A 65-nm, 1-A Buck Converter With Multi-Function SAR-ADC-Based CCM/PSK Digital Control Loop

Abstract

This paper proposes a 1-A, 6.4-MHz switching frequency DC-DC converter with embedded digital controller, implemented in 65-nm CMOS technology. The proposed DC-DC converter, exploiting a customized, multi-function SAR ADC and a non-linear PID controller, can switch automatically between continuous-conduction mode and pulse-skipping mode, thus maintaining a fairly large efficiency also for light loads. Moreover, a feedforward path in the digital control loop, implemented using the SAR ADC for converting also the battery voltage, significantly improves the line transient performance. The DC-DC converter, which occupies an area of 0.038 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , consumes 115.5 μA, and requires an external inductance as low as 470 nH, is particularly suited for portable applications.