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The synchronization and output swing problems of HMC7043

Question asked by fylhss on Mar 8, 2017
Latest reply on Mar 13, 2017 by kpeker

Hi,

    Now,i am using HMC7043.The CLKIN is 2.4GHz, i want to get seven  2.4Ghz  and seven 18.75MHz.I have some questions about  HMC7043.

1) the  problems about sysrefout synchronization.

Betweent seven sysrefout clocks, there ocassionly occured one CLKIN phase difference.
and the readback value from the register 0x091 is 0x0a,which is mean the FSM is runing,but value from the register 0x07d is 0x00,which means phase of output is not stable.Does it mean HMC743 has never  been synchronized?

some registers are confiured below:

0x0003  - 0x24;

0x000a  - 0x06;

0x005c - 0x00;

0x005d - 0x04;

0x005a -0x07;

0x005b - 0x05;

 

0x00c8 - 0xF1;

0x00c9 - 0x01;

0x00ca - 0x00;

0x00d0 - 0x08;

 

0x00d2 - 0xFD;

0x00D3 - 0X80;

0x00D4 - 0X00;

0x00DA - 0X08;

...

 

0x0001 - 0x42;

0x0001 - 0x40;

0x0002 - 0x00;

0x0002 - 0x02;

0x0001 - 0xc0;

0x0001 -0x44;

Is thers someting wrong?

 

2) The swing of 2.4GHz sclkout is just 800mVpp ,can not reach about 1050mVpp which is labeled in the Figure.6 .Output mode is LVPECL AC coupled. before the  AC coupled capicator,i placed 240ohm resistor  betweem sclkoutp/n and GND.

Although i have write 0xDF to  the register 0x00a0,there is no effect.Why?

Is there some else setting? 

 

 

By the way ,i have the fellowing questions :
1. Should REFSYINP/N be ac coupled? Does it only need one pulse?
2. if i have one hmc7043 in my system , can it sync all output clocks thought SPI?
if i use REFSYINP/N to sycn all output , if  the domin of REFSYINP/N is not critial?

 

Thanks very much!

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