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is defined as the minimum voltage required between gate and source to turn the transistor on (allow it to conduct electricity). Due to this definition, overdrive voltage is also known as "excess gate voltage" or "effective voltage." Overdrive voltage can be found using the simple equation:
152:, the drain voltage relative to the source, which can be used to determine the region of operation of the MOSFET. The table below shows how to use overdrive voltage to understand what region of operation the MOSFET is in:
259:> 0) will attract electrons and repel holes, and this is called depletion because we are depleting the number of holes. At a critical voltage called the threshold voltage (V
263:) the channel will actually be so depleted of holes and rich in electrons that it will INVERT to being n-type silicon, and this is called the inversion region.
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In an NMOS transistor, the channel region under zero bias has an abundance of holes (i.e., it is p-type silicon). By applying a negative gate bias (V
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255:< 0) we attract more holes, and this is called accumulation. A positive gate voltage (V
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Sedra and Smith, Microelectronic
Circuits, Fifth Edition, (2004) Chapter 4,
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The MOSFET is delivering current in a linear relationship to the voltage (V
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is important as it directly affects the output drain terminal current (I
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The MOSFET is turned off, and should not be delivering any current.
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Overdrive voltage is also important because of its relationship to V
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provides insufficient context for those unfamiliar with the subject
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The MOSFET is delivering a high amount of current, and changing V
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81:, is typically referred to in the context of
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248:A more physics-related explanation follows:
59:Learn how and when to remove this message
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358:Lecture Note of Prof Liu, UC Berkeley
41:providing more context for the reader
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266:As we increase this voltage, V
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141:can be increased until
375:Electrical parameters
319:Short-channel effect
314:Electronic amplifier
161:Region of Operation
92:) in excess of the
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347:978-0-19-533883-6
309:Threshold voltage
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187:Saturation (CCR)
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72:Overdrive voltage
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164:Description
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49:October 2009
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35:Please help
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158:Conditions
86:transistors
369:Categories
330:References
270:, beyond V
143:saturation
121:Technology
100:) where V
298:See also
385:MOSFETs
324:Biasing
239:Cutoff
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304:MOSFET
282:, or V
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