An integrated direct-coupled 10-Gb/s driver for common-cathode VCSELs

An all- npn integrated driver for directly modulating common-cathode vertical-cavity surface-emitting lasers (VCSELs) at high speeds (such as 10 Gb/s) is proposed and experimentally demonstrated. Special biasing techniques allow the output transistors to operate with small collector-emitter voltages while maintaining their fast current-switching capabilities. A current-splitting technique in the output stage minimizes the transients through the bias source and reduces jitter and overshoot.