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Help with electronics question. Urgent!

Discussion in 'Electronics Homework Help' started by sarah90, Aug 23, 2011.

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  1. sarah90

    sarah90

    1
    0
    Aug 23, 2011
    Hi there Im a student, studying at college and I have an exam coming up and need help with this mock paper, but I have no idea because It is very hard for me, if you could do the calculations for me I could learn the methods and understand. thank you for you help. regards Sarah. I have attached the file on the website with the link below.

    http://www.megaupload.com/?d=QVTGKRME
     
  2. daddles

    daddles

    443
    3
    Jun 10, 2011
    Like you've been told elsewhere, show what you've done so far and someone might critique your work. Don't expect people to do your work for you. Besides, your question is exactly what you should have asked your instructor if you didn't understand the stuff in class.
     
  3. Laplace

    Laplace

    1,252
    184
    Apr 4, 2010
    1.(a) - Does the {gain x bandwidth} constant have any relevance here?

    1.(a)(i) - Does a 20kΩ resistor to ground have the same impedance as a 20kΩ resistor to virtual ground?

    1.(a)(ii) - Google 'differential amplifier'
    http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opampvar7.html#c1

    1.(a)(iii) - Try using a current sensing resistor with the voltage across the resistor amplified by a difference amplifier. Select the value of the resistor and the gain of the amplifier so that 100 mA through the resistor causes 1 V output from the amplifier.

    1.(b) - Google 'summing amplifier'
    http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opampvar5.html#c1
    How would a weighted sum relate to digital binary DAC inputs?

    2.(a) - Google 'flash ADC'
    http://www.maxim-ic.com/app-notes/index.mvp/id/810
    No need to design the logic circuit; an input/output logic table should be more than sufficient.

    2.(b) - Here is a good answer for you:

    http://uk.answers.yahoo.com/questio...D8s2b6kqT31G;_ylv=3?qid=20110823120155AAB7So0

    3.(a)(i),(ii) - Zi is an RC network feeding a virtual ground, so the current through the input resistor and capacitor is the same current through Zf. Therefore Vo is directly proportional to the current through the RC network. How does an RC network respond to a square wave?

    3.(a)(iii) - The {gain x bandwidth} of the filter is set by the passive components and the input frequency range. What happens when this exceeds the {gain x bandwidth} of the active component?

    3.(a)(iv) - What does 3.(a)(i) suggest?

    3.(b) - Mercifully you have the equations, and Ri & Rf for the loop gain.
     
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