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make it clearly beta and betaeff

imagesensor123

 Hi,

    these days i am doing some circuit simulation, and i got confused by beta and betaeff? according to the simple hand calculation equation id=1/2uCoxW/L(Vgs-Vth)^2 or id=1/2beta(Vgs-Vth)^2  or the others. and after simultion, i use the result->print->operation point and i found a betaeff parameter, i think it shold be same with beta, but after calculation id, i found the id(betaeff) is just a half of the id(beta), and how do you calculate the drain current id in saturation region?

Parents

  • Hi Andrew,
    yes, i talk about the transistor in saturation mode, and i use the bsim3v3 model. i looked through the document(Spectemod), but i just found they mentioned betaeff, not give the detail explanation.the reason why i calculate the drain current(nmos saturation mode) is that i am designing a current source(current mirror), i found i can't get the copy current in the output branch, so i want to calculate it by hand , and check out my design fault. and i searched betaeff on the internet, most people talk about beta, not the betaeff in the spectre result, so comes this confuse.

    thanks,
    zfeng

Reply

  • Hi Andrew,
    yes, i talk about the transistor in saturation mode, and i use the bsim3v3 model. i looked through the document(Spectemod), but i just found they mentioned betaeff, not give the detail explanation.the reason why i calculate the drain current(nmos saturation mode) is that i am designing a current source(current mirror), i found i can't get the copy current in the output branch, so i want to calculate it by hand , and check out my design fault. and i searched betaeff on the internet, most people talk about beta, not the betaeff in the spectre result, so comes this confuse.

    thanks,
    zfeng

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