A high frequency active voltage doubler in standard CMOS using offset-controlled comparators for inductive power...

Area of Science:

• Electrical Engineering
• Microelectronics
• Power Electronics

Background:

• Inductive power transmission is crucial for implantable microelectronic devices (IMD) and radio-frequency identification (RFID) tags.
• Existing solutions face limitations in range, efficiency, and input voltage requirements, especially with weakly coupled inductive links.

Purpose of the Study:

• To present a fully integrated active voltage doubler using offset-controlled high-speed comparators.
• To enhance the power conversion efficiency (PCE) and extend the operational range of inductive power transmission systems.

Main Methods:

• Developed an active voltage doubler in 0.5-μm CMOS technology.
• Utilized offset-controlled comparators to manage turn-on/off delays and optimize charging/back currents.
• Integrated a start-up circuit for low-voltage operation.

Main Results:

• Achieved the highest reported PCE of 79% at 13.56 MHz with a 1.46 V peak AC input.
• Provided a 2.4 V DC output across a 1 kΩ load.
• Demonstrated higher PCE and lower dropout voltage compared to passive counterparts.

Conclusions:

• The active voltage doubler offers a reliable and efficient solution for inductive power transfer to IMDs and RFID tags.
• Offset-controlled comparators are key to optimizing PCE in the high-frequency band.
• The design enables efficient operation even with weakly coupled inductive links and lower input voltages.