1999-11-03 , E/IC-1071/46
Product News From Philips Semiconductors

Philips Semiconductors, the largest European semiconductor manufacturer, today announced a new family of laser drivers designed to overcome the poor temperature coefficient and ageing problems associated with typical laser diodes. Targeted for use in STM1/OC3 (155 Mbps), STM4/OC12 (622 Mbps), and Gigabit Ethernet (1.2 Gbps) fiber networks, all laser drivers in this new family feature two separate feedback loops for controlling the logic 0 and logic 1 optical levels in the fiber independently.

"Changes in the optical efficiency of laser diodes, caused by temperature variation and ageing, are one of the commonest causes of network degradation," said Rob Volgers, Philips Semiconductors' product marketing manager for optical fiber products. "While laser drivers with a single feedback loop only provide a partial solution, our new dual-loop laser drivers provide unsurpassed levels of stability."

The  TZA3031,  TZA3001 and  TZA3041, which are designed for 155 Mbps, 622 Mbps and 1.25 Gbps networks respectively, derive feedback from a monitor photodiode that continuously measures the optical power output of the laser. These measurements are compared against a highly stable internal band-gap reference, with the correct power levels for logical 0 and 1 in the fiber being set by two fixed resistors. Power levels in the fiber can optionally be controlled by applying two external voltage sources to the laser driver, one controlling the bias current over a 2 mA to 90 mA range, and the other controlling the modulation current between 2 mA and 60 mA.

Fabricated in an advanced BiCMOS process, all of these new laser drivers operate from a single 5 V power supply. They are available in space saving LQFP32 packages with the option of either an alarm output for signalling high and low bias current conditions, or an additional RF input for loop-back fiber testing. Naked die versions are also available with both these functions operational.

Philips Semiconductors, a division of Royal Philips Electronics, headquartered in Eindhoven, The Netherlands, is the eighth largest semiconductor supplier based on Dataquest's 1998 report^*). Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs. Additional information on Philips Semiconductors can be obtained by accessing its home page at http://www.semiconductors.philips.com

*) Based on Vendor Revenue from Shipments of Total Semiconductors Worldwide according to Dataquest's 1998 Worldwide Semiconductor Market Share report published in May, 1999.