2–10 Altera Corporation
Stratix GX Transceiver User Guide January 2005
Receiver Analog
Figure 2–8. Receiver Input Buffer
Programmable Receiver Termination
The Stratix GX receiver buffer includes programmable on-chip
differential termination of 100, 120, or 150 Ω..
This assignment must be made per pin through the Assignment Editor in
the Quartus II software. Select Assignment Organizer > Options for
Individual Nodes Only > Stratix GX Termination Value (Assignments
menu).
1 The proper termination settings should be selected and verified
accordingly before compilation.
The transmitter PLL input signal (inclk) drives the termination
resistance calibration circuit. The Quartus II software allows
receiver-only configurations in Stratix GX devices. However, if you use
the Quartus II software to remove the transmitter PLL in a receiver-only
configuration, you will see an incorrect value or unpredictable behavior
with the receiver input pin termination. If the rx_cruclk signal is
globally routed, the Quartus II software handles this automatically. If the
rx_cruclk signal is not globally routed or routed using the inter-
quadrant line (IQ2), the Quartus II software returns a no-fit. In this
situation, you must add a transmitter PLL to your design.
If the pll_areset (analog reset) signal goes high, the RX_Vcm value is
less than the 1.1 V. This value varies unpredictably because the circuit is
tristated. RX_Vcm is referenced from the Stratix GX receiver analog power
supply.
Input Buffer
Input Pins
Internal Loopback
from Transmitter
Programmable
Equalizer
Programmable
Termination
To PLD
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