Connecting the bulk of a PMOS.. (CMOS complex function)

Discussion in 'Homework Help' started by wiz0r, Apr 22, 2010.

  1. wiz0r

    Thread Starter Active Member

    May 2, 2008

    I have to simulate using SPICE a function AB + BC + AC.. and I have various questions. Regarding the PMOS network.. does the bulk of all of the PMOS transistors be connected to Vdd?

    Hopefully, someone can help soon. I have other questions, but I need to get this straight first. Any help is appreciated.
  2. Ghar

    Active Member

    Mar 8, 2010
    Yes, PMOS substrate goes to Vdd.

    PMOS means P-type channel, which means the substrate is N. The channel is substrate being inverted. The source/drain are P-type.

    Remember that a diode is a PN junction, with forward current through P to N.
    You need that junction reverse biased, which means putting Vdd on the N-type substrate and hopefully the P-type drain/source will be either Vdd or lower.