An Ultrafast Load Transient Response Double Capacitor Current Ramp Integrating Constant On-Time (DCCRICOT) Controlled Buck Converter

With the rapid advancement of artificial intelligence (AI) in mobile devices, power supply requirements such as fast transient response and high light-load efficiency for processors are increasingly critical. In this article, a double capacitor current ramp integrating constant on-time (DCCRICOT) control is proposed to achieve an ultrafast load transient response and a high noise immunity over other control schemes. Conventional control schemes with capacitor current sensing ensure an ultra-fast load transient response but suffer from sensing circuit mismatch-induced instability. Hence, a double capacitor current ramp integrating scheme is proposed to provide stable operation without sacrificing load transient response. Moreover, this scheme improves noise immunity, providing accurate triggers in both continuous-conduction mode (CCM) and discontinuous-conduction mode (DCM). Implemented in a 0.18 μm CMOS process, this chip size is 1289 μm by 1199 μm. Experimental results demonstrate a fast load transient response with a 62 mV near optimal output voltage drop (deviation-from-ideal rate is only 1.9%) and a 1.6 μs response time without any instability issue under conditions of a 1.1A load step-up with a 1.1 A/70 ns slew rate.