ADA4817-1/2

Hello, 

I am looking for a buffer (Analog) with the following requirements: 

1) Input voltage range: 0V to 0.9V 

2) Fq: ~100MHz to 200MHz 

3) Iq, Noise: We don't really care about it 

4) VDD: We can provide any VDD between 0.9V to 3.3V (Or may be even higher if needed)

5) Should have very (very) low input capacitance. Kind of main requirement for this buffer. (May be less than 1pF?? I know its difficult to get it) If input doesn't have ESD protection, it will work for us.

6) Input is single ended 

 

I searched the website and found ADA4817-1/2. Is this the closest product for our specs or do you suggest some thing else?

 

Thank you!

  • 0
    •  Analog Employees 
    on Jul 18, 2018 5:43 PM

    Hi Premsagar,

    ADA4817 would work but it requires a minimum Vs=5V. The closest fit for your application is LTC6268. Let me know if this works. Also, could you share what your application is?

    Regards,

    Jino

  • 0
    •  Analog Employees 
    on Jul 19, 2018 5:59 PM

    Hi,

    5.5 V is the Abs Max Supply Voltage for LTC6268. This doesn't mean that you have to power the part at 5.5V. The Abs Max Ratings specifies parameters where the part is expected to operate before potential permanent damage. So to answer your concern regarding negative supply, NO you don't need a negative supply as long as your inputs are unipolar since the part can accept inputs down to 0V.

    On your first posted questions, you mentioned these requirements:

    4) VDD: We can provide any VDD between 0.9V to 3.3V (Or maybe even higher if needed) --- LTC6268 is specified to operate with supply Voltage Range of 3.1 V to 5.25 V. This means that you can power it with Vs=3.3V and the expected performance are defined on pages 5 and 6 of the datasheet.

    1) Input voltage range: 0V to 0.9V  --- When powered with Vs=3.3V, the amplifier has an Input Voltage Range of 0 to 2.8V. Make sure that your input is within this range to avoid clipping and/or distortion due to IVR limitations.

    5) Should have very (very) low input capacitance. Kind of the main requirement for this buffer. (Maybe less than 1pF?? I know its difficult to get it) If the input doesn't have ESD protection, it will work for us. --- Cdiff and Ccm of LTC6268 are 0.1 pF and 0.45 pF respectively.

     

    Regards,

    Jino

  • LTC6268

    <https://ez.analog.com/external-link.jspa?url=http%3A%2F%2Fwww.analog.com%2Fmedia%2Fen%2Ftechnical-documentation%2Fdata-sheets%2F62689f.pdf>

    looks

    good for our application.

    In the data sheet it says " Supply Voltage V+ to V–

    ...........................................5.5V ". Correct me if I am wrong

    here: the potential difference between positive power supply to negative

    power supply pin should be 5.5V right..?? In our PCB we are planning not to

    use any negative power supply. If that is the case, does this mean that we

    have to supply 5.5V to V+ and ground the V- pin? (Worst case, we are ok to

    supply a negative voltage to the PCB via power supply unit as well, but we

    just want to avoid it if we can)

    We have a test chip here and we want to test few internal nodes. We have a

    test mux circuit in the chip which will give access to few internal nodes

    (analog circuit inside the chip) and we want to hook it up to a connector

    and analyze the voltage. In between our chip and the connector (sitting at

    the edge of the PCB), we need buffers because of the long trace.

    On Wed, Jul 18, 2018 at 6:44 PM JinoL <

  • Thanks for the suggestion and feedback. It was really helpful! We will

    order this product once we finalize on the other stuffs on our PCB.

    Thanks &  Regards,

    Premsagar

    On Thu, Jul 19, 2018 at 7:00 PM JinoL <