Anybody solve this mosfet transconductance problem

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In summary, the conversation is discussing a mosfet transconductance problem and the use of cascode configuration in amplifier stages. The answer to the problem is option (C) and the purpose of the second transistor is to improve high frequency performance by breaking capacitive feedback.
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munna007
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anybody please solve this mosfet transconductance problem ...

hello friends...i can't understand about this question totally...can anybody help me regarding this...its answer is option (C).

.i have attached image for this question ,question no. 48...

thanks...
 

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The definition of "saturation mode" in a mosfet is that Id is independent of Vds and only dependant on (Vgs-VT). It follows that as long as the bias voltage at the gate of M2 is such that M1 remains in the saturation region then Id1 (and hence Id2) will only depend upon Vgs1. In other words, the characteristics from Vg1 to Id2 of the pair is essentually the same as that of M1 alone.

BTW. This is known as "Cascode" configuration and an amplifier stage constructed from such a pair actually corresponds to a common source - common gate multistage (common emitter - common base pair in the case of BJT's replacing the mosfets).

Since the gain of this pair is equal to that of just the CS stage (or CE in the BJT case) alone then you may wonder what is the purpose of introducing the second transistor. It turns out that the difference is at high frequency operation. Here the (AC) grounded gate of M2 breaks the capacitive feedback from output to input which can drastically improve the high frequency performance.
 
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What is a MOSFET?

A MOSFET (metal-oxide-semiconductor field-effect transistor) is a type of transistor that is commonly used in electronic devices as a switch or amplifier.

What is transconductance?

Transconductance is a measure of the efficiency of a transistor to amplify a signal. It is the ratio of change in output current to the change in input voltage.

What is a MOSFET transconductance problem?

A MOSFET transconductance problem refers to a question or issue related to the calculation or analysis of the transconductance of a MOSFET transistor.

How do you solve a MOSFET transconductance problem?

Solving a MOSFET transconductance problem involves understanding the basic principles of MOSFET transistors and using equations and calculations to determine the transconductance value.

Why is understanding MOSFET transconductance important?

Understanding MOSFET transconductance is important for designing and analyzing electronic circuits and devices that use MOSFET transistors. It allows for efficient and accurate performance of the transistor, which affects the overall functioning of the electronic device.

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