Abstract: Based on TSMC 65 nm CMOS process, a fully-integrated KY boost converter with high efficiency and fast response is designed. Aiming at the problem of low light-load efficiency and slow transient response of pulse width modulation (PWM), a variable frequency control strategy named adaptive constant on/off time with transient enhancement is proposed. The strategy adopts adaptive time control technology, which can automatically adjust the timing according to input voltage, output voltage and load current, and optimizes the output voltage ripple. At the same time, a transient enhancement circuit is designed. When the output is as low as the voltage limiting threshold, the charging time of timers is extended, which accelerates the system recovery. In addition, a DCM self-calibration circuit is designed to achieve accurate zero-crossing turn-off. The simulation results show that the load ranges from 0 to 120 mA and the peak efficiency is 71.5% under the typical application of 1.5 V input voltage and 1.8 V output voltage. At 10 mA light load, the efficiency is still 52.4%. When the load transients at a step height of 110 mA, the response speed of the system is 2.55 ns/mA and 6.18 ns/mA, respectively.tively.