No abstract

This paper presents a buck-boost dc-dc converter for LED drivers capable of delivering an output current ranging from 0.1to 2 A and a variable output voltage ranging between 2 and 5 V, starting from an input voltage spanning from 2.7 to 5.5 V. The dc-dc converter, realized in a 0.18-μm CMOS technology with 5-V option, occupies an area of 4 mm 2 including pads. The circuit features automatic mode switching and dynamic sizing of the power transistors to achieve a peak efficiency of 91%. With a switching frequency of 2.5 MHz, the achieved line regulation is lower than 0.1% V −1 and the output voltage ripple is less than 10 mV. The obtained turn-on and load transient settling time are lower than 40 μs, thus allowing pulsed operation of the LEDs, as well as switching among LEDs of different colors.

A low-power spur-free precision amplifier, which uses input chopping and correlated double sampling for demodulation, is presented. This circuit employs an AC coupling between the first and the second stage that removes the first stage offset without causing ripple. The input rail-to-rail circuit, fabricated in a mixed 0.18-0.5 m CMOS technology, operates with supply ranging from 1.8 V to 5 V. The circuit achieves a simulated 168-dB DC gain with an overall current consumption of 14.4 A. The measured offset voltage over the available samples results in a distribution with 2-V standard deviation. The obtained input noise density at low-frequency equal to 37 nV Hz gives a 5.5 noise efficiency factor.

No abstract

Design methodologies for Single-Inductor Dual-Output (SIDO) DC-DC switching converters are presented. The suitable control of a double feedback loop enables the single inductor sharing between two outputs with low output voltages errors and limited load-regulation. The design methods to achieve SIDO converters with a wide input supply voltage range and with an overall driving capability as large as 1.4 A have been verified with simulations at the transistor level. The switching frequency can be 3 MHz or more with a small off-chip inductor.