Design and realisation of high-speed transmitter arrays based on CMOS integrated drivers and resonant cavity LEDs

Parallel optical interconnects between chips need compact, high-speed, reliable, cheap and efficient components. RCLEDs have been proposed as a light source in such links. Standard drivers for interconnects consist of a switched current source. However, this switching results in slow responses, especially at low current densities. It was found that the current driven RCLEDs need a very large current density to achieve the desired operation speed. This is incompatible with the power budget constraints. Voltage driven RCLEDs had shorter rise and fall times compared to the current driven RCLEDs, which is explained by the peaked current, which fills up the active layer much faster compared to the current driven RCLEDs. In this paper, three different driver designs based on this current peaking principle will be presented. The key feature of the drivers is their ability to generate a peaked current pulse, both at the on-switching and off-switching.