Altera Corporation
9–13
July 2005
Stratix Device Handbook, Volume 2
Implementing SFI-4 in Stratix & Stratix GX Devices
Software Implementation
The SFI-4 interface uses a 16-bit LVDS I/O interface. The Altera
Quartus II software version 2.0 supports Stratix and Stratix GX devices,
allowing you to implement LVDS I/O buffers through the Quartus II
Assignment Organizer.
f
For information on the Quartus II Assignment Organizer, see the
Quartus II Software Help.
Conclusion
SFI-4 is the standard interface between SONET framers and optical
SERDES for OC-192 interfaces. With embedded SERDES and fast PLLs,
Stratix and Stratix GX devices can easily support the SFI-4 framer
interface, enabling
10-Gbps (OC-192) data transfer rates. Stratix and Stratix GX I/O supports
the required data rates of up to 622.08 Mbps. Stratix and Stratix GX fast
PLLs are designed to support the high clock frequencies and one-to-one
relationship needed for interfaces such as XSBI and SFI-4. Stratix and
Stratix GX devices can support multiple SFI-4 functions on one device.
Table 9–7. Framer LVDS DC Specifications
Parameter
Value
Unit
Min
Typ
Max
Output differential voltage (VOD)
250
mV
Output offset voltage (VOS)
1,125
1,375
mV
Output Impedance, single ended
40
140
W
Change in VOD between ‘0’ and '1'
50
mV
Change in VOD between '1' and '0'
50
mV
Input voltage range (VI)
0
2,400
mV
Differential impedance
100
W
Input differential voltage (VID)
100
600
mV
Receiver differential input impedance
70
130
W
Ground potential difference (between PCS and PMA)
50
mV
Rise and fall times (20% to 80%)
100
400
ps
(1)
The IEEE standard requires 400 mV. A larger swing is encouraged, but not required.