Electronic Design

Low-Power Equalizer/Driver Simplifies 10-Gbit/s Optical Links

Before you can transmit data at 10 Gbits/s over any optical or copper cable, you need equalization and careful retiming— and the Phyworks PHY1066 equalizer/driver/retimer IC provides these qualities (see the figure). It’s designed for use in 10-Gbit/s Ethernet SFP+ modules for direct attachment to passive twin-ax copper cables (up to 15 m long) and 10GBaseSR optical modules. Also, it uses programmable preemphasis with feed-forward equalization (FFE) or decision feedback equalization (DFE) algorithms.

The PHY1066’s retimer ensures clean data regardless of cable thickness, reach, or interference conditions. Its loss of signal and loss of lock alarms connect to the host controller by two-wire serial peripheral interface (SPI) connections. The IC’s pseudorandom bit sequence (PRBS) and biterror rate test (BERT) functions make it easy to set up and implement test conditions. A reference design is available, and the chip is sampling now. Pricing is expected to be less than $10 in volume.

Additionally, the XFP 10GEPON Demonstrator board illustrates the use of Phyworks chips in passive optical network (PON) customer premises units. Manufacturers of fiber to the X (FTTX) systems and optical modules now have a way to see how Phyworks chips perform in 10G PON systems—specifically systems based on the IEEE 802.3av standard, which is expected to be ratified in August 2009.

The Demonstrator supports an upstream rate of 10 Gbits/s and a 1.25-Gbit/s burst mode downstream. The unit uses Phyworks’ PHY1090 high-sensitivity transimpedance amplifier with the PHY1060 integrated post amplifier, equalizer, and retimer. The transmit path uses the PHY2078 1.25-Gbit/s burst mode laser driver, which allows the use of a higher-power distributed feedback (DFB) laser.

Phyworks Ltd.

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