Ideal Class-D PA question

Discussion in 'General Electronics Chat' started by maam_13, Apr 9, 2013.

  1. maam_13

    Thread Starter New Member

    Mar 23, 2008
    7
    0
    Hi all,

    I am designing this CMCD-PA using Agilent ADS. I would like to know, why did the voltage at output load (R4) form a half sinusoidal shape?
    Shouldn't it be a full sinusoidal waveform, similar to the current at R4??

    You can refer to my schematic and the output in the attachment below.

    TQ
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    That sinewave appears to be ringing in the circuit with a frequency of about 1GHz.

    What are you using such a fast switching frequency (1GHz!). That's several orders of magnitude higher than could be done in a practical amplifier.
     
  3. maam_13

    Thread Starter New Member

    Mar 23, 2008
    7
    0
    For realization I'm using fast switching transistor such as GaN-HEMT which support up to 2GHz.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    But what's the reason for using such a high frequency? It just creates a lot of switching losses. I don't see any reason for that in a Class-D power amp. :confused:
     
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