high bandwidth op amp with same other feature as LM 741

Discussion in 'General Electronics Chat' started by ef_manu, Jun 6, 2013.

  1. ef_manu

    Thread Starter New Member

    Jun 6, 2013

    I am trying to create an "auto balancing bridge" for impedance measurement in the range of 1 MHz to 10 MHz. For that purpose I need an op-amp . Can anyone suggest? I tried with LM 741 for low frequency,it is working properly. I tried with AD 8055 instead of LM 741 for high frequency impedance measurement, I am not getting any output.. Is any gain restriction for AD 8055 ? So I need an op amp with all same features except band width, need high band width upto some 300 MHz. ..

    Regards ,

  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    Can you show a your circuit diagram?
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
    Is that all?

    Please show schematic or what you are trying to do.

    As far as I know, no single op amp can come anywhere near that. The really wide band op-amps used for pre amps like NE5532 have bandwidths of around 10 MHz.

    To understand how difficult it is to get to 300 MHz: oscilloscops have horizontal amp/drivers that set their bandwidth. The cheaper ones are 10 MHz, the best in the world like Tektronix 7904 drivers can get to about 300 MHz. That requires a very fast, multiple stage design with a lot of tweaking. 300MHz is not easy.
  4. RichardO

    Well-Known Member

    May 4, 2013
    Some general comments:

    The AD8055 has a total power supply limit of 13.2 volts and is specified at +/- 5 volts.

    The 300 MHz specification for the AD8055 is at a gain of 1 and only at small output amplitudes. More gain in your circuit will result in less bandwidth.

    Output amplitudes are limited by the slew rate of the amplifier -- typically 1400 volts per microsecond for the AD8055.

    Merely unplugging the LM741 and plugging in the AD8055 is highly unlikely to work because of component values, stray capacitances and wiring effects at the much higher speeds the AD8055 is capable of.

    Having said the above, what do you mean by " I am not getting any output". We need more specific information to be able to help with your specific problem. A schematic and pictures of how the circuit is built are essential.