1
Transistor capacitances
LECTURE 11
• transcapacitance
• intrinsic capacitance and oxide capacitance
• extrinsic FET capacitances
• quantum capacitance
2
Sec. 12.2.1
MOSFET equivalent circuit
Recall this expression for capacitances in a MOSFET
It can be represented by this equivalent circuit
What is Cm ?
3
Sec. 12.2.1
Transcapacitance
Consider 2 cases to
illustrate the meaning of
transcapacitance:
What does each circuit represent?
4
Sec. 12.2.1
Intrinsic capacitances and Cox
What are the reasons for these trends?
5
Sec. 12.3.1
Extrinsic MOSFET capacitance
Are the extrinsic capacitances reciprocal?
6
Secs. 18.2.2,
18.5.1
Quantum capacitance
Draw band diagram for CNFET with
negative Schottky-barrier-height contacts.
How does the LDOS plot lead to the
capacitance variations?
Why the term quantum capacitance?
Label the x-axis.