op-amp design

Discussion in 'General Electronics Chat' started by surreyian, Oct 26, 2004.

  1. surreyian

    Thread Starter New Member

    Oct 26, 2004
    Hello all,

    I'm currently designing a op-amp, but I had some problems.

    My op-amp is made up of pnp differential amplifer, using active load and current source using current mirror, follow by a CE circuit, and CC. The output is tapped from CC configuration.

    What difference does it make if the differential amplifier is configuration using NPN? What are the pros and cons using them?

    Initial design was to use only 1 power supply, +10V. In the later stage of the design, I was told to use 2 supply, +5V and -5V. What are the advantges of using dual supply? Does it increase the input range?

    Simulted result give a open loop gain of 850. Individually the differential amplifier has a gain of 2000. How can we determine the overall gain (open loop gain) by calculation? I try to determine the gain of each stage indivdually, then multiply them together, but it doesnt telly with the simulated results.

    How can we determing the output and input dynamic range?

    How can we determine the common mode gain?

    What is miller effect?
  2. mozikluv

    AAC Fanatic!

    Jan 22, 2004

    are you trying to build an audio power amp?

    dont you have electronic books that discusses in detail of miller effect?

    just to give you an idea, miller effect usually occur in the AC behavior of a transistor amplifier circuit when there is simultaneous switching of both ends of a cap and as a result the effective capacitance is modified like gain+1 times as big as it actually is. pls. don't ask me to further elaborate on this, it will take a book to fully explain this.

    i don't see any major difference whether you use PNP or NPN in a diff. amp. i would rather say it's a matter of preference.

    your supply has nothing to do with your input range.

    your I/O range will depend on the parameters you set

    hope other members would add more inputs ;)
  3. singhak


    Oct 18, 2004