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ADF4158 SPI Interface

Question asked by junlovecc on Jun 17, 2016
Latest reply on Jun 24, 2016 by rbrennan

Hello Everyone,

My team at my university is using the ADF4158 PLL alongside HMC509 as synthesizer to eliminate the non-linearity of the 509 VCO. We are feeding back the RFOut/2 output port (which shall be ~ 4GHz within the lock range of ADF4158). We are very new to interfacing with this chip (or any chips at all). We are using Teensy 3.1 SPI to configure the PLL. However, the PLL is constantly outputting 5V and consequently the VCO is always fixed at around 7.2GHz.

 

I have attached our team's design as a PDF alongside this message (including the arduino code (for the Teensy) that we used to program the PLL and SPI MOSI waveform with SCK and LE).  The waveform is too big to show, so I have recorded a video on my logic analyzer output (Saleae Logic) to show it.

 

The PLL uses 10MHz as reference as do the Evaluation board.

 

So far, I am only able to get 5V output  out of the charge pump and changing R0's integer counter value does not modify our output frequency; setting MSB of R0 to 1 doesn't put the PLL into sweep mode either! I have confirmed that the arduino's SPI output via logic analyzer and confirmed that it matches that of the ADF4158 (SPI MODE 1). I have also attempted to check the register values with MUXOUT pin but I couldnt get any output at all... Is there anything with our code (for both writing/reading) and/or our hardware design? Please let us know! Thank you!!!

 

Thank you so much for your help!!!!

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