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Mos5 I'd Length Modulation

The lecture discusses the Drain Current ID with channel length modulation, highlighting the ID-VDS characteristics and the concept of Early Voltage (VA) as a process-technology parameter. It also explains the Body Effect, where the body terminal's voltage influences the drain current ID, effectively acting as an additional gate for MOSFETs. The lecture concludes with a quiz link for students.

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11 views9 pages

Mos5 I'd Length Modulation

The lecture discusses the Drain Current ID with channel length modulation, highlighting the ID-VDS characteristics and the concept of Early Voltage (VA) as a process-technology parameter. It also explains the Body Effect, where the body terminal's voltage influences the drain current ID, effectively acting as an additional gate for MOSFETs. The lecture concludes with a quiz link for students.

Uploaded by

adwaitdubey14
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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EI-27003: Electronics Devices and Circuits

Lecture - 11

Subject Incharge: Mr. Rajesh Khatri


Associate Professor

LECTURE - 11

Year: 2020-21
Drain Current ID with channel length Modulation

Drain Current ID with channel length Modulation

ID –VDS characteristics with Channel length modulation
effect
• Fig shows ID-VDS characteristics with channel length modulation effect.
• From this fig we can observe that when straight line I D-VDS characteristics
are extrapolated they intercept the VDS-axis at point VDS= -VA.
Early Voltage
• From eq.(6): ID=0 at VDS= -1/ λ
• It follows that VA= 1/ λ.
• Thus VA is a process-technology parameter with dimensions of
V.
• VA is proportional to channel length L
VA ᶑ L or VA = VA’L
 VA’ is another process-technology parameter with dimensions
of V/µm.

 But the Voltage VA is usually referred to as the Early voltage (J.


M. Early)
Body Effect (Role of Body Terminal)
 We know that the Body(Substrate) of NMOS is connected to GND(most –ve
terminal) and that of PMOS is connected to VDD (most +ve terminal).
 This is done to make diode formed between induced channel and body,
reverse bias. i.e. body becomes inactive.

 Now if some +ve or –ve voltage is applied between source and body(VSB),
then it will have some effect on device operation.
 Let us consider NMOS and let its substrate is made –ve relative to source.
Body Effect

Body Effect
 Equation (A) indicates that an incremental change in VSB gives rise to an
incremental change in Vt which in turn results in an incremental change in
ID even though VGS might have been kept constant

 It follows that the body voltage controls drain current ID, thus body acts as
another gate for MOSFET, a phenomenon known as Body Effect.

 Body/substrate is sometimes also called as Back Gate of MOSFET.


Its time for Quiz

https://forms.gle/UB7fsWHeq1zNUNMM9

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