help me with homework

Discussion in 'Homework Help' started by mo332, Nov 8, 2011.

  1. mo332

    Thread Starter New Member

    Nov 8, 2011
    Please can someone help me on this problem. I need to know where to start, I know I need to use a MOSFET​

    Design, build and test an AC coupled amplifier powered from a 12V supply with the
    following specification.​

    Input voltage: 100mV
    · ​

    Covers the audio frequency range: at most 50Hz to at least 10kHz
    · ​

    Gain: 24±2 dB (gain should be flat over the specified frequency range)
    · ​

    Output should not be inverted
    · ​

    Input impedance: >1.2 MW
    · Output impedance: <180 W
    · No resistors <220 Ohms to be used​
    · No parallel resistors on transistor output stages
  2. Georacer


    Nov 25, 2009
    Greetings! And welcome to AAC!

    Your post, originally found here (, has been moved into its own thread, where it will draw more responses.

    Please refrain from "hijacking" existing threads with tangent or off-topic questions. You can create new threads for new questions using the "New Thread" button on the upper left of the page.

    Also, the Homework Help section asks that you post up the work you have done so far, so we can see it and find where you went wrong, or suggest better approaches. We will not do all your work for you.

    If you are in doubt about how to structure your post and what to include please read this thread:

    Thank you.
  3. JDT

    Well-Known Member

    Feb 12, 2009
    I was going to suggest a "common source" amplifier (which you could Google). But this will give an inverted output.

    If you want voltage gain, high input impedance, low output impedance and non-inverting you will need more than one transistor.

    You could use two common source amplifier stages, the first one feeding the second one. Each one inverts, therefore the complete circuit does not. To accurately control the gain you need to use overall negative feedback.

    Have you been given any more clues in your course notes?