I\'ve never seen that in my On 2020-08-25 12:14, jlarkin@highlandsniptechnology.com wrote:
On Tue, 25 Aug 2020 20:11:40 +0530, Pimpom <nobody@nowhere.com> wrote:
On 8/25/2020 6:56 PM, legg wrote:
On Mon, 24 Aug 2020 14:41:12 -0700, John Robertson <spam@flippers.com
wrote:
Or you just reinvented them after forgetting you had glanced at the ap
notes sheets all those many years ago, like we all do...
I had a boss like that once, only it took him as little as 7 days
to forget that some ideas weren\'t actually his own.
RL
The only boss I ever had was just the opposite. I won an argument
with him over a technical design point. He was a Ph.D. in
biomedical electronics. I was 19 and had taught myself
electronics over the past 1.5 years. When the internet came to my
region 28 years later, I found his email address and contacted
him. One of the first things he said in his reply was to mention
that project and went on to say \"You taught me a good lesson that
day......\"
In science, there is always one correct theory, so scientists are
motivated to find it and scorn others. They tend to brutally mock a
colleague who may be in error; I\'ve seen it happen in person several
times.
You need to run with a better crowd.
life--UBC, Microtel, Stanford, and IBM Research were all pretty
collegial. (Some of the IBM product divisions were a bit less so--there
were folks there who seemed to think their job was to throw rocks at
everybody else\'s ideas, but they weren\'t scientists.)
On Wed, 26 Aug 2020 08:54:47 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-25 12:14, jlarkin@highlandsniptechnology.com wrote:
On Tue, 25 Aug 2020 20:11:40 +0530, Pimpom <nobody@nowhere.com> wrote:
On 8/25/2020 6:56 PM, legg wrote:
On Mon, 24 Aug 2020 14:41:12 -0700, John Robertson <spam@flippers.com
wrote:
Or you just reinvented them after forgetting you had glanced at the ap
notes sheets all those many years ago, like we all do...
I had a boss like that once, only it took him as little as 7 days
to forget that some ideas weren\'t actually his own.
RL
The only boss I ever had was just the opposite. I won an argument
with him over a technical design point. He was a Ph.D. in
biomedical electronics. I was 19 and had taught myself
electronics over the past 1.5 years. When the internet came to my
region 28 years later, I found his email address and contacted
him. One of the first things he said in his reply was to mention
that project and went on to say \"You taught me a good lesson that
day......\"
In science, there is always one correct theory, so scientists are
motivated to find it and scorn others. They tend to brutally mock a
colleague who may be in error; I\'ve seen it happen in person several
times.
You need to run with a better crowd.
life--UBC, Microtel, Stanford, and IBM Research were all pretty
collegial. (Some of the IBM product divisions were a bit less so--there
were folks there who seemed to think their job was to throw rocks at
everybody else\'s ideas, but they weren\'t scientists.)
I\'ve seen some shocking rudeness among physicists. One poor undergrad
was making an oral presentation, to get into grad school, when the
dean said \"I\'ve heard enough\" and walked out. The guy was crushed. And
I was at a meeting, about a project at CERN, when my physicist friend
made a small mistake and was publicly savaged by a rival. Both events
impressed me. I\'ve seen a few milder cases too.
On 2020-08-26 11:21, jlarkin@highlandsniptechnology.com wrote:
On Wed, 26 Aug 2020 08:54:47 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-25 12:14, jlarkin@highlandsniptechnology.com wrote:
On Tue, 25 Aug 2020 20:11:40 +0530, Pimpom <nobody@nowhere.com> wrote:
On 8/25/2020 6:56 PM, legg wrote:
On Mon, 24 Aug 2020 14:41:12 -0700, John Robertson <spam@flippers.com
wrote:
Or you just reinvented them after forgetting you had glanced at the ap
notes sheets all those many years ago, like we all do...
I had a boss like that once, only it took him as little as 7 days
to forget that some ideas weren\'t actually his own.
RL
The only boss I ever had was just the opposite. I won an argument
with him over a technical design point. He was a Ph.D. in
biomedical electronics. I was 19 and had taught myself
electronics over the past 1.5 years. When the internet came to my
region 28 years later, I found his email address and contacted
him. One of the first things he said in his reply was to mention
that project and went on to say \"You taught me a good lesson that
day......\"
In science, there is always one correct theory, so scientists are
motivated to find it and scorn others. They tend to brutally mock a
colleague who may be in error; I\'ve seen it happen in person several
times.
You need to run with a better crowd.
life--UBC, Microtel, Stanford, and IBM Research were all pretty
collegial. (Some of the IBM product divisions were a bit less so--there
were folks there who seemed to think their job was to throw rocks at
everybody else\'s ideas, but they weren\'t scientists.)
I\'ve seen some shocking rudeness among physicists. One poor undergrad
was making an oral presentation, to get into grad school, when the
dean said \"I\'ve heard enough\" and walked out. The guy was crushed. And
I was at a meeting, about a project at CERN, when my physicist friend
made a small mistake and was publicly savaged by a rival. Both events
impressed me. I\'ve seen a few milder cases too.
When I was taking Ron Bracewell\'s graduate Fourier Transforms class
(back around 1984ish), the subject of the politics of tenure came up.
He said,
\"If you\'re in a place where tenure committees knife people, you\'re much
better off getting knifed.\"
Cheers
Phil Hobbs
9eakftpajnd1lncmi09km6789riupttuq@4ax.com...Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
... as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever another to
find an existing idea to copy and rework it for a new purpose until now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
... as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever another to
find an existing idea to copy and rework it for a new purpose until now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
The best ideas are usually not patentable...for example... my latest asics
have an oscillator topology resulting in at least 10 dB better close in
phase noise, yet the topology is too conventional to be patent worthy, even
though it don\'t seem to have been used for this purpose before.
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to patent,
but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever another
to
find an existing idea to copy and rework it for a new purpose until now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
Since it\'s patented, please tell us how it works!
\"John Larkin\"Â wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...
On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is
done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
Since it\'s patented, please tell us how it works!
So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...
The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.
A diff pair can only take about 50mV max whatever the gain control tail
current does.
Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.
Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.
Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.
The 1st application actually got rejected, not surprisingly, the idea of
using S curves to compensate processes had already been
patented...However very surprisingly, our man reworked it to make it
more specific and bobs your uncle....
For me, what is significant is that.....
Usually, top brass pass down the chain decide what they want to produce,
and the surfs churn the handle for them.
In this case, I was pondering the problem of poor yields due to the
variability of the xtals and the knowledge of Gilberts technique popped
up in my noggin as a solution. I explained the idea to my local work
mates, we did some simulations with real xtal data and tanh() in Excel
and convinced ourselves that it would work. We presented the idea to top
brass and they said go ahead, make a test ASIC. Although a few teething
issues with the ASIC, it worked well enough to prove the concept worked.
So, this is a method that should give at least a 5 times improvment in
temperature stability, yet originated from a surf with no remit....
On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...
On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is
done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
Since it\'s patented, please tell us how it works!
So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...
The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.
A diff pair can only take about 50mV max whatever the gain control tail
current does.
Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.
Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.
Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.
The 1st application actually got rejected, not surprisingly, the idea of
using S curves to compensate processes had already been
patented...However very surprisingly, our man reworked it to make it
more specific and bobs your uncle....
For me, what is significant is that.....
Usually, top brass pass down the chain decide what they want to produce,
and the surfs churn the handle for them.
In this case, I was pondering the problem of poor yields due to the
variability of the xtals and the knowledge of Gilberts technique popped
up in my noggin as a solution. I explained the idea to my local work
mates, we did some simulations with real xtal data and tanh() in Excel
and convinced ourselves that it would work. We presented the idea to top
brass and they said go ahead, make a test ASIC. Although a few teething
issues with the ASIC, it worked well enough to prove the concept worked.
So, this is a method that should give at least a 5 times improvment in
temperature stability, yet originated from a surf with no remit....
Well, get out the serfboard and celebrate.
That\'s a cute technique, thanks. My underwater projects are always the
best too.
Cheers
Phil Hobbs
tirsdag den 25. august 2020 kl. 09.38.40 UTC+2 skrev Bill Sloman:
On Tuesday, August 25, 2020 at 2:44:02 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Mon, 24 Aug 2020 14:41:12 -0700, John Robertson <sp...@flippers.com
wrote:
On 2020/08/24 12:34 p.m., John Larkin wrote:
On Mon, 24 Aug 2020 12:19:13 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Sunday, August 23, 2020 at 5:18:44 PM UTC-4, jla...@highlandsniptechnology.com wrote:
I think this works:
https://www.dropbox.com/s/sry0g1t9jmx6wvb/Depl_Follower.jpg?raw=1
--
John Larkin Highland Technology, Inc
Science teaches us to doubt.
Claude Bernard
Seriously. Siliconix and International Rectifier published those topologies 30 years ago.
Then it just shows how clever I am to re-invent them.
Or you just reinvented them after forgetting you had glanced at the ap
notes sheets all those many years ago, like we all do...
No. I invent circuits.
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on Baxandall\'s class-D oscillator (which nobody has bothered to patent, but I\'ve not seen anywhere either).
if it takes so long to make that the patent is expired before it is done why bother
On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\"Â wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...
On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is
done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
Since it\'s patented, please tell us how it works!
So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...
The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.
A diff pair can only take about 50mV max whatever the gain control tail
current does.
Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.
Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.
Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.
The 1st application actually got rejected, not surprisingly, the idea of
using S curves to compensate processes had already been
patented...However very surprisingly, our man reworked it to make it
more specific and bobs your uncle....
For me, what is significant is that.....
Usually, top brass pass down the chain decide what they want to produce,
and the surfs churn the handle for them.
In this case, I was pondering the problem of poor yields due to the
variability of the xtals and the knowledge of Gilberts technique popped
up in my noggin as a solution. I explained the idea to my local work
mates, we did some simulations with real xtal data and tanh() in Excel
and convinced ourselves that it would work. We presented the idea to top
brass and they said go ahead, make a test ASIC. Although a few teething
issues with the ASIC, it worked well enough to prove the concept worked.
So, this is a method that should give at least a 5 times improvment in
temperature stability, yet originated from a surf with no remit....
Well, get out the serfboard and celebrate.
That\'s a cute technique, thanks. My underwater projects are always the
best too.
Given that you can approximate a function out of N piecewise segments
of arbitrary length and slope, is there a process to locate the
segment endpoints for minimum (peak or RMS maybe) error? I usually do
it by eyeball but there must be a better way.
Overlapped TANHs is cute. One could slide them around (offset) and
adjust their slopes (tail currents).
torsdag den 27. august 2020 kl. 20.40.25 UTC+2 skrev Kevin Aylward:
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
... as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever another to
find an existing idea to copy and rework it for a new purpose until now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
The best ideas are usually not patentable...for example... my latest asics
have an oscillator topology resulting in at least 10 dB better close in
phase noise, yet the topology is too conventional to be patent worthy, even
though it don\'t seem to have been used for this purpose before.
is it not enough that it hasn\'t been used for the purpose before?
plenty of patents with old ideas and \"on the internet\" tagged on
On 28/8/20 5:21 am, Lasse Langwadt Christensen wrote:
torsdag den 27. august 2020 kl. 20.40.25 UTC+2 skrev Kevin Aylward:
wrote in message news
On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...
On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is
done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
Since it\'s patented, please tell us how it works!
So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...
The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.
A diff pair can only take about 50mV max whatever the gain control tail
current does.
Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.
Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.
Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.
The 1st application actually got rejected, not surprisingly, the idea of
using S curves to compensate processes had already been
patented...However very surprisingly, our man reworked it to make it
more specific and bobs your uncle....
For me, what is significant is that.....
Usually, top brass pass down the chain decide what they want to produce,
and the surfs churn the handle for them.
In this case, I was pondering the problem of poor yields due to the
variability of the xtals and the knowledge of Gilberts technique popped
up in my noggin as a solution. I explained the idea to my local work
mates, we did some simulations with real xtal data and tanh() in Excel
and convinced ourselves that it would work. We presented the idea to top
brass and they said go ahead, make a test ASIC. Although a few teething
issues with the ASIC, it worked well enough to prove the concept worked.
So, this is a method that should give at least a 5 times improvment in
temperature stability, yet originated from a surf with no remit....
Well, get out the serfboard and celebrate.
That\'s a cute technique, thanks. My underwater projects are always the
best too.
Cheers
Phil Hobbs
Given that you can approximate a function out of N piecewise segments
of arbitrary length and slope, is there a process to locate the
segment endpoints for minimum (peak or RMS maybe) error? I usually do
it by eyeball but there must be a better way.
\"John Larkin\" wrote in message
news:5b5gkf5m98m00prljl4ihrgee7mc7d8jh9@4ax.com...
On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...
On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:
wrote in message news
Or think you do.
It surprises me how many people can\'t.
Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.
I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).
if it takes so long to make that the patent is expired before it is
done
why bother
Right. As people copy your designs, just stay a generation ahead.
Designing is fun. Patent applications aren\'t fun.
I agree. Patent applications are stunningly daunting.
.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...
The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...
...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...
Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!
Since it\'s patented, please tell us how it works!
So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...
The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.
A diff pair can only take about 50mV max whatever the gain control tail
current does.
Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.
Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.
Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.
The 1st application actually got rejected, not surprisingly, the idea of
using S curves to compensate processes had already been
patented...However very surprisingly, our man reworked it to make it
more specific and bobs your uncle....
For me, what is significant is that.....
Usually, top brass pass down the chain decide what they want to produce,
and the surfs churn the handle for them.
In this case, I was pondering the problem of poor yields due to the
variability of the xtals and the knowledge of Gilberts technique popped
up in my noggin as a solution. I explained the idea to my local work
mates, we did some simulations with real xtal data and tanh() in Excel
and convinced ourselves that it would work. We presented the idea to top
brass and they said go ahead, make a test ASIC. Although a few teething
issues with the ASIC, it worked well enough to prove the concept worked.
So, this is a method that should give at least a 5 times improvment in
temperature stability, yet originated from a surf with no remit....
Well, get out the serfboard and celebrate.
That\'s a cute technique, thanks. My underwater projects are always the
best too.
Cheers
Phil Hobbs
Given that you can approximate a function out of N piecewise segments
of arbitrary length and slope, is there a process to locate the
segment endpoints for minimum (peak or RMS maybe) error? I usually do
it by eyeball but there must be a better way.
Yes. There is. The \"piecewise\" bit was a key issue being solved though. One
needs a smooth transition to get a low dV/dT slope. The slope error is
typically more of a problem for the frequency stability that the actual
stability itself
Overlapped TANHs is cute. One could slide them around (offset) and
adjust their slopes (tail currents).
Exactly. The blocks have programmable slope, offsets and max current, with
polarity.
One uses the solver in Excel!
One constructs a table with the data of the curve that is to be compensated.
Then construct a sum of tanh() functions with co-efficients
A_n.tanh(B_n.T+C_n)
One tells Excel to find the best co-efficients that minimises the summed
squared error of the original function and the approximating function.
Its really simple. One just selects the co-efficients to be varied and Excel
just churns out the answer. No math knowledge is required at all.
It practice, one actually uses measured data tables from the blocks. It
doesn\'t actually matter what the exact shape is so long as it is S like.
-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html