Hi Guys and happy new year to all.
The last few days I have been designing current mirror circuits.
I ended up with a design that I haven’t seen before so I searched the web to see if I could find something similar, but I didn’t.
The interesting thing was that I found this patent (US 20090315618) by Sanyo published Dec. 24th 2009.
I’m really surprised that they are claiming a patent on this circuit; how small change can you actually do to a well known building block and claim a patent?
Cheers
stinius
The last few days I have been designing current mirror circuits.
I ended up with a design that I haven’t seen before so I searched the web to see if I could find something similar, but I didn’t.
The interesting thing was that I found this patent (US 20090315618) by Sanyo published Dec. 24th 2009.
I’m really surprised that they are claiming a patent on this circuit; how small change can you actually do to a well known building block and claim a patent?
Cheers
stinius
looks like mosfet feedback/buffer Q driving bjt ccm is prior art here - my post from 2005, beating their priority date by a year (not that I thought the circuit was all that original)
A somewhat symmetric mirror+vas with low base current error:
(note that gif and png are much better for line drawings than .jpg)
there are simpler approximations to an ideal diff pair but I think this works and has correct Vin scale factor
usual LtSpice source – just rename without .txt
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Hi Stinius,
This is unbelievable. They are just substituting a MOSFET for the "helper" transistor that has been in common use for decades.
Cheers,
Bob
Look at this. I worked on this over new years. Please do not build it. It´s a concept. I have seen the "helper" transistor in a book from John Linsley Hood "The Art of Linear Electronics" first published in 1993 in the reprint of 2006 by Audio Amateur on page 93 under the name "Improved Current Mirror" and it must have existed for a long time.
i claim the book : "A more sophisticated dircrete component current mirror.... where Q3 is added as a buffer to remove the base current of Q1 and Q2 from the current draw from the input....."
i claim the book : "A more sophisticated dircrete component current mirror.... where Q3 is added as a buffer to remove the base current of Q1 and Q2 from the current draw from the input....."
hi bob,
not even, as in current mirrors using mosfets, the helper is mosfet..
what they seems to patent is the use of boths bjts and mosfets in
a same current mirror..
anyway, it s easier to patent something that already exists...
regards,
Extremely annoying!
Stinius - I presume you came up with something a little more interesting.
Care to share, or are you also thinking of a patent?
So that e.g. jcx can't implement his own circuit (which precedes Sanyo's) without paying them royalties (unless he can afford to challenge the patent in court). mutter mutter mutter
Stinius - I presume you came up with something a little more interesting.
Care to share, or are you also thinking of a patent?
To the same subject there are additional this thread:
http://www.diyaudio.com/forums/pass...tent-present-prompt-christmas-eve-2009-a.html
I have contact SY to summarize these two threads
http://www.diyaudio.com/forums/pass...tent-present-prompt-christmas-eve-2009-a.html
I have contact SY to summarize these two threads
tiefbassuebertr, as i told you in your thread, the discussion about
this patent is already patented at DIY audio...in this very thread..
Member
Joined 2009
Paid Member
any patent is welcomed by the marketing department.
how true.
And a patent can be 'traded' for another patent - the tangled web of patents keeps the different manufacturers in a state of mutually assured destruction should one of them try to enforce a patent on another...
I don't understand this term
I also don't understand, what will be interesting to the fact, that I was not the person who first posted the Sanyo PDF patent here.
Fact is, two members did start independently each one thread to the same subject, and one of the members select as headline only the general term "Current mirror".
Therefore I contact SY to summarize both treads to one with the appropriate headline.
Then all members know after reading the headline, what's the actually subject and nobody must longer open two threads
Back to the topic: In the attachement an interesting approach - a combination between a current mirror and folded cascode (modified fold. Cascode, relatively new patent from National Semiconductor - perhaps the circuit topology in the new OP AMP generaion from the LME series):
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For maximum marketing leverage, don't forget to rename it. For example, the "Reed-Solomon Current Mirror".Maybe I can change the type of 'helper' transistor and re-patent the cascade Thompson mirror...
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