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10–28
Altera Corporation
Stratix Device Handbook, Volume 2
July 2005
I/O Structure
The differential I/O within Stratix GX also provides dynamic phase
alignment (DPA). DPA enables the differential I/O to operate up to
1 Gbps per channel. DPA automatically and continuously tracks
fluctuations caused by system variations and self-adjusts to eliminate the
phase skew between the multiplied clock and the serial data. The block
contains a dynamic phase selector for phase detection and selection, a
SERDES, a synchronizer, and a data realigner circuit. You can bypass the
dynamic phase aligner without affecting the basic source-synchronous
operation of the channel by using a separate deserializer.
If you compile an APEX II LVDS design that uses clock-data
synchronization (CDS) for a Stratix or Stratix GX device, the Quartus II
software issues a warning during compilation that Stratix and Stratix GX
devices do not support CDS.
Stratix and Stratix GX devices offer a flexible solution using new byte
realignment circuitry to correct for byte misalignment by shifting, or
slipping, data bits. Stratix and Stratix GX devices activate the byte
realignment circuitry when an external pin (rx_data_align) or an
internal custom-made state machine asserts the SYNC node high.
APEX II, APEX 20KE, and APEX 20KCdevices have a dedicated
transmitter clock output pin (LVDSTXOUTCLK). In Stratix and Stratix GX
devices, a transmitter dataout channel with an LVDS clock (fast clock)
generates the transmitter clock output. Therefore, you can drive any
Table 10–10. Number of Dedicated DIfferential Channels in Stratix GX
Device
Pin Count
Number of
Transceivers
Number of Source-
Synchronous
Channels
EP1SGX10 C
672
4
22
EP1SGX10 D
672
8
22
EP1SGX25 C
672
4
39
EP1SGX25 D
672/1,020
8
39
EP1SGX25 F
1,020
16
39
EP1SGX40 D
1,020
8
45
EP1SGX40 G
1,020
20
45
(1)
For information on channel speeds, see the Stratix GX Device Family Data Sheet
section of the Stratix GX Device Handbook, Volume 1 and the High-Speed
Source-Synchronous Differential I/O Interfaces in Stratix GX Devices chapter of the
Stratix GX Device Handbook, Volume 2.