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Chips rev up GPON systems

Posted: 19 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:triple-play services? Gigabit passive optical network? Ethernet PON? GPON chip?

With an eye toward cost reduction and providing triple-play services in a bandwidth-efficient manner, service providers are turning to Gigabit passive optical network (GPON) systems over Ethernet PON to transport 2.5Gbps converged data and voice services in the last mile.

Interface chip makers serving the sector are taking note of the move. Ethernet PON delivers only 50 percent of usable bandwidth to the service providerinsufficient to support legacy TDM and voice. In addition, EPON supports only Optical Distribution Network (ODN) Classes A and B, while GPON also supports ODN Class C, increasingly required by service providers all over the world.

SoC from BroadLight
From transceivers to switches, the interface chip market is becoming copious with parts. BroadLight Inc. appears to be leading the charge. In June, the U.S.-based company made two key GPON chip announcements. By year's end, it plans to sample the BL2348 GPON residential gateway (RG) SoC for fiber-to-the-home (FTTH) applications, as well as the BL2347 GPON optical-network-termination SoC, targeted at lowering the cost of residential ONTs.

According to BroadLight, BL2348 provides the performance, integration and functions needed by the new breed of cost-effective broadband residential gateway customer-premises equipment (CPE) connecting the high-speed digital home to FTTH services. BL2348 leverages BroadLight's PONRunner network processor in a dual-core architecture to perform the necessary Layer 2, 3 and 4 packet functions with 1Gbps throughput.

BL2348 embeds a GPON MAC, as well as a VoIP DSP for four concurrent ports, three-way calling and T.38 fax. GateMaker software is offered for gateway functions of firewall, security, SIP, management, QoS and NAT. The chip includes standard interfaces for home-networking technologies such as Gigabit and Fast Ethernet, 802.11 a/b/g/n, MoCA, HomePNA, Home-Plug and USB.

The BL2347 chip extends BroadLight's product coverage for all ONT types by integrating voice and Ethernet switching features. BL2347 integrates a VoIP DSP and a four-port Ethernet switch and provides a throughput performance of 1Gbps for any packet size on its GbE port.

With GPON MAC and PONMaker software, BL2347 offers ONT equipment vendors a fast path to market with the assurance of interoperability with any ITU-T G.984 compliant optical line terminal (OLT), BroadLight said.

By year's end, BroadLight plans to sample the BL2348 GPON residential gateway SoC for fiber-to-the-home applications.

BroadLight also launched a quad GPON controller that's said to provide the industry's highest integration for packet and TDM transport over ITU-T G.984 GPON while slashing power, space and cost requirements for multiport OLTs. The BL3458 is built on the single-port BL3238 GPON OLT MAC and includes an embedded processor for acceleration of dynamic bandwidth allocation.

Ethernet switches debut
Fulcrum Microsystems is aiming two Ethernet switches at multiport OLT cards for GPON equipment. The FM2103 and FM2104 devices are designed to smooth the migration path from single- to multiport interfaces in OLT cards.

FM2103 is configured for four-port OLT cards with four 2.5GbE ports for access connections and two 10GbE Xaui ports for backbone links. FM2104 is for eight-port OLT boards and features eight 2.5GbE ports with two 10GbE Xaui ports. Both devices feature flexible header processing for Ethernet-to-GPON networking, allowing the FM2103 and FM2104 to parse the GPON-specific packet header.

The FM2103 and FM2104 switches join Fulcrum's FocalPoint family of devices, all of which are based on shared memory architecture. While the shared memory architecture concept is not new, "the whole design flow is a proprietary process. It does use that event-driven logic, which provides a very fast data path, but also has an unusual principle of operation in that it does not dissipate energy unless data is flowing through it," said Bud Noren, senior product manager at Fulcrum.

The FM2103 and FM2104 have typical power dissipation of less than 10W and 9W, respectively. When they are functioning at the 10Gbit mode, they dissipate about 1W/port.

Multiple options
Maxim Integrated Products offers a highly integrated optical control, calibration and monitor IC. DS1865 integrates GPON power-leveling functionality, a laser bias average-power-control loop, video-amp control and SFF-8472 diagnostic and alarm features. Those capabilities are said to suit the DS1865 for all BPON and GPON triplexer applications.

The DS1865 controller is optimized to work with the MAX3643 burst-mode laser driver for a compact GPON system solution. By implementing all control, monitoring and fault management functions in CMOS, the total solution cost for a GPON transceiver is reduced, according to Maxim.

Micrel Inc.'s SY87725L programmable Serdes chip supports multiple PON standards and rates, including asymmetric GPON with data rates up to 2.5Gbps on the receive side and 1.25Gbps on transmit.

The device offers clock recovery and data-retiming circuitry, along with an integrated 4bit serial-to-parallel data converter, on the receive side. On the transmit side, it adds a synthesizer with an integrated 4bit parallel-to-serial data converter. It targets the FTTH and fiber-to-the-premises (FTTP) markets.

Conexant Systems Inc. is shipping SoCs for GPON and GEPON residential gateway apps. The CX95202 Xenon-IIIG GPON and Xenon-IIIE GEPON devices target ONUs used on the client side of FTTP nets. Processing capacity exceeds10Gbps.

-EE Times

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