The influence of parasitic substrate diodes on load transient response of three-terminal adjustable voltage regulators

This paper presents a detailed analysis of the influence of parasitic substrate diodes on the load transient response of three-terminal adjustable voltage regulators with the substrate connected to the output. Two simple solutions for improving the transient behaviour are then presented. A 1A voltage regulator was implemented in a single metal layer BCD technology. Using no additional chip area, the undershoot has been reduced from 250mV to less than 30mV, for an output voltage of 5V. The duration of the undershoot is accordingly reduced.