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Subject: Re: Choosing the right transformer
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Date: Sun, 19 Jan 2003 13:49:41 -0500
NNTP-Posting-Date: Sun, 19 Jan 2003 13:49:43 EST
sorry for the double posting... was having trouble with my outlook
"JAke" wrote in message
> I am not quite sure i get the whole feedback idea... Why would we try to
> close the loop around the modulator? That does not make any sense to me.
> The actual "amplifier" is the class D analog circuit (the H bridge), if
> there are any feedback to be put in this design, shouldn't it be between
> output of the H bridge and the input of the H bridge, NOT the input of the
> modulator. Or am i just missing something?
> "Greg" wrote in message
> > Here's the block diagram of the system
> > CD player -->digital out-->(DSP or FPGA)-->one-bit
> > output-->Hbridge--->Filter--->Speaker
> > I really don't see how you could feed back the output of the Hbridge in
> > DSP to correct the power supply irregularities.
> > "Chuck Simmons" wrote in message
> > news:3E2AEA6B.1A9BBDD1@webaccess.net...
> > > Greg wrote:
> > > >
> > > > > Ripple voltage on the supply will only be modulated onto the
> > > > > you design the amplifier with no negative feedback. You aren't
> > to
> > > > make
> > > > > an "open loop" class D amp, are you?
> > > >
> > > > What does everyone has against ''open loop'' class D amp. TI does it
> > I
> > > > don't see how closing the loop could be done if the modulator is
> > implemented
> > > > in DSP.
> > > > Any ideas?
> > >
> > > As pointed out, power supply regulation becomes a problem.
> > >
> > > Why cannot the loop be closed in a DSP? Most DSP applications I know
> > > are closed loop and some involve PWM. Can you explain what you mean?
> > >
> > > Chuck
> > > --
> > > ... The times have been,
> > > That, when the brains were out,
> > > the man would die. ... Macbeth
> > > Chuck Simmons firstname.lastname@example.org
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