VARIABLE AMPLITUDE WIDTH MODULATED DRIVING APPROACH SUITABLE FOR USE IN HIGH-COLOR-PRECISION OF LEDs

A bi-level approach has been proposed to reduce energy wastage while running a different set of LEDs string. The method is driven based on two parameters, which are low/high current levels (PWM-based) that associated with duty cycles, to have the capability of controlling luminosity. The approach has improved the LED's luminous efficacy accordingly. However, it comes with the trade-off of losing efficiency with resistors' introduction for creating a bi-level phenomenon. Thus, in this paper, a new approach of driving RGB LEDs that replacing the resistors with novel dimming circuits is proposed. The new approach offers the hybridization of pulse width modulated (PWM) and amplitude modulated (AM) to get variable amplitude width modulated driving. It has shown a significant improvement for the overall system's efficiency with the ability to dim an individual LED of any designated color (red, green, or blue) that suits the various applications in LED display panels. The circuit simulation environment has been carried out to verify the approach. The findings have been observed that with the 0.2 V of PWM signal strength, the LEDs can be controlled with a single dc-dc converter for three different LED strings. With neglected string wire resistances losses, the yield computed efficiency is in the range of 92% to 99%.