1.0625Gbps to 10.32Gbps, Integrated, Low-Power SFP+ Limiting Amplifier and VCSEL Driver

Industry's First Combination VCSEL Driver and Limiting Amp for 10G SFP+ Ethernet and Fibre Channel

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The MAX3798 is a highly integrated limiting amplifier and VCSEL driver designed for 1x/2x/4x/8x Fibre Channel transmission systems at data rates up to 8.5Gbps as well as for 10GBASE-SR transmission systems at a data rate of 10.3125Gbps. Operating from a single +3.3V supply, this low-power integrated limiting amplifier and VCSEL driver IC enables a platform design for SFP MSA as well as for SFP+ MSA-based optical transceivers. The high-sensitivity limiting amplifier limits the differential input signal generated by a transimpedance amplifier into a CML-level differential output signal. The compact VCSEL driver provides a modulation and a bias current for a VCSEL diode. The optical average power is controlled by an average power control (APC) loop implemented by a controller that interfaces to the VCSEL driver through a 3-wire digital interface. All differential I/Os are optimally back-terminated for a 50Ω transmission line PCB design.

The use of a 3-wire digital interface reduces the pin count while enabling advanced Rx (mode selection, LOS threshold, LOS squelch, LOS polarity, CML output level, signal path polarity, slew-rate control, deemphasis, and fast mode-select change time) and Tx settings (modulation current, bias current, polarity, programmable deemphasis, eye-crossing adjustment, and eye safety control) without the need for external components. The MAX3798 provides multiple current and voltage DACs to allow the use of low-cost controller ICs.

The MAX3798 is packaged in a lead-free, 5mm x 5mm, 32-pin TQFN package.
MAX3798: Typical Application Circuit MAX3798: Typical Application Circuit Enlarge+

Key Features

  • Low Power Dissipation of 320mW at 3.3V Power Supply
  • Up to 10.32Gbps (NRZ) Operation
  • 3mVP-P Receiver Sensitivity at 10.32Gbps
  • 4psP-P DJ at Receiver Output at 8.5Gbps 8B/10B
  • 4psP-P DJ at Receiver Output at 10.32Gbps 231 - 1 PRBS
  • 26ps Rise and Fall Time at Rx/Tx Output
  • Mode Select for High-Gain Mode and High-Bandwidth Mode
  • CML Output Slew-Rate Adjustment for High-Gain Mode
  • CML Output with Continuous Level Adjustment
  • CML Output Squelch
  • Polarity Select for Rx and Tx
  • LOS Assert Level Adjustment
  • LOS Polarity Select
  • Modulation Current Up to 12mA Into 100Ω Differential Load
  • Bias Current Up to 15mA
  • Integrated Eye Safety Features
  • Selectable Deemphasis at Rx Output
  • 3-Wire Digital Interface
  • Eye-Crossing Adjustment of Modulation Output
  • Programmable Deemphasis at Tx Output
  • Fast Mode-Select Change Time of 10µs


  • 10GBASE-LR SFP+ Optical Transceiver (1310nm VCSEL)
  • 10GBASE-LRM SFP+ Optical Transceiver (1310nm VCSEL)
  • 10GBASE-SR SFP+ Optical Transceiver
  • 1x/2x/4x/8x SFF/SFP/SFP+ MSA Fibre Channel (FC) Optical Transceiver

See parametric specs for Laser Drivers (19)

Part NumberTarget Oper. Range
Data Rate
Data Rate
(min)(max)(typ)(max)(max)(See Notes)
1 to 4.5
5 to >10
$3.52 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX3798EVKIT: Evaluation Kit for the MAX3798
Product Reliability Reports: MAX3798.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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