A 4-MHz Ultra-Fast Transient Response Capacitor Current Adaptive On-Time (CCAOT) Controlled Buck Converter with Passive Ramp Compensation
Journal
2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia
ISBN
9784886864253
Date Issued
2022-01-01
Author(s)
Abstract
This paper proposes a monolithic capacitor current mode adaptive on-time (CCAOT) controlled buck converter. A capacitor current-controlled modulation scheme ensures an ultra-fast load transient response but suffers from sensing circuit mismatch-induced instability. A concise passive ramp is employed to mitigate the problem. Moreover, a V2-loop eliminates the circuit delay caused on-time pulse error and achieves a pseudo constant frequency. Implemented in a 0.18µm CMOS process with a 4-MHz high switching frequency, this circuit occupies an area of 1189 µm * 1199 µm with pad ring. The experiment results guarantee a fast load transient response during a 1A/500ns load transient. The converter can regulate the output voltage within 1 µs with only 42 mV undershoot while the output capacitor is only 1.8 µF. The switching frequency is varied only 2% with 1A loading current changed. Besides, there is no instability concern, unlike priors.
Subjects
capacitor current adaptive on-time (CCAOT) control | dynamic on-time generator | fast load transient response | V2 constant on-time control | voltage regulator module (VRM)
Type
conference paper