MOSFET Transistors
Figure 6-2 illustrates an equivalent circuit for the n-channel MOSFET transistor. The p-channel MOSFET transistor is treated similarly, but the polarities of the involved voltages are reversed.
Figure 6-2: A circuit for the MOSFET transistor.
The following equations are used to compute the relations between currents and voltages in the circuit.
There are also several capacitances between the terminals
The model parameters are as follows:
Table 6-2: MOSFET Transistor Model Parameters.
Parameter
Default
Description
 CBD
0 F/m
Bulk-drain zero-bias capacitance
 CGDO
0 F/m
Gate-drain overlap capacitance
 CGSO
0 F/m
Gate-source overlap capacitance
 FC
0.5
Capacitance factor
 IS
10-13 A
Bulk junction saturation current
 KP
2×10-5 A/V2
Transconductance parameter
 L
50×10-6 m
Gate length
 MJ
0.5
Bulk junction grading coefficient
 N
1
Bulk junction ideality factor
 PB
0.75 V
Bulk junction potential
 RB
0 Ω
Bulk resistance
 RD
0 Ω
Drain resistance
 RDS
Inf (Ω)
Drain–source resistance
 RG
0 Ω
Gate resistance
 RS
0 Ω
Source resistance
 TNOM
298.15 K
Device temperature
 VTO
0 V
Zero-bias threshold voltage
 W
50×10-6 m
Gate width
 Γ (GAMMA)
1 V0.5
Bulk threshold parameter
 Φ (PHI)
0.5 V
Surface potential
 Λ (LAMBDA)
0 1/V
Channel-length modulation