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Newbie
Newbie
298 次查看
注册日期: ‎05-13-2020

IDELAYE3/ODELAYE3模块使用

在UltraScale系列数据手册中,IDELAY/ODELAY的tap分辨率为2.5~15ps。在UltraScale+系列数据手册中,IDELAY/ODELAY的tap分辨率为2.1~12ps.但是在实际应用中,无法达到2.1或者2.5ps分辨率,请问应该如何去调整模块的tap分辨率呢?

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Moderator
Moderator
280 次查看
注册日期: ‎11-05-2010

回复: IDELAYE3/ODELAYE3模块使用

IDELAY/ODELAY的Tap 的分辨率由IDELAYCTRL 的Reference clock frequency 决定.

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Newbie
Newbie
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注册日期: ‎05-13-2020

回复: IDELAYE3/ODELAYE3模块使用

您好,在COUNT模式,无需例化IDELAYCTRL模块,应该怎么确定TAP分辨率呢

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Guide
Guide
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注册日期: ‎01-24-2009

回复: IDELAYE3/ODELAYE3模块使用

The resolution of the Tap of I DELAY / ODELAY is determined by the Reference clock frequency of IDELAYCTRL

While this is true of a 7 series device, it is not true of UltraScale/UltraScale+.

In the 7 series devices, there are 32 taps in the delay chain, and each is calibrated to a known delay using the IDELAYCTRL's reference clock - with each tap being Tref_clk/64.

In the UltraScale/UltraScale+, the taps themselves are not calibrated - this is why the datasheet gives the delays as being between 2.5ps and 15ps - this is the variation over Process, Voltage and Temperature (PVT). There is nothing you can do to change this - this is the physical characteristic of the tap.

In UltraScale/UltraScale+, rather than try and calibrate the tap, you have two modes:

  • COUNT: In this mode you control the number of taps, but the delay varies over PVT in the range of 2.5ps to 15ps per tap (UltraScale) - no IDELAYCTRL is used/needed
    • You don't know what the actual delay is
    • This is useful for any system that is doing dynamic calibration - where a customer designed state machine is dynamically adding/subtracting taps to the interface in order to find the best place to sample
  • TIME: The IDELAYCTRL is used to determine how many taps are required in order to obtain a given amount of time. The IDELAYCTRL does this dynamically - as PVT changes, the IDELAYCTRL changes the number of taps used in order to keep the time of the IDELAY/ODELAY as close to the requested TIME provided (as determined by the period of the REFCLK provided to the IDELAYCTRL)

Avrum

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Newbie
Newbie
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注册日期: ‎05-13-2020

回复: IDELAYE3/ODELAYE3模块使用

谢谢,如果说IDELAYE3模块无法精确达到2.1ps的分辨率,请问有什么其他的模块或者方法可以达到0.1ps或者是1ps的延时分辨率呢?

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