3.4.3 Source Side Potential and Charge Calculation
The core model calculation at the source side is shown below:
qdep=nVtmqdep(3.271)
vch=0.0+ΔVt,QM(3.272)
Here 0.0 refers to the quasi-fermi potential at the source side
If BULKMOD≠0 then,
T1=hypsmooth(2.0⋅ϕB+vch−ves,1.0)(3.273)
T3=−(2.0⋅nVtmK1_t)⋅(√T1−√2.0⋅ϕB)(3.274)
T0=−qdep−T3+vth_fixed_factor_sub+QMFACTOR⋅(−qdep)2/3(3.275)
T1=−qdep−T3+vth_fixed_factor_SI(3.276)
For the terms vth fixed factor sub and vth fixed factor SI, please see the Verilog-A source code file (bsim-
cmg body.include)
If BULKMOD=0 then
T0=−qdep−T3+vth_fixed_factor_sub+QMFACTOR⋅(−qdep)2/3(3.277)
T1=−qdep+vth_fixed_factor_SI(3.278)
T2=nVtmvgsbeff−vch(3.279)
F0=−T2+T1(3.280)
T3=0.5⋅(T2−T0)(3.281)
qm=exp(T3)(3.282)
If qm>10−7 then
T7=ln(1+qm)(3.283)
qm=2.0⋅(1.0−√1.0+T7⋅T7)(3.284)
T8=(qm⋅alpha_UFCM+qdep)⋅rc(3.285)
T4=exp(T8)−T8−1.0T8(3.286)
T5=T8⋅T4(3.287)
e0=F0−qm+ln(−qm)+ln(T5)+QMFACTOR⋅[−(qm+qdep)]2/3(3.288)
e1=−1+qm1+(T8−T4−12)⋅rc−32⋅QMFACTOR⋅[−(qm+qdep)]−1/3(3.289)
e2=qm⋅qm−1−92⋅QMFACTOR⋅[−(qm+qdep)]−4/3(3.290)
qm=qm−(e1e0)⋅(1.0+2.0⋅e1⋅e1e2⋅e2)(3.291)
T8=(qm⋅alpha_UFCM+qdep)⋅rc(3.292)
T4=exp(T8)−T8−1.0T8(3.293)
T5=T8⋅T4(3.294)
e0=F0−qm+ln(−qm)+ln(T5)+QMFACTOR⋅[−(qm+qdep)]2/3(3.295)
e1=−1+qm1+(T8−T4−12)⋅rc−32⋅QMFACTOR⋅[−(qm+qdep)]−1/3(3.296)
e2=qm⋅qm−1−92⋅QMFACTOR⋅[−(qm+qdep)]−4/3(3.297)
qm=qm−(e1e0)⋅(1.0+2.0⋅e1⋅e1e2⋅e2)(3.298)
If qm≤10−7 then
qm=−qm⋅qm(3.299)
qis=−qm⋅nVtm(3.300)
ψs=Vgsfbeff−qis(3.301)
Eeffs=10−8⋅(ϵratio⋅EOTqbs+η⋅qis)(3.302)