A Hysteresis-Controlled Buck Converter with Active Pseudo-Current and Frequency-Locked Techniques

The paper presents a hysteresis-controlled buck converter with active pseudo-current and frequency-locked techniques. The hysteresis-controlled method accelerates the transient response in the load variation. The proposed buck converter uses phase-frequency locked technique to solve the variable switching frequency and electromagnetic disturbance problems. Therefore, the frequency-locked circuit is used to fix the switching frequency. The stable output voltage is important, when the input or output voltage is changed. This condition can be benefited by the current sensing loop, and the active pseudo-current-sensing technique can greatly improve transient responses. This chip has been fabricated in TSMC 0.35µm CMOS process and the output voltage range is from 1V to 2.5V. The maximum load current is 600mA. The minimum recovery time is 2µs when the load current range is from 50mA to 500mA. In all condition, the switching frequency can be fixed in 1MHz. The chip area is 1.5 mm × 1.5 mm.