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Clean Biasing options for LNA

Discussion in 'Electronic Design' started by [email protected], Oct 21, 2006.

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  1. Guest

    Hi everyone,.
    I have designed a low noise amplifier which needs + 4.4 volts and -5
    volts (~10mAs) for biasing purposes. Uptill now on bench testings i was
    using switching DC power supplies. However now i want to integrate it
    with my datasystem and wondering which way i can bias my amplifier,
    keeping noise from the bias lines minimum. I have put bunch of
    bypassing capacitors close to the circuit.
    Should i just get some batteries & use resistors in series or if there
    are clean regulated DC OEM type power supplies i can mount in a small
  2. colin

    colin Guest

    You might want to use a combination of feedthrough capacitors ferrite beads
    and or RC/LC filters on the power supply lines fed from any available
    suitable power lines, I assume it will be in its own screened enclosure,
    small sot23 regulators are helpfull too if theres lower frequency
    noise/ripple on the lines wich might cuase a problem, however I dont seem to
    be able to find any sot23 -5 regulaters last time I looked form my usual
    supplier anyway.

    Colin =^.^=
  3. vasile

    vasile Guest

    Usually any LNA *MUST* be supplied from a linear clean regulator (or a
    ultra low noise DC switching supply as those from Linear Technologies).
    There are a bunch of LDO regulators in SC70 or SOT23-5 packages (at
    Digikey for example). Search for LDO at National and Maxim.
    Filtering will not help as long the noise may come on the ground from a
    nasty switching DC supply.

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