Why 4*LO has problems in AD8333

Really thank you for your help.

I am struggling with the application of AD8333.

I am confused that when I input 4*LO sine wave to Din of DS90C401, its output (Dout-, Dout+) was not a sine wave. Even though I adjust the amplitude of the input. It still could not work.

I don't how to solve this issue. 

The purple trace with a sine wave is the input to Din of DS90C401,but the other two traces were Dout(+, -). I don't know why they were not sinewave.

Thanks for your kind help

Parents
  • 0
    •  Analog Employees 
    on Dec 12, 2019 12:55 AM over 1 year ago

    Hi,

    Can you provide a schematic of your circuit? Do you have the transimpedance amplifiers on the outputs of the AD8333? See Figure 64 in the AD8333 datasheet as a reference.

  • In addition, I also made an AD8333 circuit board without the previous VGA differential conversion module because I did that on another board in advance. According to the official recommendation, I used LVDS DS90C401 before my input reference signal entered 4LO. I looked up a lot of articles that told me the LVDS was used to process a digital signal instead of an analog signal. So I was confused that if 4LO's input should be an analog or digital signal. If it is a digital signal like a square wave, how they perform the mixing operation?  The following figure shows the schematic.

    When I changed a sine wave as the reference and I canceled the connection of DS90C401. The output was still wrong. I/Q could not track the tested signal's amplitude or phase. 

    I am really upset about its application because I have spent plenty of time to study it. But the outcome was always filled with errors.

    Best wishes

Reply
  • In addition, I also made an AD8333 circuit board without the previous VGA differential conversion module because I did that on another board in advance. According to the official recommendation, I used LVDS DS90C401 before my input reference signal entered 4LO. I looked up a lot of articles that told me the LVDS was used to process a digital signal instead of an analog signal. So I was confused that if 4LO's input should be an analog or digital signal. If it is a digital signal like a square wave, how they perform the mixing operation?  The following figure shows the schematic.

    When I changed a sine wave as the reference and I canceled the connection of DS90C401. The output was still wrong. I/Q could not track the tested signal's amplitude or phase. 

    I am really upset about its application because I have spent plenty of time to study it. But the outcome was always filled with errors.

    Best wishes

Children