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Consider the amplifier of Fig. 7.2(a) with VDD = 1.8 V, RD = 17.5 k, and with a MOSFET
Chapter 7, Problem 7.1(choose chapter or problem)
Consider the amplifier of Fig. 7.2(a) with \(V_{D D}=1.8\) V, \(R_D=17.5\mathrm{\ k}\Omega\), and with a MOSFET specified to have \(V_{t}=0.4\) V, \(k_{n}=4 \mathrm{~mA} / \mathrm{V}^{2}\), and \(\lambda=0\). Determine the coordinates of the end points of the active-region segment of the VTC. Also, determine \(\left.V_{D S}\right|_{C}\) assuming \(\left.V_{G S}\right|_{C}=V_{D D}\).
Questions & Answers
QUESTION:
Consider the amplifier of Fig. 7.2(a) with \(V_{D D}=1.8\) V, \(R_D=17.5\mathrm{\ k}\Omega\), and with a MOSFET specified to have \(V_{t}=0.4\) V, \(k_{n}=4 \mathrm{~mA} / \mathrm{V}^{2}\), and \(\lambda=0\). Determine the coordinates of the end points of the active-region segment of the VTC. Also, determine \(\left.V_{D S}\right|_{C}\) assuming \(\left.V_{G S}\right|_{C}=V_{D D}\).
ANSWER:
Step 1 of 5
Consider the figure 7.2(a) for the amplifier circuit.
In figure 7.2(b), the end points of the active region segment of the voltage transfer characteristics are point A and point B.
Point A is the point at which the transistor is changed from cutoff region to saturation region.
For \(v_{DS}<V_{t}\), the MOSFET will be in the cutoff region.
For \(v_{DS}\geq V_{t}\) the MOSFET enter in to saturation region and hence \(v_{GS}=V_{t}\) is the x-co-ordinate at point A.
Gate source voltage of point A is \(V_{t}\)
The threshold voltage of MOSFET is \(V_{t}=0.4V\)
Therefore,the gate source voltage at point A is \(0.4\ V\).