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AR# 22182

Spartan-3/-3E /-3A /-3AN /-3A DSP、DCM - CLKFX と CLKFX180 の間の位相エラーについて

説明

データシートには CLKOUT_PHASE パラメータがあり、CLK0 と DFS 出力間の位相オフセットを定義しています。 CLKFX と CLKFX180 間の位相オフセットについて教えてください。

ソリューション

CLKFX_180 is not a phase-shifted version of CLKFX; it is simply CLKFX inverted. Therefore, the phase error between CLKFX and CLKFX180 will be minimal. The delay associated with the inverter can be safely ignored.

The phase offset of CLKFX180, in respect to CLK0, will depend on the phase offset of CLKFX (defined by CLKOUT_PHASE in the data sheet) and the duty-cycle of CLKFX (defined by CLKOUT_DUTY_CYCLE_FX in the data sheet). The duty-cycle will be very close to 50/50 at the DFS output.

If CLKFX and CLKFX180 are used as a complimentary clock solution, such as with DDR, their 180 degree shift should be maintained.

The Spartan-3 DC and Switch Characteristic Data Sheet is located at:

http://www.xilinx.com/xlnx/xweb/xil_publications_display.jsp?sGlobalNavPick=&sSecondaryNavPick=&category=-1209734&iLanguageID=1

AR# 22182
日付 12/15/2012
ステータス アクティブ
種類 一般
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