Fixed-frequency hysteretic buck converter with novel adaptive window control and transient response improvement

Abstract

This study presents a fixed-frequency hysteretic buck converter designed and fabricated using 0.18-µm complementary metal–oxide–semiconductor process. With a phase-locked loop (PLL)-based adaptive window control, the proposed buck converter can achieve a fixed switching frequency, and this frequency can be tuned within a certain range through a reference clock frequency. Concurrently, a novel auxiliary circuit is proposed to monitor the converter's output loading dynamics to reduce the converter's transient recovery time. It will also help to regulate the output voltage at the steady-state operation as well. With the supply voltage ranging from 3 to 4.2 V and an output voltage of 1.8 V, the simulated switching frequency is maintained at 10 MHz because of the PLL control. The transient response time is only 0.3 and 0.4 µs for a 400 mA step-up load and step-down load, respectively.

Keywords

• CMOS integrated circuits
• switching convertors
• phase locked loops
• transient response
• adaptive control
• voltage control
• clocks
• phase-locked loop-based adaptive window control
• fixed switching frequency
• reference clock frequency
• output voltage
• simulated switching frequency
• fixed-frequency hysteretic buck converter
• novel adaptive window control
• transient response improvement
• complementary metal–oxide–semiconductor process
• auxiliary circuit
• converter output loading dynamic monitoring
• output voltage regulation
• steady-state operation
• converter transient response time
• PLL control
• voltage 3.0 V to 4.2 V
• time 0.3 mus
• time 0.4 mus
• voltage 1.8 V
• frequency 10.0 MHz
• current 400.0 mA
• size 0.18 mum