Kenshin
I am not sure what you are referring to specifically but the ucd-patent and the ICEpower-patent are different in the way that ICEpower uses a separate 2nd order filter before the output filter to create the phase modulation while ucd uses the existing 2nd order filter itself.
None of these patents claim a zero in the feedback loop.
I am not sure what you are referring to specifically but the ucd-patent and the ICEpower-patent are different in the way that ICEpower uses a separate 2nd order filter before the output filter to create the phase modulation while ucd uses the existing 2nd order filter itself.
None of these patents claim a zero in the feedback loop.
Hi Pabo,
It is because of what Charles said I believe:
"...Because the feedback thingie is not restricted to polyphase PWM in B&O's patent it does cover almost any PWM topology where the phase-lead is generated by a lowpass around an inner feedback loop.
It does however not cover any other topology that generates a phase-lead.
Regards
Charles
"
How many other ways can you create a phase lead? UCD uses lead compensation... you're right though I don't think it is one of their claims.
Ooooooooooohhhhhhh look.... tripath owns that patent
http://www.acutechnology.com/ClassD/pat.pdf/US05909153__.pdf
You know .... IMHO, there's far too much concern here over who's got what patented, use what works best!
It is because of what Charles said I believe:
"...Because the feedback thingie is not restricted to polyphase PWM in B&O's patent it does cover almost any PWM topology where the phase-lead is generated by a lowpass around an inner feedback loop.
It does however not cover any other topology that generates a phase-lead.
Regards
Charles
"
How many other ways can you create a phase lead? UCD uses lead compensation... you're right though I don't think it is one of their claims.
Ooooooooooohhhhhhh look.... tripath owns that patent
http://www.acutechnology.com/ClassD/pat.pdf/US05909153__.pdf
You know .... IMHO, there's far too much concern here over who's got what patented, use what works best!
I was aware of that patent but it 1.) mentions the old-fashioned method with the parallel feedback capacicor as prior art (i.e. the patent claims don't cover this) and 2.) the proposed topology is a little complicated IMO. AFAIK they don't use it for their own audio amps. I somehow remember that they wanted to use this principle for RF applications rather than audio but have to think where I got this from.
I just saw that my statement about the feedback around the inner loop was a little unprecise. No one could say anything if you use lowpass-filtered NFB around maybe an OP-AMP for making a phase-lead, even if it is the part of an inner loop of a switching amp. What is claimed is the lowpass-filtered NFB around a modulator stage.
Regards
Charles
I just saw that my statement about the feedback around the inner loop was a little unprecise. No one could say anything if you use lowpass-filtered NFB around maybe an OP-AMP for making a phase-lead, even if it is the part of an inner loop of a switching amp. What is claimed is the lowpass-filtered NFB around a modulator stage.
Regards
Charles
I found the UcD patent WO03090343 at
http://l2.espacenet.com/espacenet/a...90343&PN=WO03090343&CURDRAW=1&DB=EPD&DRDB=EP1
and the feedback do include a zero.
http://l2.espacenet.com/espacenet/bnsviewer?CY=ch&LG=en&DB=EPD&PN=WO03090343&ID=WO++03090343A2+I+
http://l2.espacenet.com/espacenet/a...90343&PN=WO03090343&CURDRAW=1&DB=EPD&DRDB=EP1
and the feedback do include a zero.
http://l2.espacenet.com/espacenet/bnsviewer?CY=ch&LG=en&DB=EPD&PN=WO03090343&ID=WO++03090343A2+I+
Pabo said:
Rf//Cf...UcD has it,Tripath has it...and SODA has it....
is it still a valid patent?
if somebody use it commercially,what would happen?
nothing? or be charged of BOTH UcD & Tripath?
is it still a valid patent?
if somebody use it commercially,what would happen?
nothing? or be charged of BOTH UcD & Tripath?
classd4sure said:
Ooooooooooohhhhhhh look.... tripath owns that patent
http://www.acutechnology.com/ClassD/pat.pdf/US05909153__.pdf
You know .... IMHO, there's far too much concern here over who's got what patented, use what works best!
phase_accurate said:
But any feedback from the filtered output implies a possibility of phase shift exceeding 180 deg and oscillate--at a frequency of 500KHz, parastical paramters such as delay of the opamp could cause unexpected oscillation easily.
A namely(topologicly) "hysteresis" or "carrier-driven" D-amp (even a namely class AB amplifier)may well be a "180 deg of phase-shift" one in fact. Boundaries between tham are clear theoreticly, ambiguous in schematic (can you tell me how SODA oscillate at a glance on its schemetic?) and almost impossible to recognize in real-world systems.
This means that "180 deg of phase-shift" modulator is rather a combine of parameters than a topology.
So it's probably that enforcing the "180 deg of phase-shift" patent really means patent the feedback from output filter and enforce it.
Now,audio amplifier industry is now at its "Bakumatsu" time.
The story,is not yet ended....
When achieveing for deep feedback & fast response,it's far easier to let the system oscillate than remain it stable. High-frequency unstable system may even have better perfomance at audio fequencies. Designing linear amplifiers is an art of tradeoff between performance and high frequency stibility.
The boom of self-oscillating D-AMP today is something like the boom of chaos(random oscillations in nonlinear systems) in 1970s~~1980s.
It's first considered something highly advanced, then turns out to be something happening everywhere but we always disliked and tried to prevent.
But at last,there will be some hard core remining. Though building a chaotic system costs only a few lines of code or a few RMBs components, it's hard to understand a chaotic system clearly even today. Optimizing a D-AMP including its nonlinear nature may be far difficult than merely build it.
The mysterious nonlinearity are now causing a dramatic revolution again -- just as it has done in math & physics.
...The new age.
The story,is not yet ended....
When achieveing for deep feedback & fast response,it's far easier to let the system oscillate than remain it stable. High-frequency unstable system may even have better perfomance at audio fequencies. Designing linear amplifiers is an art of tradeoff between performance and high frequency stibility.
The boom of self-oscillating D-AMP today is something like the boom of chaos(random oscillations in nonlinear systems) in 1970s~~1980s.
It's first considered something highly advanced, then turns out to be something happening everywhere but we always disliked and tried to prevent.
But at last,there will be some hard core remining. Though building a chaotic system costs only a few lines of code or a few RMBs components, it's hard to understand a chaotic system clearly even today. Optimizing a D-AMP including its nonlinear nature may be far difficult than merely build it.
The mysterious nonlinearity are now causing a dramatic revolution again -- just as it has done in math & physics.
...The new age.
Kenshin
I enjoy reading your posts
The ucd topology also oscillates at 180 degress lag, the zero is only there to more accurately set the switching frequency. Relying completely on parasitics for creating 180 degrees phase lag would give bad precision and large temperature dependancy. You could actually also put in a lag in order to more accurately set the frequency but it would lower the frequency which is more impractical.
I enjoy reading your posts
The ucd topology also oscillates at 180 degress lag, the zero is only there to more accurately set the switching frequency. Relying completely on parasitics for creating 180 degrees phase lag would give bad precision and large temperature dependancy. You could actually also put in a lag in order to more accurately set the frequency but it would lower the frequency which is more impractical.
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