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2ndclass



Posts: 182
Joined: June 2006

(Permalink) Posted: Oct. 09 2006,06:25   

Still here, Dave?  Thanks for continuing the conversation.

   
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Any simulation that incorporates propagation delay is not strictly boolean anymore.

Boolean means that there are two possible states.  Do propagation delays add more possible states?

   
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Moreover, the mosfets only operate in two states, on or off.

Interesting.  And here I thought that MOSFETs had three operating modes, each continuous and roughly linear, making MOSFETs no more boolean than BJTs or JFETs.  But you're the genius.

   
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Unlike older silicon transistors, mosfets ...

And what are MOSFETs made of?

   
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...mosfets require no resistive or capacitive elements.

More accurately, it's complementary logic that requires no resistors.  MOSFETs aren't the only transistors that can be used in complementary logic, and MOSFETs require pull-up or pull-down resistors if they're not used in a complementary configuration.

And using MOSFETs rarely eliminates the need for capacitors.  More often, their inherent capacitance is a hindrance rather than a help.

   
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I had assumed that I was talking with people who were sufficiently knowledgable to recognize that the difference between modeling a CMOS processor at the transistor level and the gate level is a quibble because the individual logic gates are composed of just a few simple on/off mosfet (transistor) switches.

Like most EEs, I used SPICE, which most definitely does not treat MOSFETs as on/off switches.  What transistor modelling tool did you use?

Oh, I almost forgot to give you an opportunity to solve a problem.  Here's one, and it's about as easy as it gets:  Given an NMOS transistor with I_dss = 16mA and V_p = -4V, what is the gate-to-source voltage required to establish I_d = 32mA?

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"I wasn't aware that classical physics had established a position on whether intelligent agents exercising free were constrained by 2LOT into increasing entropy." -DaveScot

  
  29999 replies since Jan. 16 2006,11:43 < Next Oldest | Next Newest >  

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