A Sub-1 μs Fast-Response Buck Converter With Adaptive and Frequency-Locked Controlled Techniques

This letter proposes a new architecture of a simple and sub-1μs fast-response voltage-mode buck converter using adaptive on-time and frequency-locked controlled techniques. The adaptive on-time-controller with frequency-locked loop is employed to keep the switching frequency ( f sw ) constant at 1 MHz to achieve fixed frequency. Therefore, the switching losses, and frequency variations can be reduced to improve the converter efficiency. In addition, the proposed buck converter does not include slope compensation circuit, which will simplify the system design and shorten the transient response of the converter without adding extra acceleration circuits. Moreover, the transient response of the converter can be accelerated by choosing the appropriate equivalent-series-resistance (ESR) value for the load capacitance. The chip is fabricated in TSMC 0.35 μm 2P4M process. The experimental results show that the maximum efficiency is 90.04% when the load current is 140 mA and output voltage is 1.8 V. The load transient response time is about 0.96 and 0.94 μs when the load current changes from 100 to 500 mA and from 500 to 100 mA, respectively.