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DC Coupling  ADL5565

I am considering DC coupling the ADL5565 inputs, which appears to be more intended for AC coupling and all examples show AC.

I suspect Vicm needs to equal Vocm  for optimum RF performance?  when DC coupling

I do not see DC offset directly specified but the output offset appears large … -100 to 20 mV.

Given this rather than try to drive Vicm directly I would likely try to sense it and adjust Vocm to force Vicm to ground in a low frequency offset nulling feedback loop…

Any ideas help or data on DC coupling will be appreciated.

Thanks

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  • Hi David,

                     The default common mode level, input and output, is VCC/2. It is adjustable within a certain range. The input common mode range for a 5 V supply is: 1.2 V to 3.8 V. The output common mode range comon mode range is: 1.4 V  to 1.3 V.  For a 3.3V supply the input common mode range is: 1.2 V to 2 V and the output common mode range is 1.4 V t o 1.8 V.  For proper operation the common mode voltages must be kept within the specified operation range.

  • Hi Jim,

    Back in 2013, you noted above that the ADL5565 output CM voltage range is 1.4V to 1.3V! with 5V single supply? That must be a typo.

    I see VCOM going from 1.4V to 3.0V in Figure 20 shown below. I'm going to assume that the higher end is 3.0V and your statement is a typo:

    Regards,

    Hooman

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  • Hi Jim,

    Back in 2013, you noted above that the ADL5565 output CM voltage range is 1.4V to 1.3V! with 5V single supply? That must be a typo.

    I see VCOM going from 1.4V to 3.0V in Figure 20 shown below. I'm going to assume that the higher end is 3.0V and your statement is a typo:

    Regards,

    Hooman

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