Cascading AD8335 amplifiers

Hello,

  I have acquired AD8335EVAL module and I would like to cascade the 4 amplifiers in order to increase gain.

  What would be the recommendation in order to change from Differential to single input that is how the board is configured?

 Thank you in advance for your feedback on this matter.

br

Gabriel

  • 0
    •  Analog Employees 
    on May 22, 2018 3:51 AM over 2 years ago

    Hi Gabriel,

    If you are referring to the first channel/amplifier input in the cascade, you could configure your inputs PIPx and PMDx pins like in Figure 54 of page 16 of AD8335 datasheet. PIPx pin has capacitor, resistor and voltage source in series and PMDx has capacitor connected to the ground.

  • Hi 

    Thanks for the quick reply.

    I was referring to channel 1 output to channel 2 input and ch2 output to ch3 input and ch3 output to ch4 input. 

    I do not mind checking being single ended but in order to couple ch1 output (diff) to ch2 input a change in Config is in order I presume. That change or mod is my actual question 

    Thank you again 

    Br 

    Gabriel 

  • 0
    •  Analog Employees 
    on May 23, 2018 6:36 AM over 2 years ago

    Hi Gabriel,

    Let me try to check this first on LTSpice to see if what configuration is possible.

  • 0
    •  Analog Employees 
    on May 29, 2018 4:30 PM over 2 years ago

    Hi Gabriel,

    To change the differential outputs to single ended, you could use a transformer as a balun, such as those shown on the Test Circuits page in the datasheet (Rev B page 15).  Keep in mind that the output stage needs a load of 500 Ohms or greater.

    Can you let me know what your application is?

    Cheers,

    George

  • HiThanks for the reply.Unfortunately those balun are too expensive compared to, let's say lt1567 alternative.Application is an hydrophone amplifier.  Signal source level is extremely low, thus the need for high gain.Thanks againGabriel 

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    Re: Cascading AD8335 amplifiers

    reply from George.Kadziolka in Differential Amplifiers - View the full discussion

    Hi Gabriel,

    To change the differential outputs to single ended, you could use a transformer as a balun, such as those shown on the Test Circuits page in the datasheet (Rev B page 15).  Keep in mind that the output stage needs a load of 500 Ohms or greater.

     

    Can you let me know what your application is?

     

    Cheers,

    George

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