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HMC960: Weird waveforms on output

Question asked by skobec on Jul 21, 2017
Latest reply on Jul 21, 2017 by skobec

Greetings!

 

@jdobler

I'm using HMC960 in combination with TIA AD8015 to amplify small signals that my pin diode is receiving. 

When there is no HMC960 on my PCB, AD8015 is working perfectly and it is outputting correct waveforms. But as soon I include HMC960 into circuit  there are weird signals going into HMC960 and out of it.

 

I took photos of the outputs of HMC960. I'm amplifying signal of frequency of 500 kHz.

On first photo you can see the general waveform that is messing up with my signal. If i zoom in into different parts I can find my signal.

 

In last photo you can find my schematic. CMQ is on 1.8 volts, decoupled with 100 nF capacitor.

Outputs are open.

I'm using SPI pins for configuring registers. Data that I'm sending is as followed:

 

Register 1:
0000 0000 0000 0000 0000 0010 0000 1110  
Register 2:
0000 0000 0000 0000 1011 1001 0001 0110

Register 3:
0000 0000 0000 0000 0000 0000 0001 1110

 

I tried playing with different settings, so far everything produces same result.

 

Thank you for your help.

 

With best regards,

Marko

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