problem with Low output voltage level in hmc7043

Hi.

I'm using hmc7043 in my design, so that I drive it with lmx2581 at 2GHz with -1.5dbm output voltage level.i enable only clkout0, then disable sync and slip in it. i set  divider ratio to 1 in asynchronous mode. the output driver mode is lvpecl. when i look at output signal level, i found it to be very low. and it is -15dbm, then i opened the load from it. at this manner the output level is -5dbm. then i set divider ratio to 4  ,8 ,16 and 32 respectively and I see that the output level will be increased when output frequency decreased. At now I'm confused with it, please help me what do i do for obtain optimum swing level

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  • 0
    •  Analog Employees 
    on Jan 23, 2020 12:26 PM

    Hi, 

    HMC7043 does not have internal dc resistor for LVPECL operation. You need to provide DC path from pin to ground with a resistor (typically around ~150 ohm). Do you have it, if so what is the value of this resistor? 

    Also, Table 40 in datasheet have reserved register update for performance update (Reg0x9F and Reg0xA0). Did you update these registers?

    Regards,

    Kudret

Reply
  • 0
    •  Analog Employees 
    on Jan 23, 2020 12:26 PM

    Hi, 

    HMC7043 does not have internal dc resistor for LVPECL operation. You need to provide DC path from pin to ground with a resistor (typically around ~150 ohm). Do you have it, if so what is the value of this resistor? 

    Also, Table 40 in datasheet have reserved register update for performance update (Reg0x9F and Reg0xA0). Did you update these registers?

    Regards,

    Kudret

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