Digitally assisted discontinuous conduction mode 5V/100MHz and 10V/45MHz DC-DC boost converters with integrated Schottky diodes in standard 0.13µm CMOS

Abstract

On-chip or on-package integration of step-up DC-DC converters in a low-voltage process can be attractive for smaller and lighter portable devices powered from single-cell batteries (i.e., NiMH, Fuel cells). To reduce the size of the off-chip components both high frequency (10 to 100s of MHz) [1, 2] and discontinuous-conduction-mode (DCM) switching have been proposed [3]. However, integration of DCM converters is challenging when the required blocking voltages across the switch and rectification stage is higher than the breakdown voltage of the standard devices. This is the case in both diode-connected MOS or CMOS controlled rectifiers for DCM boost converters [3]. Moreover, adaptive dead-time controllers are required for high-efficiency DCM operation. In this paper, we report two high-frequency DCM boost converter topologies with integrated Schottky Barrier Diodes (SBD) and a high voltage synchronous switch in a standard 0.13µm CMOS process. The SBDs are fabricated without additional processing steps to sustain ˜10V reverse voltage for high voltage operation, eliminating the need for dead-time controllers and power hungry high side drivers. The first DC-DC converter is a 100MHz digitally assisted 4-phase boost converter that delivers 240mW from a 1.2V supply with an output voltage range of 3 to 5V; and the second is a 45MHz hybrid boost converter delivering 20mW at 6-to-10V output from a 1.2V supply.