Advance Data Sheet
March 2001
CA16-Type 2.5 Gbits/s DWDM Transponder with
16-Channel 155 Mbits/s Multiplexer/Demultiplexer
Transponder Interfacing
The TxD[0:15]P/N, TxR
EF
C
LK
P/N, and PIC
LK
P/N
inputs and the RxQ[0:15]P/N, POC
LK
P/N, and PC
LK
P/
N outputs are high-speed (155 Mbits/s), LVPECL differ-
ential data and clock signals.To maintain optimum sig-
nal fidelity, these inputs and outputs must be
connected to their terminating devices via 50 ¾ con-
trolled-impedance transmission lines. The transmitter
inputs (TxD[0:15]P/N, TxR
EF
C
LK
P/N, and PIC
LK
P/N)
must be terminated as close as possible to the CA16
transponder connector with a Thevenin equivalent
impedance equal to 50
Ω
terminated to Vcc – 2 V. The
receiver outputs (RxQ[0:15]P/N, POC
LK
P/N, and
PC
LK
P/N) must be terminated as close as possible to
the device (IC) that these signals interface to with a
Thevenin equivalent impedance equal to 50
Ω
termi-
nated to Vcc – 2 V.
Figure 3, below, shows one example of the proper ter-
minations. Other methods may be used, provided they
meet the requirements stated above.
Functional Description
(continued)
Loopback Modes
The
CA16-type transponder
is capable of operating in
either of two loopback modes: diagnostic loopback or
line loopback.
Line Loopback
When L
LOOP
is pulled low, the received serial data
stream and recovered 2488.32 MHz serial clock from
the optical receiver are connected directly to the serial
data and clock inputs of the optical transmitter. This
establishes a receive-to-transmit loopback at the serial
line rate.
Diagnostic Loopback
When D
LOOP
is pulled low, a loopback path is estab-
lished from the transmitter to the receiver. In this mode,
the serial data from the parallel-to-serial converter and
the transmit serial clock is looped back to the serial-to-
parallel converter and the frame and byte detect cir-
cuitry, respectively.
3.3 V
SONET/SDH
INTERFACE IC
130
Ω
50
Ω
IMPEDANCE
TRANSMISSION LINES
80
Ω
80
Ω
CONNECTOR
TxD[0:15]N
(LVPECL)
130
Ω
CA16-TYPE TRANSPONDER
TxD[0:15]P
(LVPECL)
MUX
Tx
TxLINE
3.3 V
130
Ω
130
Ω
50
Ω
IMPEDANCE
TRANSMISSION LINES
RxD[0:15]P
(LVPECL)
DEMUX
RxD[0:15]N
(LVPECL)
Rx
RxLINE
80
Ω
80
Ω
1-1054(F)
Figure 3. Transponder Interfacing
Agere Systems Inc.
13
AGERE [ AGERE SYSTEMS ]
