[20 minutes] 10.1 [15 points] A common-source amplifier is fed from a signal source having a resistance Ruig = 100 k2 and has a load resistance RL 100 kn. The MOSFET has Cgs=0.1 pF, Cgd 50 fF, gm = 1 mA/V, and ro= 100 k2. The total capacitance between the output node and ground is CL = 0.1 pF. [3 points] (a) Find the midband gain. [12 points] (b) Use the method of open-circuit time con- stants to obtain an estimate of the upper 3-dB frequency, JH. [30 minutes] 10.2 [25 points] (a) Sketch the high-frequency equivalent circuit of [5 points] a common-emitter amplifier that is fed with a volt- age signal source sig having a resistance Reig and that is loaded with a resistance RL. In addition to the internal capacitances of the BJT, C and Cμ, there is a capacitance Cz between the output node and ground. [7 points] (b) If the transistor is biased at Ic = 0.1 mA and has ẞ 100, V40 V, fr=500 MHz, and C = 0.27 pF, find the values of gm. x. Fo, and Cr [13 points] (c) Use the method of open-circuit time-constants to obtain an estimate for the upper 3-dB frequency, fH, for the case Rsig = 25 kn, RL 25 kn, and CL=0.5pF. Also, find the midband gain. [25 minutes] 10.3 [20 points] (a) An NMOS common-source amplifier with [8 points] a simple PMOS current-source load has a total capacitance at the output node of C = 10 pF. If the resistance of the signal source is very small, find the de gain, the 3-dB frequency, and the gain- bandwidth product, provided that gm = 1 mA/V and ro 20 k2 for each of the two transistors. [12 points] (b) If, in the circuit in (a), a cascode transistor is added to both the amplifier and the current-source load, find the new values of the de gain, f3dB, and the gain-bandwidth product. Assume that all tran- sistors have the same gm and ro as in (a) and that the total capacitance at the output node remains unchanged. 10.4 R Figure 10.4.1 w F R. CL For the cascode amplifier in Fig. 10.4.1 (with the dc bias circuitry not shown), gm1 = 8m2 = 2.5 mA/V, rol =F02 = 20 k2, Cgs1 = Cgs2 20 fF, Cgd1 = Cgd2 =5fF, Cdb1 = Cdb2 = 5 IF, CL=5fF, and Rsig=10 k2. Investigate two designs, one that results in a de gain of 60 dB and one that provides a de gain of 40 dB. For each case, find the required value of RL, the resulting 3-dB frequency fH, and the gain-bandwidth prod- uct. Comment on the tradeoff between gain and bandwidth. 10.5 Vaik R Figure 10.5.1 w RL HH CL [40 minutes] [30 points] [35 minutes] [30 points] 0

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