This paper proposes a low power CMOS smart temperature sensor which is composed of temperature-to-current generator (TCG), analog-to-digital converter (ADC), and frequency selector. The multiple-block system is to obtain the self-refresh operation for a low power memory cell. The current references and cascode structure are applied in TCG. In frequency selector, oscillator and frequency divider are used to obtain 10 output signals through decoder. The small-size voltage-mode temperature sensor is designed with 0.35-μm CMOS process. Ten different digital outputs are obtained for the temperature ranges of -30 ~ 80 °C. Simulation test shows that the proposed temperature sensor is operated with power dissipation of 8.28 mW per sample.