HELP!! VCO design

Discussion in 'Homework Help' started by jjohn, Apr 6, 2009.

  1. jjohn

    Thread Starter Member

    Feb 18, 2009
    13
    0
    Dear All,
    I have attached the three diagram of VCO .No.1 is VCO for NMOS only tailed bias VCO. No2 is differetial VCO . No3. is Oscillator from cross couple inverter.

    Question: why they use 4 terminal NMOS as varactor ??what is the advantage of this .?

    Question :In No.3 , I know the top PMOS is cross coupled and what is the function of NMOS below. It look like MEMORY circuit DRAM .Why he choose that layout and advantage?

    Thanks..
     
  2. jjohn

    Thread Starter Member

    Feb 18, 2009
    13
    0
    VCO-3 is same as VCO-4.
     
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