A Sub - 1 - V , 10 ppm / C ,

An extreme low power voltage reference generator operating with a supply voltage ranging from 0.9 to 4 V has been implemented in AMS 0.35m CMOS process. The maximum supply current measured at the maximum supply voltage and at 80 C is 70 nA. A temperature coefficient of 10 ppm C is achieved as the combined effect of 1) a perfect suppression of the temperature dependence of mobility; 2) the compensation of the channel length modulation effect on the temperature coefficient; and 3) the absence of the body effect. The power supply rejection ratio without any filtering capacitor at 100 Hz and 10 MHz is lower than 53 and 42 dB, respectively. The occupied chip area is 0.045 mm .