A monolithic buck converter using differentially enhanced duty ripple control

This paper reports a monolithic DC-DC buck converter using the differentially enhanced duty ripple control (DE-DRC). Without any compensation circuit, this converter is stable over a wide input and output range. The switching frequency is kept constant by adjusting the on-time according to the input and output voltage. Because of the large duty ripple voltage with a big noise margin, the DE-DRC buck converter has better noise immunity than current mode and hysteretic control. The easily configured positive and negative differential difference amplifier (DDA) gains (K_p and K_n) can adjust the high and low frequency portion of the loop transfer function to achieve fast load transient response. Load transient test also showed 5 mOmega pure resistive output impedance of this converter to achieve the adaptive voltage position (AVP) function. We demonstrated a 1.85 MHz single phase converter with wide conversion range of 10%-86.6%. This circuit was implemented in 0.5 mum BCD process of TI.