A 4-MHz Ultra-Fast Transient Response Capacitor Current Adaptive On-Time (CCAOT) Controlled Buck Converter with Passive Ramp Compensation
Journal
IEEE Transactions on Industry Applications
Date Issued
2023-01-01
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. However, this scheme suffers from sensing circuit mismatch-induced instability, hence a concise passive ramp is proposed to mitigate the problem. The small signal model of the scheme is established to demonstrate the design standard of the system parameters. 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 a total area of 1189 μm by 1199 μm in width and length including the pad ring. Finally, the experiment results show a fast load transient response, which is 42mV voltage drop and 1μs response time under the conditions of 1.1V output voltage and 1A load step-up with 1A/500ns slew rate. In addition, the frequency variation is 2% for a 1A load step and there is no instability issue in this work.
Subjects
Buck converters | capacitor current adaptive on-time (CCAOT) control | capacitor current-controlled modulation | Capacitors | dynamic on-time generator | fast load transient response | Inductors | Modulation | Oscillators | Sensors | Transient response | voltage regulator module (VRM)
SDGs
Type
journal article