Phyworks eliminates external sample-and-hold circuitry for transceiver chip

MARCH 26, 2009 -- The IC developer's GEPON module design gets a transmit power monitor to reduce network maintenance and downtime.

MARCH 26, 2009 -- Phyworks (search Lightwave for Phyworks) has enhanced its reference design for FTTX GEPON modules, with the addition of transmit power monitoring to its digital diagnostics and set-up facilities. Now being specified by China's network operators, the monitoring of laser output power aims to streamline field maintenance procedures and substantially reduce equipment downtime.

Based around either Phyworks' PHY1078 or PHY2078 burst-mode transceiver, the reference design uses a simple external monitoring circuit in conjunction with new microcontroller firmware, GUI, and the transceiver's internal digital bias-control loop to provide real-time measurement and display of transmit power.

Supporting the design of SFF-8472 standard compliant GEPON modules, the reference design also provides shutdown protection in the event of a transmission fault. If an alarm is triggered, the monitor circuit completely disables the laser to prevent a faulty optical network module from blocking other users on the network.

By virtue of the transceiver chip's internal digital bias control loop, the company says its device avoids the need for the costly external sample-and-hold circuit required by other transceiver chips. In addition, the internal digital sampling avoids switched external capacitors and improves power measurement accuracy compared with more complex circuits, according to Phyworks.

Phyworks is supporting the new reference design with a full complement of schematics, bill of materials, firmware, and evaluation boards.

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