circuit_cook
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Posts: 25
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Hi, I have a question about bandgap voltage, I am porting a bandgap design which is a typical Brokaw bandgap, from 45nm to 40nm, but the bipolar model, (Tnf1, tnf2) changed a lot, and Vbe extraplated at absolute 0T shifted down 10mV from 45nm to 40nm in my simulation. The bandgap voltage output in 45nm is 1.23V, while after I adjust the R ratio (minimum change desired) to achieve zero TC in 40nm, I get 1.20V for 40nm. But I was told both zero TC and the 1.23V is important to keep the same. Because the bandgap is used as reference in AD,etc. Is that possible I can get the 1.23V just by adjusting the bandgap IPTAT current, to get the VBE TC like in 45nm? the current change would be too much, and it would require other opa change, since TC(vbe) =f(Vbe0), and Vbe0=Vtln(Ic). Please give me some advice.
Thank you. JS
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