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how to calculate register to have a good frequency on HMC769 ?

hi,

I am programming the HMC769 by spi without your application and I have a probleme. I don't understand the VCO_TO_SYNTH_DIV 2 or VCO_TO_SYNTH_DIV 4 ? when do i change this ?

What is it the good formula to calculate the différente register ? please ?

My configuration is this and I want to have the law to change the frequency every 0.2MHz for example between 9.42 to 9.52Ghz (512 possibility):

REVISION 3.2.8.0
REG 0 97370
REG 1 2
REG 2 1
REG 3 2B
REG 4 6D097B
REG 5 DEADBE
REG 6 3FDE
REG 7 104845
REG 8 36FFF
REG 9 3F7FFF
REG A 1
REG B 1E071
REG C 1F
REG D 0
REG E 0
REG F 1
REG 11 0
REG 12 3
REG 13 1259
REG 14 0
REG 15 0
REG 16 0
REG 17 0
REG 18 0
REG 19 0
REG 1A 0
REG 1B 0
REG 1C 0
REG 1D 0
REG 1E 0
REG 1F 0
REG 10 0
XTAL 54
DIVIDER_MANUAL_MODE 1
VCO_TO_SYNTH_DIV 4
VCO_TO_OUT_DIV 1

Thank you.

Best regard.

  • Hi,

    VCO_TO_SYNTH_DIV is the parameter used for calculations in GUI.

    The fVCO/2 is driven to synthesizer as seen in the block diagram. N counter supports 4GHz max so the /2 prescaler must be enabled (set 0x08[17] =1). Hence the fVCO/4 is fed to the N divider. All the calculations should be done by using this divided frequency.

    Shortly, to generate 9.42GHz to 9.52GHz range by 200kHz steps, you should make calculations for 2.355GHz to 2.38GHz range by 50kHz steps.

    Regards,

    Kazim