An extreme low power voltage reference generator operating with a supply voltage ranging from 0.9 to 4 V has been implemented in AMS 0.35-mum CMOS process. The maximum supply current measured at the maximum supply voltage and at 80degC is 70 nA. A temperature coefficient of 10 ppm/degC 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 2 .