diode balanced mixer

Discussion in 'Homework Help' started by anhnha, May 11, 2012.

  1. anhnha

    Thread Starter Active Member

    Apr 19, 2012
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    45
    Could you help me explain why the voltage drop in 2 diodes have phase reverse?
    And could you give me more detail about how this circuit work?
    I had try to google but I still get stuck.
    Thanks in advance.
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,977
    3,221
    Since the local oscillator is connected to the center taps of the two transformers it applies an equal (the same) voltage to both diodes. When this voltage is positive on the anode of the diodes, both diodes can conduct to the output transformer in response to the input voltage. When this voltage is negative on the diodes, both diodes are reverse-biased and do not conduct any of the input voltage to the output transformer.
     
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  3. anhnha

    Thread Starter Active Member

    Apr 19, 2012
    773
    45
    Thanks for your help.
    I got it but I don't understand this from my texbook:
    UthD1 = Uth cos(ωth.t)
    UthD2 = Uth cos(ωth.t + π )
    UnsD1 = UnsD2 = Uns
    i tg1 = I tg1 cos(ωns – ωth)t
    i tg1 = -I tg2 cos[(ωns – ωth)t + π ] = -I tg2 cos(ωns – ωth)t
    Could you help me why UthD1 and UthD2 have phase reverse?
     
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