The product proposes a CMOS smart temperature sensor for a self-refresh controller in DRAM memory cell. The time domain temperature sensor is composed of a temperature-to pulse generator, a time-to-digital converter, and a frequency selector. The function of time measurement and feedback in the sensor is mainly performed by the delay time caused by the CMOS inverter, which has the advantage of low power dissipation and a small die area. This work proposes a CMOS smart temperature sensor in a DRAM cell that can provide a variable refresh frequency, which depends on the operating temperature. The output frequencies are obtained by the digitally controlled frequency selector in order to get low power consumption with high accuracy. A temperature-compensated current reference is applied for less temperature dependence in the CMOS delay circuits. High-performance temperature sensor is obtained with a time-to-digital converter (TDC), which is widely used for thermal and time-interval management systems.