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HMC830 - SPI Programming - Minimum starting sequence?

Question asked by MarkusNTHFS on Jul 7, 2015
Latest reply on Jul 8, 2015 by MarkusNTHFS

Hello!

 

I'm trying to configure the HMC830 with an 80MHz reference frequency (3.3V) to an output frequency of 2GHz.

Therefore I calculated the divider values to be R=1, N=25, Nfrac=0, output divider=1.

 

So I programmed the register 0x05 twice (for AutoCal on the VCO), then the registers 0x02, 0x03 and 0x04 with values: (Shown: Bits on SPI data line)
0x05: 0xA01C120

0x05: 0xA000000

0x02: 0x4000002

0x03: 0x6000032

0x04: 0x8000000

But then I get an output frequency of 2.546GHz.

The soldered Loop Filter is the one from the datasheet with B=74kHz bandwidth.

 

So I search the datasheet and the operating guide for more information about some "minimal needed programming" for the device to work, but did not find any.

Do you known of any such thing? Or maybe you see the mistake I made/make with this sequence?

 

BR,

Markus

 

PS: I verified the programming by just reprogramming

0x05: 0xA000000

after the sequence. Then the output is at 2.974GHz, so at the upper end as expected. So I assume that the chip is ok so far.

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