Francesco Pulvirenti

4-Phase Interleaved Boost Converter With IC Controller for Distributed Photovoltaic Systems

We present a DC-DC converter for photovoltaic (PV) applications that is suitable for distributed power conversion obtained by transferring part of the electronics from the inverter to the module. The proposed circuit implements a high-efficiency four-phase interleaved boost converter employing relatively low-valued inductive and capacitive components. Its compact realization is made possible thanks to the innovative design of a dedicated integrated circuit (IC) embedding the power MOS switches and performing the converter control section as well as the Maximum Power Point Tracking (MPPT) algorithm. The solution is designed for a maximum delivered power of 300 W and to work with an MPPT voltage between 9 V and 36 V, with maximum allowed panel current of 9 A. The area of the complete printed-circuit board is 4 cm × 7 cm. Experimental measurements show that the average power conversion efficiency is between 93% and 99% and that the MPPT efficiency is always greater than 99.7%.

670-nA CMOS OTA FOR AMLCD COLUMN DRIVER

A transconductance operational amplifier specifically optimized for a switched-capacitor LCD column driver is presented. It exploits MOS transistors in subthreshold region and dissipates 670 nA at DC. Despite this extremely low quiescent current value, the amplifier exhibits a DC gain of about 80 dB, and a gain-bandwidth product and phase margin around 2 MHz and 70°, with a load capacitance of 500 fF. Besides, working in class AB, the solution provides a slew rate equal to 27 V/μs. With exception of the DC gain, these performances represent an improvement with respect to comparable solutions, and are obtained while halving the area occupation.

Low voltage-drop bypass switch for photovoltaic applications

We describe an active circuit that can be used as a low-voltage bypass element and that can profitably replace the Schottky diodes in photovoltaic (PV) panels. The proposed solution is made up of a power MOS device with its embedded driving circuitry. The whole circuit does not require a dedicated DC power and is fully compatible with standard CMOS technologies. A prototype is fabricated and experimentally characterized. Compared to conventional Schottky diodes the power dissipation is reduced by more than 70%. Due to its simplicity, the solution can be integrated even directly on the panel.

Low quiescent current high speed amplifier for LCD column driver

The design of a very low-current transconductance operational amplifier specifically optimized for a switched-capacitor LCD column driver is presented. Despite its stringent standby current requirements (lower than 700 nA), the amplifier exhibits a DC gain of about 80 dB and, working in class AB, provides a slew rate greater than 20 V/mus under a load capacitance of 500 fF. The gain-bandwidth product and phase margin are about 2 MHz and 70deg. With exception of the DC gain, these performances represent a major improvement with respect to comparable solutions, and are obtained while halving the area occupation.