Class D Audio Amplifier - Control system

Discussion in 'The Projects Forum' started by Skeebopstop, Jan 5, 2010.

  1. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    358
    3
    Hello all,

    I've finished my project of designing a Class D audio amp using the IRS2092 and boy is that chip ever great, blows your clothes off and sounds great.

    That aside, now I am going back to try and really understand the inner workings of this beauty so I have posted a diagram of the control system to which I am banging my head.

    1. Why use a transconductance amplifier instead of standard op amp considering it just feeds into a comparator?
    2. I believe the app note claims that it runs a 2nd order integrator with the configuration shown, but I can't get my head around transconductance integration, nor how that T bridge capacitor network makes it 2nd order? Any help?

    Thanks in advance,

    James
     
  2. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    358
    3
    Just had a thought. Since the control loop directly feeds back the high voltage PWM signal into the self oscillating circuit shown, it would make sense to go transconductance so the output of the integrator is not susceptible to these large and high frequency voltage signals as the feedback current is very small?
     
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