Note: 1. Op Points numbered from Top Left of the Curve
2. Voltage values are assumed to demonstrate the validity of the equations
For NMOS: For PMOS:
Vgs = Vin – 0 (Gnd) Vsg = 5 (Vdd) – Vin
Vds = Vout – 0 (Gnd) Vsd = 5 (Vdd) – Vout
Vt = A typical 0.7 V Vt = A typical – 0.7 V
Op Point 1: Vin = 0V, Vout = 5V
For NMOS: For PMOS:
Vgs < Vt Vsd < Vsg – |Vt|
Therefore OFF Therefore LINEAR
Op Point 2: Vin = 2V, Vout = 4.5V
For NMOS: For PMOS:
Vds > Vgs – Vt Vsd < Vsg – |Vt|
Therefore SATURATION Therefore LINEAR
Op Point 3: Vin = 2.5V, Vout = 2.5V
For NMOS: For PMOS:
Vds > Vgs – Vt Vsd > Vsg – |Vt|
Therefore SATURATION Therefore SATURATION
Op Point 4: Vin = 3V, Vout = 1V
For NMOS: For PMOS:
Vds < Vgs -Vt Vsd > Vsg – |Vt|
Therefore LINEAR Therefore SATURATION
Op Point 5: Vin = 5V, Vout = 0V
For NMOS: For PMOS:
Vds < Vgs -Vt Vsg < |Vt|
Therefore LINEAR Therefore OFF
PS: There would be another post about the operating regions of NMOS and PMOS as stand-alone devices.