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#1 2017-Apr-01 03:38:38

Registered: 2016-Jul-04
Posts: 8

Reference signal for CM-PLL


We are now trying to build a distributed MIMO system. In order to synchronize RF and sampling clock, we want to use CM-PLL and a external clock as input. For the CM-PLL, according to https://warpproject.org/trac/wiki/Hardw … figuration and https://warpproject.org/trac/wiki/cores … controller, it can use a 10MHz signal from MMCX Jack as reference singal. Am I right?

For the reference signal, what will be the requirement? For example can it be a square wave or needs to be a sine wave. what about the voltage?




#2 2017-Apr-03 10:11:37

From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: Reference signal for CM-PLL

The MMCX jack drives the CLKIN0 port of the LMK00304 clock buffer, which supports a wide range of input voltages and slew rates. A reference clock with faster slew rate (i.e. sharper high/low transitions) will reduce jitter, though for most applications I would guess either a sinusoid or square wave would work fine. The LMK00304 supports input voltages up to its supply (3.3v); I would suggest ~1V swing to avoid any issues with hitting the rails.



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