Two identical NMOS transistors M1 and M2 are connected as shown below. The circuit is used as an amplifier with the input connected between G and S terminals and the output taken between D and S terminals. Vbias and VD are so adjusted that both transistors are in saturation. The transconductance of this combination is defined as g_{m} = \;{∂i_{D}}/{∂V_{GS}_{\:}} while the output resistance is r_{o} = \;{∂V_{GS}_{\:}}/{∂i_{D}}\:, where iD is the current flowing into the drain of M2. Let gm1, gm2 be the transconductances and r01, r02 be the output resistances of transistors M1 and M2, respectively.Which of the following statements about estimates for gm and r0 is correct?

Question

Two identical NMOS transistors M1 and M2 are connected as shown below. The circuit is used as an amplifier with the input connected between G and S terminals and the output taken between D and S terminals. Vbias and VD are so adjusted that both transistors are in saturation. The transconductance of this combination is defined as g_{m} = \;{∂i_{D}}/{∂V_{GS}_{\:}} while the output resistance is r_{o} = \;{∂V_{GS}_{\:}}/{∂i_{D}}\:, where iD is the current flowing into the drain of M2. Let gm1, gm2 be the transconductances and r01, r02 be the output resistances of transistors M1 and M2, respectively.Which of the following statements about estimates for gm and r0 is correct?

Examsnet · Accepted Answer

Correct Answer is : 𝑔𝑚 ≈ 𝑔𝑚1  and  𝑟0 ≈ 𝑟01. 𝑔𝑚2. 𝑟02

GATE Electronics and Communications (EC) 2018 Solved Paper