Hello Tech Netters:

    I had an Engineer ask me the following, and I do not have any idea
    if this has been done or simulated before.  If anyone has any input,
    real or theory.....


     He asks: 
     
        I am looking for information on pc/flex layouts where twisted pair 
     cables have been simulated in the artwork.  The purpose of the twisted 
     pair is to reduce the radiated magnetic field.  I am considering using 
     this approach for audio signals (150 Hz to 7.5 KHz).  Below is a very 
     crude representation of the layout.
     
     
        *       x       *       x       *       x
          *   x   x   *   *   x    x  *   *   x
            *       *       *       *       * 
          x   *   *   x   x   *   *    x   x  *
        x       *       x       *        x      *
     
        
        The * represents 1 trace (top layer) and the x represents the 
     2nd trace ( bottom layer).  This concept needs to fit on a double 
     sided flex.  Ideally the representation above needs to have the 90 
     degree corners replaced with curved lines.  The pattern should be 
     symetrical on both layers. 

        An alternative rigid application could be
     
        *       o       o       o       o       x 
          *   x   *   x   *   x    *  x   *   x
            x       x       x       x       x 
          x   *   x   *   x   *   x    *   x  *
        x       o       o       o        o      *
     
        Where the o represents a via and the traces "twist" about each other.

     
        Any info you can get on layout considerations and performance would 
     be appreciated.
     

                                   '''
                                  (O O)
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