How to design telephone amplifier with op amp and filters

Discussion in 'Homework Help' started by kungfupanda1947, Dec 2, 2009.

  1. kungfupanda1947

    Thread Starter New Member

    Dec 2, 2009
    Use op amp and filter circuits to build a telephone amplifier from 300 to 4k Hz with again of 50 (or -50). Check points: 1) -3dB frequencies at 300 Hz and 4 kHz. 2) voltage gain of 50 in mid-band.

    Please help to solve the problem above. I have got a start and think that to design this I have to cascade high pass and low pass to form band pass to get desired frequencies and then cascade it to a op-amp(ua741) to get gain. I kind of know the equations but still please help me solve the problem and let me know if my start is a correct start or not.
  2. mik3

    Senior Member

    Feb 4, 2008
  3. Audioguru


    Dec 20, 2007
    You need highpass and lowpass filters, not a bandpass filter.
    The bandpass filter is used for a narrow range of frequencies.

    Use butterworth second-order or third-order Sallen and Key filter circuits for sharp cutoffs.