Ultra-fast on-chip load-current adaptive linear regulator for switch mode power supply load transient enhancement

A fully on-chip linear regulator is presented in this paper to enhance the load transient response in a switch mode power supply (SMPS). Different from the conventional linear regulator, it employs a push-pull output structure, allowing both step-up and step-down transient current compensation. A multi-level self-biased controller is designed to adaptively compensate the instantaneous current difference between the SMPS and the load, achieving ultra-fast and smooth load transient response. An IC prototype is designed and fabricated with a standard 0.35µm digital CMOS process. 40.3ns load transient response time is achieved for a 100-mA load step change. In addition, it is also capable of dynamic voltage scaling (DVS), with a measured tracking speed of about 1 V/µs.