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rectifier efficiency

Discussion in 'Electronic Basics' started by fredo, Nov 26, 2005.

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  1. fredo

    fredo Guest

    At higher frequencies, the rectifier seems to perform lower conversion
    efficiency.
    What is the reason?
     
  2. In over simplified terms, the junction stores charge carriers. It
    takes a while for them to fill up and provide a low resistance path
    when the junction is forward biased, and a while for them to be pulled
    out of the junction before it acts like an insulator when reverse
    biased. The higher the frequency, the bigger part of each cycle these
    transient processes take.
     
  3. fredo

    fredo Guest

    Thank you for your response.

    Just from what you mentioned, it seems that while this junction moves
    from the condition of a forward-biased to a reverse-biased, at higher
    frequency, it always causes some delay. Right? And this delay is the
    cause of the low conversion efficiency in low-frequency rectifier.
    Then, should there be a high frequency rectifier attaining some better
    efficiency in terms of conversion efficiency?

    Besides, while considering power dissipation across the diodes, at high
    frequencies, the power efficiency between IN and OUT is a great
    variation. I wonder if this is only a matter of matching.
     
  4. There are several rectifier technologies that have different
    frequency-efficiency relationships. There are PN junction diodes made
    with various semiconductor materials and with process variations
    (doping, grading, additional elements added to alter the lifetimes
    charge carrier pairs, etc) to optimize various properties and
    compromise others. There are also Schottky half junction diodes that
    involve a metal, semiconductor junction. Conduction in these
    materials does not involve positive charge carriers in the metal half
    of the junction, only electrons. This type is very fast at switching
    from conducting to insulating, but have high junction capacitance that
    passes some current in the reverse biased direction. They also have
    much lower reverse break down voltages than PN junctions made with the
    same semiconductor material. but also about half of the forward biased
    voltage drop. When made with a very high band gap semiconductor, they
    can achieve hundreds of volts reverse capability.
    Not sure what your point is. The difference between power in and
    power out should be the power dissipated by the diode.
    Finding the best technology and device type for a given application is
    a big part of the design problem. Keeping up with the technological
    advances and production availability is an ongoing task.
     
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