Design of high precision ring ICO circuit with power supply voltage of 0.77V in 0.18µm CMOS process

In this study, a circuit structure of ring current controlled oscillator (ICO) is proposed. Through the cooperation of counter, bootstrap switch with special timing control and special ICO circuit module, the output frequency accuracy in traditional ring OSC is avoided from being affected by voltage range limitation and comparator delay, the temperature and voltage characteristics of output clock are improved, and the output clock with higher accuracy is obtained under low voltage and low power consumption. The test chip is manufactured by 0.18 µm CMOS process. The power supply voltage is 0.77 V, and its output frequency is 1.32 MHz. The deviation of the output clock with the power supply voltage is within ± 1%, the deviation with the temperature is within ± 2.5%, and the power consumption is 382 nW.