
Tunable SFP+ Optical Transceiver with Limiting Electrical Interface JST Series
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Section 1 Functional Description
The tunable SFP+ optical transceiver is a full duplex serial
electric, serial optical device with both transmit and receive
functions contained in a single module that provides a high-speed
serial link at 9.95 to 11.3 Gbps signaling rates. The transceiver
supports the Enhanced Small Form Factor Pluggable Module SFP+
specication SFF-8431 Rev. 4.1 for the electrical interface,
SFF-8690 Rev 1.4 for the tunability interface, SFF-8432 Rev. 5.0
for the mechanical interface, and SFF-8472 Rev. 11.3 for the
management interface. Figure 1 shows a block diagram.
VCCT
VCCT
VEET
VEET
VEERVCCR
RD–
TD–
TD+
RX_LOS
MOD_ABS
RS1
RS0
TX_FAULT
TX_DIS
RD+
SCL
SDA
Power Supply Sequence/
In-Rush Control Circuit
Transceiver Ground
ROSA
TIA
TOSA
Mod.
Driver
Tunable
ASIC
Figure 1. Lumentum tunable SFP+ optical transceiver functional
block diagram
The transceiver has several low-speed interface connections.
These connections include: transmitter fault (Tx_Fault),
transmitter disable (Tx_Disable), module absent (Mod_ABS),
receive loss of signal (Rx_LOS), and a 2-wire serial interface clock
(SCL) and data (SDA). Rate select (RS0 and RS1) is not used in this
product.
The transceiver supports the SFI electrical interface. The
electrical interface is based on a high-speed, low-voltage logic
AC-coupled linear interface with a 100 Ω nominal differential
impedance.
Transmitter
The transmitter path converts serial NRZ electrical data from
9.95 to 11.3 Gbps line rates to a standard compliant optical
signal.
Inside the module, the differential signal is coupled into the
modulator driver which transforms the small swing voltage to an
output modulation that drives a cooled InP Integrated Laser
Mach-Zehnder (ILMZ) modulator. The optical signal is engineered
to meet the 10 Gigabit Ethernet, 10 G FC, and corresponding
FEC-rates and DWDM specications at ITU grids with 50 GHz
channel spacing. Closed-loop control of the transmitted laser
power and modulation swing over temperature and voltage
variations are provided. The laser is coupled to a single-mode
optical ber through an industry-standard LC optical connector.
Receiver
The receiver converts incoming DC-balanced serial NRZ 9.95 to
11.3 Gbps line rate optical data into serial SFI electrical data.
Light is coupled to an APD from single-mode optical ber through
an industry-standard LC optical connector. The electrical current
from the APD is converted to voltage in a limiting
transimpedance amplier.
The amplied signal is output directly on the RD+ and RD− pins
as a 100 Ω CML signal.
Low-Speed Signaling
Low-speed signaling is based on low-voltage TTL (LVTTL)
operating at a nominal voltage of 3.3 V. Hosts should use a
pull-up resistor connected to VCC 3.3 V on the 2-wire interface
SCL, SDA, and all low-speed outputs.
Low-Speed Interface
Connections Denition
SCL/SDA 2-wire serial interface clock and data line.
Tx_Fault Output pin. When asserted high, indicates that the
module has detected a transmitter fault condition
related to laser operation or safety.
Tx_Disable Input pin. When asserted high or left open, the
transmitter output is turned off. When Tx_Disable
is asserted low or grounded, the module
transmitter is operating normally.
RS0 and RS1 Input pins. These pins are not used in this product.
Mod_ABS Output pin. Asserted high when the SFP+ module
is absent and is pulled low when the SFP+ module
is inserted.
Rx_LOS Output pin. Asserted high when insufcient
optical power for reliable signal reception is
received.