Transcript
COLORADO STATE UNIVERSITY ECE 332: ELECTRONIC PRINCIPLES II HOMEWORK 3 1. The figure below shows a scheme for coupling and amplifying a high-frequency pulse signal. The circuit utilizes two MOSFETs whose bias details are not shown and a 50Ξ© coaxial cable. Transistor π1 operates as a CS amplifier and π2 as a CG amplifier. For proper operation, transistor π2 is required to present a 50Ξ© resistance to the cable. This situation is known as βproper terminationβ of the cable and ensures that there will be no signal reflection coming back on the cable. When the cable is properly terminated, its input resistance is 50Ξ©. What must ππ2 be? If π1 is sized and biased the same as π2 (i.e. they have the same gm), What is the amplitude of the current pulses in the drain of π1 ? (5mV shown in the diagram is its AC input signal. The DC bias to make it in saturation is not shown.) What is the amplitude of the voltage pulses in the drain of π1 ? What value of π
π· is required to provide 1V pulses at the drain of π2 ?
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2. Use the figures shown below for this problem. a) The NMOS transistor in the source-follower circuit of figure (a) has ππ = 5 ππ΄/π and a large π
π . (assuming it is infinite, rather than 10KOhm shown in the diagram). Find the open-circuit voltage gain and the output resistance. b) The NMOS transistor in the common-gate amplifier of figure (b) has ππ = 5 ππ΄/π and a large π
π . (assuming it is infinite, rather than 10KOhm shown in the diagram). Find the input resistance and the voltage gain. c) If the output of the source follower in (a) is connected to the input of the common-gate amplifier in (b), use the results of (a) and (b) to obtain the overall voltage gain π£π /π£π . (Still assume π
π in both circuits are infinite, rather than 10KOhm shown in the diagram)
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