CMOS operational amplifier design

Discussion in 'Homework Help' started by Mohamad, May 25, 2010.

  1. Mohamad

    Thread Starter New Member

    Jun 16, 2007
    Hello Friends,

    I'm taking an electronics course this semester and i got to do a small homework project like for this course..

    the amplifier is a differential input single ended cmos op amp

    it has to meet the following specs as in the figure


    I should use a positive +VDD/2 supply and a negative –VDD/2 supply only.

    The requirement to have VOS = 0 V means that there should be no differential mode offset; for a 0 V differential input and a common-mode input at the midpoint of the common-mode input range, the output should be 0 V under nominal supply conditions.

    I am free to choose the midpoint of the common mode input range.

    The available components are: NMOS transistors, PMOS transistors and resistors. Ideal sources can only be used to generate the supply voltages, not to generate bias currents.

    Device Models

    The device models are encapsulated in a sub-circuit; use:

    x1 d g s b nmos w=10u l=0.13u
    x2 d g s b pmos w=10u l=0.13u

    The sub-circuit definitions are as follows:

    .subckt nmos d g s b params: w=10u l=0.13u
    m0 d g s b nmos_internal w={w} l={l}
    .model nmos_internal
    + nmos level=1 kp=500u vto=0.3 gamma=0.2 phi=0.6
    + ld=0.025u
    + lambda={0.2*exp(0.13u/{l})/exp(1)}

    .subckt pmos d g s b params: w=10u l=0.13u
    m0 d g s b pmos_internal w={w} l={l}
    .model pmos_internal
    + pmos level=1 kp=120u vto=-0.3 gamma=0.2 phi=0.6
    + ld=0.025u
    + lambda={0.15*exp(0.13u/{l})/exp(1)}



    i'm finding this very difficult to achieve

    i tried something on a draft and is as follows:



    am i close to something ??? any suggestions ?? how to assign a value for every transistor ?

    how to complete the schematic ?? and examples close to what i'm going to do

    thank you in advance
  2. aimiazri

    New Member

    Jan 7, 2010
    i dont really know act.. but, i have read it.. try to get reference from book CMOS Analog Circuit Design. Philip E. Allen & Douglas R Holberg..