ELECTRONICS-I
Field Effect Transistors (FET)
Metal Oxide Semiconductor Field Effect Transistor (MOSFET)
• Yrd. Doç. Dr. Nihan Kosku Perkgöz
Field Effect Transistor -FET
• FETs are majority-charge-carrier -UNIPOLAR
devices (only electrons or holes carry current).
• Much smaller than BJTs.
• Most of the manufactured transistors are FETs.
• High input resistance to the signal source,
drawing little input power,
• Low resistance to the output circuit, so it
supplies a large current to drive the circuit load.
http://www.electronics-tutorials.ws/transistor/tran_6.html
The gate turns the transistor (inversion layer) on and off with an electric field through the oxide.
Field Effect Transistor -FET
• Different types:
–
–
–
–
–
–
MOSFET (Metal–Oxide–Semiconductor Field-Effect Transistor),
JFET (Junction field-effect transistor),
MESFET (Metal–Semiconductor Field-Effect Transistor),
MODFET (Modulation-Doped Field Effect Transistor),
HEMT (High electron mobility transistor)
…
MESFET
MOSFET
JFET (Junction field-effect transistor)
Richard C. Jaeger Travis N. Blalock Jaeger «Microelectronic Circuit Design»
CMOS –complementary MOS
• -The CMOS (complementary metal oxide semiconductor) process technology
is the basis for modern digital integrated circuits. This process technology uses
an arrangement where the ("enhancement-mode") p-channel MOSFET and nchannel MOSFET are connected in series such that when one is on, the other
is off.
p-channel MOSFET
n-channel MOSFET
n-channel enhancement-mode MOSFET
http://www.utdallas.edu/~torlak/courses/ee3311/lectures/
Metal-Oxide-Semiconductor (MOS) Capacitor
http://www.utdallas.edu/~torlak/courses/ee3311/lectures/
Formation of Channel
http://www.utdallas.edu/~torlak/courses/ee3311/lectures/
Characteristics of MOSFETs
Donald A. Neaman «Electronic Circuit Analysis and Design»
Characteristics of MOSFET
For small values of VDS:
When VGS< VTH, the drain current
is zero.
When VGS> VTH, inversion charge
layer is formed and the drain
current increases with VDS.
For VDS > VGS-VTH :
When VGS< VTH, the drain current
is zero.
http://www.utdallas.edu/~torlak/courses/ee3311/lectures/
When VGS> VTH, the drain current
increases with VDS until saturation
point
(until
the
potential
difference across the oxide at the
drain terminal is equal to VTH).
Channel Pinch-off
Richard C. Jaeger Travis N. Blalock Jaeger «Microelectronic Circuit Design»
n-channel & p-channel
D
G
D
G
S
S
I-V Characteristics
Operation in the Triode (Linear) Region
Operation in the Saturation Region
Richard C. Jaeger Travis N. Blalock Jaeger «Microelectronic Circuit Design»