Altera Corporation
2–11
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
Figure 2–3
shows an example termination scheme for a reference clock
signal when configured as HCSL.
Figure 2–3. DC Coupling and External Termination Scheme for PCI Express
Reference Clock
Notes (1)
,
(2)
Notes to
Figure 2–3
:
(1)
No biasing is required if the reference clock signals are generated from a clock
source that conforms to the PCI Express specification.
(2)
Select resistor values as recommended by the PCI Express clock source vendor.
Transmitter PLL Block
The transmitter PLL block contains two transmitter PLLs (transmitter
PLL0 and transmitter PLL1) per transceiver block, as shown in
Figure 2–4
. The transmitter PLL block multiplies the reference clock to the
frequency required to support the serial data rate. Transmitter PLL0 and
transmitter PLL1 can support data rates from 600 Mbps to 6.375 Gbps.
Each PLL has a dedicated locked signal (
pll_locked
) that is fed to the
PLD logic array to indicate when the PLLs are locked to the reference
clock.
PIPE
1.2-V PCML, 1.5-V PCML,
3.3-V PCML, Differential
LVPECL, LVDS
AC
On-chip
HCSL
(1)
DC
External
(2)
Notes to
Table 2–3
:
(1)
In PIPE mode, you have the option of selecting the HCSL standard for the
reference clock if compliance to PCI Express is required. The Quartus II software
automatically selects DC coupling with external termination for the
REFCLK
signal if configured as HCSL.
(2)
Refer to
Figure 2–3
for an example termination scheme.
Table 2–3. Reference Clock Specifications (Part 2 of 2)
Protocol
I/O Standard
Coupling
Termination
PCI Express
(HCSL)
REFCLK
Source
REFCLK
+
REFCLK
-
Stratix II GX
Rs
Rs
Rp
=
50
Ω
Rp
=
50
Ω
(2)
(2)
Содержание Stratix II GX
Страница 640: ...4 244 Altera Corporation Stratix II GX Device Handbook Volume 2 October 2007 Document Revision History ...
Страница 642: ...4 246 Altera Corporation Stratix II GX Device Handbook Volume 2 October 2007 Document Revision History ...
Страница 672: ...6 14 Altera Corporation Stratix II GX Device Handbook Volume 2 October 2007 Document Revision History ...