Abstract-A new structure for digitalk controlled oscillator (DCO) is presented in this paper. The proposed structure of DCO is implemented by standard cell libray, and with the help of C program and HSPICE simulator, the DCO can be designed in a systematic way. The DCO, which is realized on a lP4M 0.35-pm CMOS process, has a target jivquencjj at 250MHz, and it covers three process, voltage, and temperature (PVT) conditions: (FF, 3.6V, OOC), (TT, 3.3V, 25"C), and (SS, 3.0V, 100" C). The DCO, which is realized on a lP5M 0.25-pm CMOS process, has a target frequency at 400MHz, and it covers three PVT conditions: (FF, 2.75V, OOC), (TT, 2.5V, 25"C), and (SS, 2.25V, 100°C). The DCO has 32-bit control and achieves LSB resolution under Ips.