Multistage amplifier power question

Discussion in 'Homework Help' started by athos, Nov 21, 2008.

  1. athos

    Thread Starter New Member

    Nov 21, 2008
    Hi everybody,

    Thanks for taking the time. I have to design a multistage amplifier (ER-CE) with specification that "total power consumption must be less than or equal to 175mW".

    What is included in the Total power consumption? Is it the
    first stage ER [transistor power (dc) and the stage load power (ac)] added with
    second stage CE[[transistor power (dc) and the stage load power (ac)]

    or only the dc power values should be considered?

  2. mik3

    Senior Member

    Feb 4, 2008
    If you are talking about the quiescent power dissipation then you have to consider only the DC values of the two stages. However, if you want the total power dissipation you need to consider both DC and AC values of the two stages. I guess is the second case I mentioned, better to ask your teacher.
  3. athos

    Thread Starter New Member

    Nov 21, 2008
    Thanks. I sent her an email and do not have an answer so far. Thanks for suggestion.
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    Surely "total power" will be the power drawn from the battery?

    Some of this is supplied to the load and some is wasted in circuit inefficiency.

    175 milliwatts is enough to power a small loudpeaker or earphones as found in small portable battery powered radios/MP3 players/dictaphone units/mobile phone etc etc.

    I am assuming an audio amp is to be designed, not an RF one, which is a different kettle of fish?

    Here the max is usually 100milliwatts for mobile phone/wifi router etc.