Undershoot suppression technique for fully integrated pulse-width modulated switching converters

A shunt-regulation control technique is presented to improve the load transient performance of fully integrated high-frequency converters. The undershoot voltage, which used to be limited by the system loop response and the nanofarad range small on-chip capacitor, is significantly suppressed. The proposed converter is simulated by a standard 0.13 μm CMOS process using a 6 nH inductor and 10 nF capacitor under different process corners with parasitics extracted from the layout of critical blocks. Compared to a conventional converter with the bandwidth pushed to the limit, the undershoot voltage is reduced from 360 to 100 mV with a transient step of 150-550 mA in 100 ps.