
2–16
Altera Corporation
Stratix II GX Device Handbook, Volume 1
October 2007
Transceivers
Figure 2–13. Programmable Receiver Termination
If a design uses external termination, the receiver must be externally
terminated and biased to 0.85 V or 1.2 V.
Figure 2–14 shows an example
of an external termination and biasing circuit.
Figure 2–14. External Termination and Biasing Circuit
Programmable Equalizer
The Stratix II GX receivers provide a programmable receive equalization
feature to compensate the effects of channel attenuation for high-speed
signaling. PCB traces carrying these high-speed signals have low-pass
filter characteristics. The impedance mismatch boundaries can also cause
signal degradation. The equalization in the receiver diminishes the lossy
attenuation effects of the PCB at high frequencies.
Differential
Input
Buffer
50, 60, or 75
Ω
50, 60, or 75
Ω
VCM
Transmission
Line
C1
R1/R2 = 1K
VDD × {R2/(R1 + R 2)} = 0.85/1.2 V
50/60/75-
Ω
Termination
Resistance
R1
R2
VDD
Receiver External Termination
and Biasing
Stratix II GX Device
Receiver External Termination
and Biasing
RXIP
RXIN
Receiver