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M — MOSFET

The MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a four-terminal semiconductor device widely used in digital and analog circuits.

Syntax

M<name> <drain> <gate> <source> <bulk> <model_name> [L=<length>] [W=<width>] [M=<m>] [IC=<vds>[,<vgs>[,<vbs>]]] [OFF]
Parameter Description
drain Drain node
gate Gate node
source Source node
bulk Bulk/substrate node
model_name Name of a .MODEL NMOS(...) or .MODEL PMOS(...) definition
L=length Channel length
W=width Channel width
M=m Multiplier (parallel devices)
IC=vds[,vgs[,vbs]] Initial junction voltages for UIC
OFF Initial guess: device is off

Examples

M1 OUT IN 0 0 NMOS_MODEL L=1u W=10u
M2 OUT IN VDD VDD PMOS_MODEL L=0.5u W=20u
M3 D G S B my_nmos L=0.18u W=2u M=4

Model Definition

NMOS

.MODEL NMOS_MODEL NMOS(VTO=0.7 KP=110u GAMMA=0.4 LAMBDA=0.04 PHI=0.65)

PMOS

.MODEL PMOS_MODEL PMOS(VTO=-0.7 KP=50u GAMMA=0.57 LAMBDA=0.05 PHI=0.65)

Common Model Parameters

Parameter Description
VTO Threshold voltage
KP Transconductance parameter
GAMMA Body-effect parameter
LAMBDA Channel-length modulation
PHI Surface potential
TOX Oxide thickness
CBD Bulk-drain junction capacitance
CBS Bulk-source junction capacitance

Model Levels

SpiceSharpParser supports MOS Level 1 (Shichman-Hodges), Level 2, and Level 3 models, automatically selected based on the LEVEL parameter:

.MODEL my_nmos NMOS(LEVEL=1 VTO=0.7 KP=110u)
.MODEL my_nmos2 NMOS(LEVEL=2 VTO=0.7 KP=110u)
.MODEL my_nmos3 NMOS(LEVEL=3 VTO=0.7 KP=110u)

Typical Usage

CMOS inverter
VDD VDD 0 3.3
VIN IN 0 PULSE(0 3.3 0 1n 1n 10n 20n)
M1 OUT IN VDD VDD PMOS_MODEL L=0.5u W=2u
M2 OUT IN 0 0 NMOS_MODEL L=0.5u W=1u
.MODEL PMOS_MODEL PMOS(VTO=-0.7 KP=50u)
.MODEL NMOS_MODEL NMOS(VTO=0.7 KP=110u)
.TRAN 0.1n 40n
.SAVE V(OUT) V(IN)
.END