Hi,
I'm new to UCD designs, and I was wondering how the oscillation/feedback network is working. If I understand it right, oscillation occurs at a 180 degree phase shift by the feedback network. So, this is why the input and output waveforms are 180 degrees out of phase?
Second, the oscillation frequency is present on the output signal. Is this hearable (probably not because switching frequencies are around 300 kHz?) or eliminated in audio?
I hope someone can clear things up a little bit 🙂
I'm new to UCD designs, and I was wondering how the oscillation/feedback network is working. If I understand it right, oscillation occurs at a 180 degree phase shift by the feedback network. So, this is why the input and output waveforms are 180 degrees out of phase?
Second, the oscillation frequency is present on the output signal. Is this hearable (probably not because switching frequencies are around 300 kHz?) or eliminated in audio?
I hope someone can clear things up a little bit 🙂
Hello,
The diff ampl. gives 180 degree phase shift, the lc filter gives another 180 degree phase shift at high frequency.
But the phase shift for the lc filter is 180 degree at infinity.
Therefore oscillation will not start, the phase lead network will push it through
the 180 degree...
You might want to read the AES paper of Bruno Putzeys : simple self oscillating class d amplifier with full output filter control.
Greetz.
The diff ampl. gives 180 degree phase shift, the lc filter gives another 180 degree phase shift at high frequency.
But the phase shift for the lc filter is 180 degree at infinity.
Therefore oscillation will not start, the phase lead network will push it through
the 180 degree...
You might want to read the AES paper of Bruno Putzeys : simple self oscillating class d amplifier with full output filter control.
Greetz.
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