DC-DC Voltage Conversion

As seen in previous chapters, use of the appropriate voltage for the performance required is one of the most powerful techniques for improving energy efficiency. This can be either done statically by choosing the single most appropriate voltage for the throughput required or dynamically by using information obtained by the operating system and applications. This chapter introduces switching regulators which allow translations of DC voltages with efficiencies of over 90%. Design equations and closed-form expressions for losses are presented for the three basic low-voltage CMOS switching regulator topologies — buck, boost, and buck-boost — controlled via pulse-width or pulse-frequency modulation. This then will be followed for the enhancements to the basic design that are required for efficient dynamic voltage regulation.