• Communications


    With over 40 years of mixed-signal design expertise, world-class product reliability and field support, Exar stays focused on leveraging its strengths to solve your design challenges. Innovative and leading edge design techniques are applied throughout Exar's T/E/J and SONET/SDH product portfolio. Exar's ASSPs focus on the Transport infrastructure required by today's Telecom and Communications Service Providers.

  • PDH

    Exar has a comprehensive and broad T/E/J physical layer product portfolio: Line Interface Units (LIUs), Analog Front Ends (AFEs), framers, LIU/ framer combos, LIU/Jitter Attenuator Combos (with and without Desynchronization), BITS clock receivers and transceivers, and PCM line interfaces. Our products provide bridging solutions from existing networks to EoPDH, Circuit Emulation (CES) and Pseudo Wire (PWE) applications as well as providing synchronization for Ethernet networks through our BITS solutions. Exar has a history of innovation with many industry firsts:

    • R³ Technology™ (Reconfigurable, Relayless Redundancy)
    • An 8-Channel integrated LIU/Framer device, replaces several discrete components
    • Up to 14-Channel long/short haul T1 LIU, (21-Channel for E1)
    • A 28-Channel T1/E1 LIU/Framer with VT/TU Mapper and M13 Multiplexer
    • Up to 12-Channel T3/E3 LIU

    PDH Framer and LIU Solutions

    Exar has a great reputation for offering innovative T1/E1/J1 as well as T3/E3/STS-1 products with many industry firsts, including the single-chip Jitter Attenuators (JA), integrated LIU with JA and CDR (Clock and Data recovery), and an integrated LIU plus SONET/SDH desynchronizer. The LIU function incorporates the R³ (Relayless, Reconfigurable Redundancy) Technology™ for minimal footprint and cost effective solutions. Exar is well known for outstanding product reliability and design support over a wide range of devices. Used individually or in chipsets, these devices are used in systems for many of the leading networking equipment manufacturers.

    Another family of Framer / Mapper products provide flexible mapping of multi-channel T1/E1 clients into SONET/SDH networks. The highest density product in this family provides mapping of 28 independent T1s (or 21 E1s) into an STS-1. It also supports the transparent transfer and regeneration of the independent T1/E1 clocks across the SONET/SDH network and meets all the jitter / wanders specs of the T1/E1 client interfaces.

    Exar PDH Technology Advantages

    Exar offers many advantages to system designers. Key among these are features that provide flexibility in design, enable system reliability, reduce cost, and provide standards compliant solutions.

    R³ Technology™

    R³ Technology™ means Reconfigurable, Relayless Redundancy. Designers can configure or reconfigure a card (board) in software without changing any external components.

    • • Reduces time-to-market/manufacturing costs
    • • Allows single Bill-of-Material (BOM) for worldwide applications


    Employing a full suite of loop-backs, Exar devices can quickly identify a fault location, invoke a complete set of alarms, and easily determine the fault type for the network operator. This detection and diagnostic capability is critical to reliable data transmission. Exar's PDH products have the several client and facility side loop-backs for each function providing designers with a built-in diagnostic solution for the physical layer. A suite of Performance Monitoring (PMON) counters keep track of the integrity of each of section of the links.


    All of Exar's T/E Carrier and DS3/E3 products are industrial grade with a temperature of -40ºC to +85ºC.

    Innovative Features

    Redundancy Internal switches help to implement 1:1 or 1+1 redundancy without the need for any relays, which helps to reduce cost and board space while improving reliability.

    Hot Swapping Exar's LIUs not only support 1:1 or 1+1 redundancy, but also support hot swapping without relays.

    Integrated Timing Generators An on-board timing circuit generates the appropriate system clocks from a single crystal. This again eliminates the need to change any components externally.

    Design Flexibility Choice of Host (software) or Hardware mode for interfacing and control provide design flexibility.

    Extensive Diagnostic Capability System users can quickly isolate a fault location, use alarms, and determine the nature of the fault.

    Applications of T1/E1/J1 and T3/E3/STS-1 products

    Exar's world-class physical layer solutions are ideal for a wide variety of markets and applications:

    • BITS (T1/E1)
    • Digital Cross Connects
    • Access Concentrators
    • Multi-Service Provisioning Platforms (MSPP)
    • ATM and Frame Relay Switches
    • Routers
    • Wireless Base Stations
    • DSLAMs



    Why Exar?

    EXAR has highly integrated multi-channel SONET/SDH framer products with on chip high speed multi-channel SERDES functions, a range SONET/SDH CDR and Transceiver products. The higher levels of integration and superior jitter performance has benefited many successful SONET/SDH product deployments.

    Higher Levels of Integration and Functionality

    At the high end, the highest density devices contain 16xOC-48/STM16 or 4xOC192/STM64 framers with 768 Pointer Processors plus 32x2.5G high performance analog SERDES with CDR functions that drive SFPs and meet all SONET/SDH jitter performance requirements. These devices are well suited for the high density (4x10G) or 16x2.5G line card solutions required for next generation SONET/SDH networks.

    Superior Jitter Performance

    The standalone CDR and Transceiver (SERDES with CDR) products exceed the stringent SONET/SDH Jitter Generation specs for the transmitter (driving SFPs directly).

    The receivers have a lot of margin for Jitter Tolerance and also meet Jitter transfer specs for certain regenerator applications where it is required.

    Software Support

    Exar provides a full set of device driver software for all of its SONET/ SDH products via a concise set of API (Application Programming Interface) calls to configure, and manage the channels with or without interrupt handling. Exar's device driver software for SONET/SDH products are fully tested and are operating system and processor independent.

    Applications of SONET/SDH products

    Exar's world-class physical layer solutions are ideal for a wide variety of markets and applications:

    • Line cards
    • Access Concentrators
    • Multi-Service Provisioning Platforms (MSPP)



    Exar has a range of BITS clocks, SONET clocks, WAN clocks and VCO devices. These are used in system solutions for PDH, SONET/SDH and Carrier Ethernet network equipment.