BSIM3v3.2.2 MOSFET Model - The University of Texas at Dallas
BSIM3v3.2.2 MOSFET Model - The University of Texas at Dallas
BSIM3v3.2.2 MOSFET Model - The University of Texas at Dallas
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Methodology for Intrinsic Capacitance <strong>Model</strong>ing<strong>The</strong> accumul<strong>at</strong>ion charge and the substr<strong>at</strong>e charge are associ<strong>at</strong>ed with thesubstr<strong>at</strong>e while the channel charge comes from the source and drainterminals( )⎧Q =− Q + Q + Q⎪⎨Qb = Qacc + Qsub⎪⎩Qinv = Qs + Qdg sub inv acc(4.3.1)<strong>The</strong> substr<strong>at</strong>e charge can be divided into two components - the substr<strong>at</strong>echarge <strong>at</strong> zero source-drain bias (Q sub0 ), which is a function <strong>of</strong> g<strong>at</strong>e tosubstr<strong>at</strong>e bias, and the additional non-uniform substr<strong>at</strong>e charge in thepresence <strong>of</strong> a drain bias (δQ sub ). Q g now becomes( )Q =− Q + Q + Q + Qg inv acc sub0 δsub(4.3.2)<strong>The</strong> total charge is computed by integr<strong>at</strong>ing the charge along the channel.<strong>The</strong> threshold voltage along the channel is modified due to the nonuniformsubstr<strong>at</strong>e charge byth( y) = V th( 0) + ( A bulk − ) V yV 1(4.3.3)⎧⎪Qc= W⎪⎪⎨Qg= W⎪⎪⎪Qb= W⎪⎩Lactive∫Lactive∫Lactive∫q dy = −Wactive cactive ox0 0q dy = Wactive g active ox0 0q dy = −WCCCactive bactive ox0 0LLactive∫( Vgt− AbulkVy)active∫( Vgt+ Vth−VFB− Φs−Vy)Ldydyactive∫( Vth−VFB− Φs+ ( Abulk−1)Vy)dy(4.3.4)<strong>BSIM3v3.2.2</strong> Manual Copyright © 1999 UC Berkeley 4-5
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