Chapter 2: Arria GX Architecture
2–11
Transceivers
The receiver has 100- on-chip differential termination (RD OCT) for different
protocols, as shown in Figure 2–11. You can disable the receiver’s internal termination
if external terminations and biasing are provided. The receiver and transmitter
differential termination method can be set independently of each other.
Figure 2–11. Receiver Input Buffer
100-Ω
Termination
Input
Pins
Programmable
Equalizer
Differential
Input
Buffer
If a design uses external termination, the receiver must be externally terminated and
biased to 0.85 V or 1.2 V. Figure 2–12 shows an example of an external termination and
biasing circuit.
Figure 2–12. External Termination and Biasing Circuit
Receiver External Termination
and Biasing
Arria GX Device
V
DD
50-W
Termination
Resistance
R1
C1
Receiver
R1/R2 = 1K
´ {R2/(R1 + R 2)} = 0.85/1.2 V
RXIP
V
R2
DD
RXIN
Receiver External Termination
and Biasing
Transmission
Line
Programmable Equalizer
The Arria GX receivers provide a programmable receiver equalization feature to
compensate for the effects of channel attenuation for high-speed signaling. PCB traces
carrying these high-speed signals have low-pass filter characteristics. Impedance
mismatch boundaries can also cause signal degradation. Equalization in the receiver
diminishes the lossy attenuation effects of the PCB at high frequencies.
© December 2009 Altera Corporation
Arria GX Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
