General Description
The VSC7990 is a single +5V or −5.2V supply, 10.7Gb/s laser diode driver with direct access to the laser modulation and bias FETs. Laser bias and modulation currents are set by external components allowing precision monitoring and setting of the current levels. Clock and data inputs are differentially terminated to 50Ω and must be AC-coupled. The superlative edge-rate and drive current of the VSC7990 enables efficient design of an OC-192/STM-64 transmitter using directly modulated laser diodes. A two-chip OC-12 to OC-192 optical transmitter can be easily implemented using the VSC7990 and the VSC8171 10Gb/s MUX/CRU.

FEATUREs
• 100mA Available Modulation Current
• 100mA Available Bias Current
• 10.7Gb/s Operation
• Duty Cycle Control
• Single Power Supply
• Direct Access to Modulation and Bias FETs
• On-chip Reclocking Register
• On-chip MUX for Selectable Clocked or Unclocked Applications
• On-chip 50Ω Input Termination for Clock and Data
• Available in Tested Bare Die

APPLICATIONs
• OC-192/STM-64 @ 2.488Gb/s to 10.7Gb/s
• 10Gb/s Serial Ethernet