Exar Announces New 2.5 Gbps Transceiver for SONET/SDH Applications

12/10/2002 - Exar Corporation (Nasdaq: EXAR), a leading provider of high-performance, mixed-signal silicon solutions for the worldwide communications infrastructure added another device to its SONET/SDH product portfolio. The XRT98L81 (OC-48/STM16 PHY) is a single chip solution for receiving and transmitting 2.488 Gbps SONET/SDH clock and data signals (CDR). The device also supports up to 2.666 Gbps for applications where Forward Error Correction (FEC) is required. The device contains serializer/deserializer (SerDes), clock multiplier unit (CMU), and Limiting Amplifier (LA) functions. On the system side is a four-bit, OIF SFI-4 compatible 622 MHz parallel interface. Application targets include add-drop multiplexers, cross-connect equipment, DWDM termination equipment, optical modules, ATM switches, plus multi-service switches, routers and switch/router combinations.

"The latest in a line of cost effective SONET/SDH solutions, Exar leverages its high speed, mixed signal technology to provide a wealth of new features and capabilities uniquely combined into a single-chip solution. The XRT91L81 PHY provides a dramatic improvement in system performance, board space layout requirements, cost savings and design flexibility," said Dr. Roubik Gregorian, executive VP and general manager Communications Division, CTO.

Distinguishing Features
Eliminating the need for discrete, or stand-alone limiting amplifiers, the XRT91L81 integrates this function directly onto the device. It allows for proper reception of differential signals down to 10mV-pp, which provides a greater margin for routing critical high-frequency signals. In addition, it also contains internal input bias and terminations for error-free impedance matching. Lastly, the limiting amplifiers can be capacitively coupled directly to transimpedance amplifiers, which is ideal for optical module and transponder applications.

The XRT91L81 has an auxiliary on-chip phase/frequency detector and charge pump that when combined with an external VCXO, forms a de-jittering Phase Lock Loop (PLL). It can be utilized in loop-timed applications to de-jitter the recovered received clock signal or provide clean up of a noisy system clock. Integration of this capability provides a more streamlined solution compared to the traditional use of discrete components.

Leveraging expertise in low noise, low jitter clock synthesis, the XRT91L81 generates all transmit and auxiliary reference clocks from either a standard 155.52 MHz reference clock or optionally from an even more cost effective 77.76 MHz reference clock. Clock generation includes the 2.488 GHz transmit clock, 622 MHz OIF SFI-4 compliant parallel bus clock, and an auxiliary 155.52 MHz clock for TFI-5 support. For FEC applications, the XRT91L81 will accept 83 MHz or 166 MHz references to generate the appropriate FEC rate clocks.

As with many of Exar's products this device supports both hardware mode and host mode. Hardware mode allows the configuration of the IC directly through the pins of the device. Host mode utilizes a four-bit serial interface to allow configuration via a microprocessor. In this mode, monitor and control is managed through a comprehensive register set that permits full access to all PHY functions as well as providing complete support for device status and fault monitoring. Being the only SONET/SDH PHY on the market to offer host mode operation, the XRT91L81 minimizes board space requirements and simplifies PCB signal routing. This is an especially critical advantage when used in multi-channel line-card applications.

Redundant limiting amplifier and transmitter outputs also extend the XRT91L81's use to dual fiber ring architectures.

Prices, Packages and Availability
Samples of the part are available within 30 days. The XRT91L81 in a 196-lead BGA operates at 1.8V with 3.3V I/Os over the industrial temperature range. In 1,000 piece quantities, the XRT91L81 is $80.00/unit.

About Exar
Exar Corporation (NASDAQ: EXAR) designs, develops and markets high-performance, analog and mixed-signal silicon solutions for the worldwide communications infrastructure. Leveraging its industry-proven analog design expertise, system-level knowledge and standard CMOS process technologies, Exar provides OEMs innovative, highly integrated ICs that facilitate the transport and aggregation of signals in access, metro and wide area networks. The Company's physical layer silicon solutions address transmission standards such as T/E carrier, ATM and SONET. Additionally, Exar offers ICs for both the serial communications and the video and imaging markets. The Company is based in Fremont, CA, had fiscal 2002 revenues of $55 million, and employs approximately 265 people worldwide. For more information about Exar, visit www.exar.com.

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