MAX3945：1.0625Gbps to 11.3Gbps, SFP+ Dual-Path Limiting Amplifier

1Gbps to 11Gbps Limiting Amp Enables < 1W SFP+ Optical Transceiver Modules

The MAX3945 is a +3.3V, multirate, low-power limiting amplifier optimized for Fibre Channel and Ethernet transmission systems at data rates up to 11.3Gbps. The high-sensitivity limiting amplifier limits the signal generated by a transimpedance amplifier into a CML-level differential output signal. All differential inputs and outputs (I/O) are optimally back terminated for 50Ω transmission line PCB design. The MAX3945's dual-path limiting amplifier has programmable filtering to optimize sensitivity for different data rates and to suppress relaxation oscillations that could occur in some optical systems. The MAX3945 incorporates two loss-of-signal (LOS) circuits and a programmable time mask for the LOS output. A 3-wire digital interface reduces the pin count and enables control of LOS threshold, LOS polarity, LOS mode, CML output level, input offset correction, receive (Rx) polarity, Rx input filter, and Rx deemphasis without the need for external components. The MAX3945 is packaged in a 3mm x 3mm, 16-pin TQFN package.

Key Features

130mW Power Dissipation Enables < 1W SFP+ Modules
Enables Single-Module Design Compliance with 1000BASE-SX/LX and 10GBASE-SR/LR Specifications
-25.3dBm Optical Sensitivity at 1.25Gbps Using a 10.32Gbps ROSA
Selectable 1GHz/2.1GHz/2.5GHz/3GHz Input Filters at RATE_SEL = 0 Setting
Supports SFF-8431 SFP+ MSA and SFF-8472 Digital Diagnostic
Total Power Dissipation of 130mW at 3.3V Power Supply with RSSI Monitor-Based LOS
Total Power Dissipation of 154mW at 3.3V Power Supply with Rx Input-Based LOS
4mVP-P Input Sensitivity at 11.3Gbps
4psP-P DJ at 11.3Gbps with RATE_SEL = 1
4psP-P DJ at 8.5Gbps with RATE_SEL = 1
5psP-P DJ at 4.25Gbps with RATE_SEL = 0, BW1 = 1, BW0 = 1
9.0psP-P DJ at 1.25Gbps with RATE_SEL = 0, BW1 = 0, BW0 = 0
26ps Rise and Fall Time with RATE_SEL = 1
52ps Rise and Fall Time with RATE_SEL = 0
CML Output with Level Adjustment and Squelch Mode
Programmable CML Output Deemphasis
CML Output Polarity Select
LOS Polarity Select
Programmable Masking Time for the LOS Output
LOS Assert/Deassert Level Adjustment
Choice of Rx Input-Based LOS or RSSI Monitor-Based LOS
3-Wire Digital Interface Compatible with Maxim’s SFP+ Family of Products

MAX3945: Typical Application Circuit

Applications/Uses

10G PON ONU
10GBASE-SR/LR SFP+ Optical Transceiver
1x/2x/4x/8x SFF/SFP/SFP+ MSA Fibre-Channel Optical Transceiver

DataSheet

title	Download file
MAX3945 Data Sheet	MAX3945.pdf

Parametrics

Part Number	Target Oper. Range (Gbps)	Data Rate (Mbps)	Data Rate (Mbps)	V_SUPPLY (V)	I_CC (mA)	I/O Type	Input Sens. (mV)	LOS Sens. (mV)	Edge Speed (ps)	Package/Pins	Budgetary Price
Part Number	Target Oper. Range (Gbps)	min	max	V_SUPPLY (V)	typ	I/O Type	Input Sens. (mV)	min	max	Package/Pins	See Notes
MAX3945	5 to >10	1062	11300	3.3	39	CML	4	5.1	35	TQFN/16	$4.00 @1k