Altera Corporation
5–13
January 2008
Stratix II Device Handbook, Volume 2
High-Speed Differential I/O Interfaces with DPA in Stratix II and Stratix II GX Devices
Fast PLL
The high-speed differential I/O receiver and transmitter channels use the
fast PLL to generate the parallel global clocks (rx- or tx- clock) and
high-speed clocks (diffioclk).
Figure 5–12 shows the locations of the
fast PLLs. The fast PLL VCO operates at the clock frequency of the data
rate. Each fast PLL offers a single serial data rate support, but up to two
separate serialization and/or deserialization factors (from the C0 and C1
fast PLL clock outputs) can be used. Clock switchover and dynamic fast
PLL reconfiguration is available in high-speed differential I/O support
mode.
f
Stratix II GX Handbook.
Figure 5–12 shows a block diagram of the fast PLL in high-speed
differential I/O support mode.
Figure 5–12. Fast PLL Block Diagram
(1)
Stratix II fast PLLs only support manual clock switchover.
(2)
The global or regional clock input can be driven by an output from another PLL, a pin-driven dedicated global or
regional clock, or through a clock control block provided the clock control block is fed by an output from another
PLL or pin-driven dedicated global or regional clock.
(3)
In high-speed differential I/O support mode, this high-speed PLL clock feeds the SERDES. Stratix II devices only
support one rate of data transfer per fast PLL in high-speed differential I/O support mode.
(4)
This signal is a high-speed differential I/O support SERDES control signal.
(5)
If the design enables this ÷2 counter, the device can use a VCO frequency range of 150 to 520 MHz.
Charge
Pump
VCO
÷c1
8
4
8
Clock
Input
PFD
÷c0
÷m
Loop
Filter
Phase
Frequency
Detector
VCO Phase Selection
Selectable at each PLL
Output Port
Post-Scale
Counters
Global clocks
diffioclk0 (3)
loaden0 (4)
diffioclk1 (3)
loaden1 (4)
Regional clocks
to DPA block
Global or
regional clock (2)
Global or
regional clock (2)
÷c2
÷c3
÷n
4
Clock (1)
Switchover
Circuitry
Shaded Portions of the
PLL are Reconfigurable
÷k
(5)