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.