how to use ideal switches?

Discussion in 'The Projects Forum' started by Kit_Leong, Dec 7, 2010.

  1. Kit_Leong

    Thread Starter New Member

    Dec 4, 2010

    I am currently trying to design a modulator/demodulator for my chopper stabilized bandgap reference circuit.Attached is a picture of the switches required for the modulator and the demodulator.Some journals suggest the use of transistors as these switches.I am using mentor graphics for my simulation.However all my 4 transistors are always in the subthreshold mode even after I tried modifying to width and length ratio of the transistors.Does anyone know how else I can saturate my transistors?

    Alternatively I am trying to use ideal switches instead,but mentor graphics does not have such ideal switches to implement,so I have to search myself a spice file to include it manually into my circuit.Does anyone know where I can find such an ideal switch spice file?

    As you can see in the diagram,each of these switches are driven by a clock signal,signal 1 and signal 2.These 2 signals are supposed to be a square wave non overlapping clock signal.

    Thank you.
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    I don't know if we have any Mentor Graphics users here. Run your sims in LTspice, and you can get plenty of expert advice here. LTspice is very good, and it's free!