Vbe Multipliers: Temperature changes.

Discussion in 'Homework Help' started by anik321, Nov 3, 2008.

  1. anik321

    Thread Starter Member

    Oct 25, 2008
    22
    0
    Can someone help me understand what happens to the Collector voltage (BJT) of a Vbe multiplier with changes in temperature and beta?

    I believe that as Vbe changes, so will Vce (proportionately), but what is the purpose of this type of biasing if it isnt temperature stable?

    The same rational applies to changes in beta (which is affected by temperature anyway)

    am I correct in my thinking?
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A VBE voltage multiplier transistor is used to replace a few series-connected diodes to bias the output transistors in a class-AB audio power amplifier. The VBE multiplier transistor or diodes are fastened to the heatsink of the output transistors for temperature regulation. If the output transistors get hot then they draw too much current. The VBE multiplier also gets hot and reduces the current in the output transistors. If they get cold then the opposite occurs.
     
  3. anik321

    Thread Starter Member

    Oct 25, 2008
    22
    0
    How does variations in beta affect its performance/output?
     
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