chip or off-chip cooling or heating device to regulate the chip temperature, (3) to adjust internally generated
voltage level, and (4) to adjust the CPU (or
microprocessor)
clock rate, i.e., frequency, so that the chip will not overheat. The combined band-gap reference and temperature sensor circuit of the present invention can be implemented within battery-operated devices having at least one memory unit. The low-
power circuits of the sensor circuit extend battery lifetime and
data retention time of the cells of the at least one memory unit.