A bandgap cell runs its two transistors at a current-density ratio

PHYSICS · Multi-part · Fermi University Physics · Electronics, Instrumentation & Communication · Semiconductor devices and analogue circuits · Semiconductor devices and analogue circuits

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Problem

n = 16

. At

300\,\mathrm{K}

, where

V_T = 25.9\,\mathrm{mV}

, the transistor whose

V_{BE}

enters the sum has

V_{BE} = 0.62\,\mathrm{V}

, falling at

1.9\,\mathrm{mV\,K^{-1}}

. ((a)) Find

\Delta V_{BE}

and its temperature slope. ((b)) Find the multiple

K

that cancels the first-order drift of

V_{\rm ref} = V_{BE} + K\Delta V_{BE}

. ((c)) Find

V_{\rm ref}

, and compare it with

V_{BE}

extrapolated along its straight line to

T = 0

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