Post Go back to editing

ad8338 no signal and square wave (beginner)

Category: Hardware
Product Number: AD8338

Hello , im beginer in alectronics , and i designed a PCB using an AD8338

I'm using it in single ended without the AGC, and when i try to analyse the output of the VGA using an oscilloscope i dont have any signal . for some reason the ad8338 seem to produce a square wave that change in width when changing the gain (around mid-gain) at max and min gain, I got nothing at all (also append when there is no signal in input) could i have some advice of what i am missing or why i get this behaviour , i cant find a way to get any signal trough. Thanks in advance and sorry if there is some obvious mistake.

Parents
  • Hi  ,

    I noticed that you want to use AD8338 with a single ended input and single ended output, is that right?

    Configuring the AD8338 with a single ended input requires an amplifier that can convert single-ended signal to differential such as AD4940-1 and the unused pin, INMR, must be tied to VREF that can affect the gain. With that, the signals are not prone to distortion and gain is at optimum.

    Configuring the AD8338 with a single-ended makes one side of the output equivalent to (Vout/2)+Vref based on figure 41 of the datasheet. 

    If you want to maintain the full-scale, you may want to use a follower amplifier such as AD8130 in order to convert a differential signal to single-ended signal.

    I hope this information helps. 

    Regards,

    Mae

Reply
  • Hi  ,

    I noticed that you want to use AD8338 with a single ended input and single ended output, is that right?

    Configuring the AD8338 with a single ended input requires an amplifier that can convert single-ended signal to differential such as AD4940-1 and the unused pin, INMR, must be tied to VREF that can affect the gain. With that, the signals are not prone to distortion and gain is at optimum.

    Configuring the AD8338 with a single-ended makes one side of the output equivalent to (Vout/2)+Vref based on figure 41 of the datasheet. 

    If you want to maintain the full-scale, you may want to use a follower amplifier such as AD8130 in order to convert a differential signal to single-ended signal.

    I hope this information helps. 

    Regards,

    Mae

Children
No Data