265AMidterm_Fall_2003 - Noise Figure (in dB)? Verify the...

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ECE 265A MIDTERM EXAM - II This is a take-home exam. You are not allowed to work with any of your friends or colleagues on the exam. It is due at 5PM on Nov. 25, 2003. Points will be taken off for messy, sloppy, or unsupported answers. 1) (50 pts) A 2GHz common-emitter bipolar transistor LNA has the following simplified transistor characteristics. β =100, rb=20 , Cbe=0, Cbc=0, I c = 2 mA. Derive the general expression for the optimum source impedance to minimize the Noise Figure of the amplifier, including intermediate derivations of the equivalent input noise voltage, noise current and correlation admittance. What is the minimum
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Unformatted text preview: Noise Figure (in dB)? Verify the minimum Noise Figure at the calculated admittance using ADS. 2) (50 pts) Now, place an ideal transformer between the 50 ohm source and the base of the common-emitter transistor, whose turns ratio provides the optimum admittance so the Noise Figure is minimized. Calculate the resulting IIP3 of the amplifier and verify your results with ADS. Plot the calculated IIP3 and NF as a function of source admittance for this amplifier. Describe the tradeoff between linearity and noise....
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This note was uploaded on 04/02/2011 for the course ECE 264 taught by Professor Song during the Spring '11 term at UCSB.

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