JL wrote an interesting post in the depths of the "better microelectronics from coal" thread that I thought was worth pulling out on its own. On 2024-01-21 10:12, John Larkin wrote:> "...what IS electronic > design, and what's the best way to do it? <snip> > > Short answer, cobbling. When presented with a problem or an > opportunity to design electronics, the most efficient way to do that > is to grab a piece of paper and immediately sketch a circuit or an > assembly. Sometimes one can do that instantly, without thinking, or > sometimes one can ignore the issue for a few days and then the design > pops up. Sometimes brainstorming and whiteboarding help. Sometimes > fiddling with Spice helps. > > All that literature research and math analysis and simulation and > breadboarding and prototyping are just slow and expensive follow-up > chores for people who don't have 100% confidence in their instincts. > Analysis, sometimes prudent to do, but not design. > > Design is subconsious and instinctive. And it's free! And to some > extent, it can be taught, but seldom is. > > Most of us design things to sell, so do whatever works. We're selling > stuff, not publishing papers. > Hmm. I don't think that I agree in general, because you make it sound as though the process were just intuitively plucking one idea out of somewhere-or-other and cranking it out. You've often argued in favor of brainstorming, where you get a few smart people in front of a white board and try out ideas to find the best one and flesh it out. We've done that together, very fruitfully. It's possible to do more or less the same thing by oneself, but it requires the ability to tolerate uncertainty for extended periods. (That's a skill well worth developing, which most people are really, really bad at, IME.) I sometimes need to do a family of designs, rather than just one. Recently I've been working on some very fast, very cheap SPAD preamps, intended to go in the guts of positron-emission scanners. Designs with lots of real-world constraints are often the most fun, and this one's specs include: 300-ps edges with 100-ps timing repeatability from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. (You need a whole lot of channels, and PET and MRI machines are often combined.) I do a fair amount of analysis of circuits of that sort, to figure out what actually limits their performance. It isn't super detailed--in this case, just enough to figure out whether it'll be the base-emitter time constant, the Miller effect, or the SPAD's series resistance that will be the limiting factor. Miller, I can deal with using circuit hacks. The BE time constant is Rbb' * Cbe, which gets slightly worse at high current, but is mainly a device parameter--to get a big improvement you have to change transistors. The SPAD can be negotiable depending on whose process you're making them on--when each machine needs thousands of them, vendors tend to listen. Eventually, of course, you have to pick one and go with it, but picking a topology usually takes me an iteration or two. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Electronic design
Started by ●January 21, 2024
Reply by ●January 21, 20242024-01-21
On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>JL wrote an interesting post in the depths of the "better >microelectronics from coal" thread that I thought was worth pulling out >on its own. > >On 2024-01-21 10:12, John Larkin wrote:> > >"...what IS electronic > > design, and what's the best way to do it? <snip> > > > > Short answer, cobbling. When presented with a problem or an > > opportunity to design electronics, the most efficient way to do that > > is to grab a piece of paper and immediately sketch a circuit or an > > assembly. Sometimes one can do that instantly, without thinking, or > > sometimes one can ignore the issue for a few days and then the design > > pops up. Sometimes brainstorming and whiteboarding help. Sometimes > > fiddling with Spice helps. > > > > All that literature research and math analysis and simulation and > > breadboarding and prototyping are just slow and expensive follow-up > > chores for people who don't have 100% confidence in their instincts. > > Analysis, sometimes prudent to do, but not design. > > > > Design is subconsious and instinctive. And it's free! And to some > > extent, it can be taught, but seldom is. > > > > Most of us design things to sell, so do whatever works. We're selling > > stuff, not publishing papers. > > > >Hmm. I don't think that I agree in general, because you make it sound >as though the process were just intuitively plucking one idea out of >somewhere-or-other and cranking it out.If an idea is new, where else would come from?> >You've often argued in favor of brainstorming, where you get a few smart >people in front of a white board and try out ideas to find the best one >and flesh it out. We've done that together, very fruitfully. > >It's possible to do more or less the same thing by oneself, but it >requires the ability to tolerate uncertainty for extended periods. >(That's a skill well worth developing, which most people are really, >really bad at, IME.)The uncertainty period is probably necessary, to let ones neurons prowl the noisy solution space. The period is usually a day or two, but can be years. Some engineers are uncomfortable with uncertainty, and want to lock down a design as soon as possible, preferably something sanctioned by some authority. I like to stay confused for a while.> >I sometimes need to do a family of designs, rather than just one. >Recently I've been working on some very fast, very cheap SPAD preamps, >intended to go in the guts of positron-emission scanners. > >Designs with lots of real-world constraints are often the most fun, and >this one's specs include: 300-ps edges with 100-ps timing repeatability >from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. >(You need a whole lot of channels, and PET and MRI machines are often >combined.) > >I do a fair amount of analysis of circuits of that sort, to figure out >what actually limits their performance. It isn't super detailed--in >this case, just enough to figure out whether it'll be the base-emitter >time constant, the Miller effect, or the SPAD's series resistance that >will be the limiting factor.Certainly quantitative reality should filter the solution space. But even that can be mostly intuitive. I was talking about that with C on Friday, about how some people have good quantitative intuition and some don't. She can look at soup in a round pot and know if it will fit into a square plastic container, to about 10%. I can do that. Neither of our spouses can.> >Miller, I can deal with using circuit hacks. The BE time constant is >Rbb' * Cbe, which gets slightly worse at high current, but is mainly a >device parameter--to get a big improvement you have to change >transistors. The SPAD can be negotiable depending on whose process >you're making them on--when each machine needs thousands of them, >vendors tend to listen. > >Eventually, of course, you have to pick one and go with it, but picking >a topology usually takes me an iteration or two.Sometimes a circuit takes me dozens, lots of sheets in the trash can. I think it's important to give as many ideas as possible a chance. See Barrie Gilbert's essay "Where do little circuits come from?" "Prod and poke" and "doodling" are suggested.> >Cheers > >Phil Hobbs
Reply by ●January 21, 20242024-01-21
On Monday, January 22, 2024 at 10:16:12 AM UTC+11, Phil Hobbs wrote:> JL wrote an interesting post in the depths of the "better > microelectronics from coal" thread that I thought was worth pulling out > on its own. > > On 2024-01-21 10:12, John Larkin wrote:> > > "...what IS electronic > > design, and what's the best way to do it? <snip> > > > > Short answer, cobbling. When presented with a problem or an > > opportunity to design electronics, the most efficient way to do that > > is to grab a piece of paper and immediately sketch a circuit or an > > assembly."Efficiency" is a ratio of a theoretically known best way of doing something with what actually happens. There's no theory that can let you work out the "best" design for any particular application, so it's not a word that meas anything useful i this context. In my experience the first step in any design is to work out exactly what you want to happen. Then you have to think of ways of making it happen. Sometimes there's an obvious solution - if you are answering a frequently asked question there's often a frequently adopted solution. New components can suggest solutions that weren't previously practical.> > Sometimes one can do that instantly, without thinking, or > > sometimes one can ignore the issue for a few days and then the design > > pops up. Sometimes brainstorming and whiteboarding help. Sometimes > > fiddling with Spice helps.Thinking about the problem always helps. Conscious thought can often kick the sub-conscious into action, and solutions can pop up from there, but you have to put in the conscious effort to get the process started.> > > All that literature research and math analysis and simulation and > > breadboarding and prototyping are just slow and expensive follow-up > > chores for people who don't have 100% confidence in their instincts.Sane people. For me the hall-mark of actual design is the process of discarding one approach and trying another. John Larkin never talks about that. It's not fun, and it doesn't make you look good, but it does clarify your thinking and let you hone in on what really matters.> > Analysis, sometimes prudent to do, but not design.Not John Larkin's idea of design, which is idiosycratic.> > Design is subconsious and instinctive. And it's free! And to some > > extent, it can be taught, but seldom is.Design can go on in the subconscious, but it isn't free. Waking up in the middle of the night and feeling the urge to sketch a circuit diagram isn't something that makes your wife happy.> > > > Most of us design things to sell, so do whatever works. We're selling > > stuff, not publishing papers.If you have got something unique to sell. writing a paper about it is useful publicity. The instrument literature exists to inform people about solutions that people have worked up to solve academically interesting problems, but most of them are commercially interesting problems as well.> Hmm. I don't think that I agree in general, because you make it sound > as though the process were just intuitively plucking one idea out of > somewhere-or-other and cranking it out.I don't think that John Larkin actually does circuit design in the way that most people understand process. A great many circuits are produced by evolution rather than intelligent design. and quite a few of them work really well. Quite a few more can work better (and be built more cheaply) if you spend some time thinking about what they are doing. I spent about half my time industry doing just that.> You've often argued in favor of brainstorming, where you get a few smart > people in front of a white board and try out ideas to find the best one > and flesh it out. We've done that together, very fruitfully. > > It's possible to do more or less the same thing by oneself, but it > requires the ability to tolerate uncertainty for extended periods. > (That's a skill well worth developing, which most people are really, > really bad at, IME.) > > I sometimes need to do a family of designs, rather than just one. > Recently I've been working on some very fast, very cheap SPAD preamps, > intended to go in the guts of positron-emission scanners. > > Designs with lots of real-world constraints are often the most fun, and > this one's specs include: 300-ps edges with 100-ps timing repeatability > from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. > (You need a whole lot of channels, and PET and MRI machines are often > combined.) > > I do a fair amount of analysis of circuits of that sort, to figure out > what actually limits their performance. It isn't super detailed--in > this case, just enough to figure out whether it'll be the base-emitter > time constant, the Miller effect, or the SPAD's series resistance that > will be the limiting factor. > > Miller, I can deal with using circuit hacks. The BE time constant is > Rbb' * Cbe, which gets slightly worse at high current, but is mainly a > device parameter--to get a big improvement you have to change > transistors. The SPAD can be negotiable depending on whose process > you're making them on--when each machine needs thousands of them, > vendors tend to listen.If you can buy a 100,000 parts you can go for an application specific device.> Eventually, of course, you have to pick one and go with it, but picking > a topology usually takes me an iteration or two.My experience too. -- Bill Sloman, Sydney
Reply by ●January 21, 20242024-01-21
On Monday, January 22, 2024 at 11:06:28 AM UTC+11, John Larkin wrote:> On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote:<snip>> >Hmm. I don't think that I agree in general, because you make it sound > >as though the process were just intuitively plucking one idea out of > >somewhere-or-other and cranking it out. > > If an idea is new, where else would come from?Several people seem to patent the same idea at much the same time. On at least one occasion I knew exactly why - and could put my finger on the paper that had inspired me and the guy who had got there first - who turned out to have edited the journal that published the paper, and had had to put in quite a lot of work to get the author to get the bugs out of the paper> >You've often argued in favor of brainstorming, where you get a few smart > >people in front of a white board and try out ideas to find the best one > >and flesh it out. We've done that together, very fruitfully. > > > >It's possible to do more or less the same thing by oneself, but it > >requires the ability to tolerate uncertainty for extended periods. > >(That's a skill well worth developing, which most people are really, > >really bad at, IME.) > > The uncertainty period is probably necessary, to let ones neurons > prowl the noisy solution space.Neurons don't prowl. They accept inputs and generate outputs which they pass on to other neurons. Look up neural nets sometime.> The period is usually a day or two, but can be years.Years usually means that the technology has had a chance to move on. A good idea I had in 1975 had to wait until 1993 until I could get my hands on a big-enough cheap programmable device to make it work cheaply.> Some engineers are uncomfortable with uncertainty, and want to lock > down a design as soon as possible, preferably something sanctioned by > some authority. I like to stay confused for a while.Making a virtue of necessity, <snip>> Sometimes a circuit takes me dozens, lots of sheets in the trash can. > I think it's important to give as many ideas as possible a chance.There are an infinite number of ideas. You do have to be selective.> See Barrie Gilbert's essay "Where do little circuits come from?" > > "Prod and poke" and "doodling" are suggested.Whatever works for you. -- Bill Sloman, Sydney
Reply by ●January 21, 20242024-01-21
On Sun, 21 Jan 2024 16:05:07 -0800, John Larkin <jl@997PotHill.com> wrote:>On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote: > >>JL wrote an interesting post in the depths of the "better >>microelectronics from coal" thread that I thought was worth pulling out >>on its own. >> >>On 2024-01-21 10:12, John Larkin wrote:> >> >>"...what IS electronic >> > design, and what's the best way to do it? <snip> >> > >> > Short answer, cobbling. When presented with a problem or an >> > opportunity to design electronics, the most efficient way to do that >> > is to grab a piece of paper and immediately sketch a circuit or an >> > assembly. Sometimes one can do that instantly, without thinking, or >> > sometimes one can ignore the issue for a few days and then the design >> > pops up. Sometimes brainstorming and whiteboarding help. Sometimes >> > fiddling with Spice helps. >> > >> > All that literature research and math analysis and simulation and >> > breadboarding and prototyping are just slow and expensive follow-up >> > chores for people who don't have 100% confidence in their instincts. >> > Analysis, sometimes prudent to do, but not design. >> > >> > Design is subconsious and instinctive. And it's free! And to some >> > extent, it can be taught, but seldom is. >> > >> > Most of us design things to sell, so do whatever works. We're selling >> > stuff, not publishing papers. >> > >> >>Hmm. I don't think that I agree in general, because you make it sound >>as though the process were just intuitively plucking one idea out of >>somewhere-or-other and cranking it out. > >If an idea is new, where else would come from?It's the same idea that your FNG suggested in the design review two weeks ago; the one that you shot down in flames. RL
Reply by ●January 21, 20242024-01-21
On Sun, 21 Jan 2024 19:38:37 -0500, legg <legg@nospam.magma.ca> wrote:>On Sun, 21 Jan 2024 16:05:07 -0800, John Larkin <jl@997PotHill.com> >wrote: > >>On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs >><pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>>JL wrote an interesting post in the depths of the "better >>>microelectronics from coal" thread that I thought was worth pulling out >>>on its own. >>> >>>On 2024-01-21 10:12, John Larkin wrote:> >>> >>>"...what IS electronic >>> > design, and what's the best way to do it? <snip> >>> > >>> > Short answer, cobbling. When presented with a problem or an >>> > opportunity to design electronics, the most efficient way to do that >>> > is to grab a piece of paper and immediately sketch a circuit or an >>> > assembly. Sometimes one can do that instantly, without thinking, or >>> > sometimes one can ignore the issue for a few days and then the design >>> > pops up. Sometimes brainstorming and whiteboarding help. Sometimes >>> > fiddling with Spice helps. >>> > >>> > All that literature research and math analysis and simulation and >>> > breadboarding and prototyping are just slow and expensive follow-up >>> > chores for people who don't have 100% confidence in their instincts. >>> > Analysis, sometimes prudent to do, but not design. >>> > >>> > Design is subconsious and instinctive. And it's free! And to some >>> > extent, it can be taught, but seldom is. >>> > >>> > Most of us design things to sell, so do whatever works. We're selling >>> > stuff, not publishing papers. >>> > >>> >>>Hmm. I don't think that I agree in general, because you make it sound >>>as though the process were just intuitively plucking one idea out of >>>somewhere-or-other and cranking it out. >> >>If an idea is new, where else would come from? > >It's the same idea that your FNG suggested in the design review >two weeks ago; the one that you shot down in flames. > >RLWhat's an FNG? But yes, people are sometimes resistant to new ideas but if you don't push too hard, they may come around in time, and maybe think it is their idea. It's best to not shoot down ideas unless they are really impossible. But if played with, they might lead to something good.
Reply by ●January 21, 20242024-01-21
On Sun, 21 Jan 2024 16:05:07 -0800, John Larkin <jl@997PotHill.com> wrote:>On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote: > >>JL wrote an interesting post in the depths of the "better >>microelectronics from coal" thread that I thought was worth pulling out >>on its own. >> >>On 2024-01-21 10:12, John Larkin wrote:> >> >>"...what IS electronic >> > design, and what's the best way to do it? <snip> >> > >> > Short answer, cobbling. When presented with a problem or an >> > opportunity to design electronics, the most efficient way to do that >> > is to grab a piece of paper and immediately sketch a circuit or an >> > assembly. Sometimes one can do that instantly, without thinking, or >> > sometimes one can ignore the issue for a few days and then the design >> > pops up. Sometimes brainstorming and whiteboarding help. Sometimes >> > fiddling with Spice helps. >> > >> > All that literature research and math analysis and simulation and >> > breadboarding and prototyping are just slow and expensive follow-up >> > chores for people who don't have 100% confidence in their instincts. >> > Analysis, sometimes prudent to do, but not design. >> > >> > Design is subconsious and instinctive. And it's free! And to some >> > extent, it can be taught, but seldom is. >> > >> > Most of us design things to sell, so do whatever works. We're selling >> > stuff, not publishing papers. >> > >> >>Hmm. I don't think that I agree in general, because you make it sound >>as though the process were just intuitively plucking one idea out of >>somewhere-or-other and cranking it out. > >If an idea is new, where else would come from? > >> >>You've often argued in favor of brainstorming, where you get a few smart >>people in front of a white board and try out ideas to find the best one >>and flesh it out. We've done that together, very fruitfully. >> >>It's possible to do more or less the same thing by oneself, but it >>requires the ability to tolerate uncertainty for extended periods. >>(That's a skill well worth developing, which most people are really, >>really bad at, IME.) > >The uncertainty period is probably necessary, to let ones neurons >prowl the noisy solution space. The period is usually a day or two, >but can be years. > >Some engineers are uncomfortable with uncertainty, and want to lock >down a design as soon as possible, preferably something sanctioned by >some authority. I like to stay confused for a while. > >> >>I sometimes need to do a family of designs, rather than just one. >>Recently I've been working on some very fast, very cheap SPAD preamps, >>intended to go in the guts of positron-emission scanners. >> >>Designs with lots of real-world constraints are often the most fun, and >>this one's specs include: 300-ps edges with 100-ps timing repeatability >>from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. >>(You need a whole lot of channels, and PET and MRI machines are often >>combined.) >> >>I do a fair amount of analysis of circuits of that sort, to figure out >>what actually limits their performance. It isn't super detailed--in >>this case, just enough to figure out whether it'll be the base-emitter >>time constant, the Miller effect, or the SPAD's series resistance that >>will be the limiting factor. > >Certainly quantitative reality should filter the solution space. But >even that can be mostly intuitive. I was talking about that with C on >Friday, about how some people have good quantitative intuition and >some don't. She can look at soup in a round pot and know if it will >fit into a square plastic container, to about 10%. I can do that. >Neither of our spouses can. > > >> >>Miller, I can deal with using circuit hacks. The BE time constant is >>Rbb' * Cbe, which gets slightly worse at high current, but is mainly a >>device parameter--to get a big improvement you have to change >>transistors. The SPAD can be negotiable depending on whose process >>you're making them on--when each machine needs thousands of them, >>vendors tend to listen. >> >>Eventually, of course, you have to pick one and go with it, but picking >>a topology usually takes me an iteration or two. > >Sometimes a circuit takes me dozens, lots of sheets in the trash can. >I think it's important to give as many ideas as possible a chance. > >See Barrie Gilbert's essay "Where do little circuits come from?" > >"Prod and poke" and "doodling" are suggested. >I agree with both of you. What Phil is doing is figuring out where to focus the brainstorming and fiddling, and the resulting wild alternatives can easily be assessed. It's at the very least an orthogonal method. My personal experience is that iterations and inspirations require studying extensively followed by sleeping on it, so the metric isn't a few days, it's a few nights. The bit about the necessity of nights was pointed out by J. Hadamard in his famous book on this issue. The book has become hard to find and expensive, but has now been reissued: .<https://www.amazon.com/Mathematicians-Mind-Jacques-Hadamard/dp/0691029318/ref=sr_1_1> Joe Gwinn
Reply by ●January 21, 20242024-01-21
On Sun, 21 Jan 2024 22:08:08 -0500, Joe Gwinn <joegwinn@comcast.net> wrote:>On Sun, 21 Jan 2024 16:05:07 -0800, John Larkin <jl@997PotHill.com> >wrote: > >>On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs >><pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>>JL wrote an interesting post in the depths of the "better >>>microelectronics from coal" thread that I thought was worth pulling out >>>on its own. >>> >>>On 2024-01-21 10:12, John Larkin wrote:> >>> >>>"...what IS electronic >>> > design, and what's the best way to do it? <snip> >>> > >>> > Short answer, cobbling. When presented with a problem or an >>> > opportunity to design electronics, the most efficient way to do that >>> > is to grab a piece of paper and immediately sketch a circuit or an >>> > assembly. Sometimes one can do that instantly, without thinking, or >>> > sometimes one can ignore the issue for a few days and then the design >>> > pops up. Sometimes brainstorming and whiteboarding help. Sometimes >>> > fiddling with Spice helps. >>> > >>> > All that literature research and math analysis and simulation and >>> > breadboarding and prototyping are just slow and expensive follow-up >>> > chores for people who don't have 100% confidence in their instincts. >>> > Analysis, sometimes prudent to do, but not design. >>> > >>> > Design is subconsious and instinctive. And it's free! And to some >>> > extent, it can be taught, but seldom is. >>> > >>> > Most of us design things to sell, so do whatever works. We're selling >>> > stuff, not publishing papers. >>> > >>> >>>Hmm. I don't think that I agree in general, because you make it sound >>>as though the process were just intuitively plucking one idea out of >>>somewhere-or-other and cranking it out. >> >>If an idea is new, where else would come from? >> >>> >>>You've often argued in favor of brainstorming, where you get a few smart >>>people in front of a white board and try out ideas to find the best one >>>and flesh it out. We've done that together, very fruitfully. >>> >>>It's possible to do more or less the same thing by oneself, but it >>>requires the ability to tolerate uncertainty for extended periods. >>>(That's a skill well worth developing, which most people are really, >>>really bad at, IME.) >> >>The uncertainty period is probably necessary, to let ones neurons >>prowl the noisy solution space. The period is usually a day or two, >>but can be years. >> >>Some engineers are uncomfortable with uncertainty, and want to lock >>down a design as soon as possible, preferably something sanctioned by >>some authority. I like to stay confused for a while. >> >>> >>>I sometimes need to do a family of designs, rather than just one. >>>Recently I've been working on some very fast, very cheap SPAD preamps, >>>intended to go in the guts of positron-emission scanners. >>> >>>Designs with lots of real-world constraints are often the most fun, and >>>this one's specs include: 300-ps edges with 100-ps timing repeatability >>>from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. >>>(You need a whole lot of channels, and PET and MRI machines are often >>>combined.) >>> >>>I do a fair amount of analysis of circuits of that sort, to figure out >>>what actually limits their performance. It isn't super detailed--in >>>this case, just enough to figure out whether it'll be the base-emitter >>>time constant, the Miller effect, or the SPAD's series resistance that >>>will be the limiting factor. >> >>Certainly quantitative reality should filter the solution space. But >>even that can be mostly intuitive. I was talking about that with C on >>Friday, about how some people have good quantitative intuition and >>some don't. She can look at soup in a round pot and know if it will >>fit into a square plastic container, to about 10%. I can do that. >>Neither of our spouses can. >> >> >>> >>>Miller, I can deal with using circuit hacks. The BE time constant is >>>Rbb' * Cbe, which gets slightly worse at high current, but is mainly a >>>device parameter--to get a big improvement you have to change >>>transistors. The SPAD can be negotiable depending on whose process >>>you're making them on--when each machine needs thousands of them, >>>vendors tend to listen. >>> >>>Eventually, of course, you have to pick one and go with it, but picking >>>a topology usually takes me an iteration or two. >> >>Sometimes a circuit takes me dozens, lots of sheets in the trash can. >>I think it's important to give as many ideas as possible a chance. >> >>See Barrie Gilbert's essay "Where do little circuits come from?" >> >>"Prod and poke" and "doodling" are suggested. >> > >I agree with both of you. What Phil is doing is figuring out where to >focus the brainstorming and fiddling, and the resulting wild >alternatives can easily be assessed. It's at the very least an >orthogonal method. > >My personal experience is that iterations and inspirations require >studying extensively followed by sleeping on it, so the metric isn't a >few days, it's a few nights.Actually, it is a few showers.> >The bit about the necessity of nights was pointed out by J. Hadamard >in his famous book on this issue. The book has become hard to find >and expensive, but has now been reissued: > >.<https://www.amazon.com/Mathematicians-Mind-Jacques-Hadamard/dp/0691029318/ref=sr_1_1> > >Joe Gwinn
Reply by ●January 22, 20242024-01-22
On Sun, 21 Jan 2024 19:43:18 -0800, John Larkin <jl@997PotHill.com> wrote:>On Sun, 21 Jan 2024 22:08:08 -0500, Joe Gwinn <joegwinn@comcast.net> >wrote: > >>On Sun, 21 Jan 2024 16:05:07 -0800, John Larkin <jl@997PotHill.com> >>wrote: >> >>>On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs >>><pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>>JL wrote an interesting post in the depths of the "better >>>>microelectronics from coal" thread that I thought was worth pulling out >>>>on its own. >>>> >>>>On 2024-01-21 10:12, John Larkin wrote:> >>>> >>>>"...what IS electronic >>>> > design, and what's the best way to do it? <snip> >>>> > >>>> > Short answer, cobbling. When presented with a problem or an >>>> > opportunity to design electronics, the most efficient way to do that >>>> > is to grab a piece of paper and immediately sketch a circuit or an >>>> > assembly. Sometimes one can do that instantly, without thinking, or >>>> > sometimes one can ignore the issue for a few days and then the design >>>> > pops up. Sometimes brainstorming and whiteboarding help. Sometimes >>>> > fiddling with Spice helps. >>>> > >>>> > All that literature research and math analysis and simulation and >>>> > breadboarding and prototyping are just slow and expensive follow-up >>>> > chores for people who don't have 100% confidence in their instincts. >>>> > Analysis, sometimes prudent to do, but not design. >>>> > >>>> > Design is subconsious and instinctive. And it's free! And to some >>>> > extent, it can be taught, but seldom is. >>>> > >>>> > Most of us design things to sell, so do whatever works. We're selling >>>> > stuff, not publishing papers. >>>> > >>>> >>>>Hmm. I don't think that I agree in general, because you make it sound >>>>as though the process were just intuitively plucking one idea out of >>>>somewhere-or-other and cranking it out. >>> >>>If an idea is new, where else would come from? >>> >>>> >>>>You've often argued in favor of brainstorming, where you get a few smart >>>>people in front of a white board and try out ideas to find the best one >>>>and flesh it out. We've done that together, very fruitfully. >>>> >>>>It's possible to do more or less the same thing by oneself, but it >>>>requires the ability to tolerate uncertainty for extended periods. >>>>(That's a skill well worth developing, which most people are really, >>>>really bad at, IME.) >>> >>>The uncertainty period is probably necessary, to let ones neurons >>>prowl the noisy solution space. The period is usually a day or two, >>>but can be years. >>> >>>Some engineers are uncomfortable with uncertainty, and want to lock >>>down a design as soon as possible, preferably something sanctioned by >>>some authority. I like to stay confused for a while. >>> >>>> >>>>I sometimes need to do a family of designs, rather than just one. >>>>Recently I've been working on some very fast, very cheap SPAD preamps, >>>>intended to go in the guts of positron-emission scanners. >>>> >>>>Designs with lots of real-world constraints are often the most fun, and >>>>this one's specs include: 300-ps edges with 100-ps timing repeatability >>>>from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. >>>>(You need a whole lot of channels, and PET and MRI machines are often >>>>combined.) >>>> >>>>I do a fair amount of analysis of circuits of that sort, to figure out >>>>what actually limits their performance. It isn't super detailed--in >>>>this case, just enough to figure out whether it'll be the base-emitter >>>>time constant, the Miller effect, or the SPAD's series resistance that >>>>will be the limiting factor. >>> >>>Certainly quantitative reality should filter the solution space. But >>>even that can be mostly intuitive. I was talking about that with C on >>>Friday, about how some people have good quantitative intuition and >>>some don't. She can look at soup in a round pot and know if it will >>>fit into a square plastic container, to about 10%. I can do that. >>>Neither of our spouses can. >>> >>> >>>> >>>>Miller, I can deal with using circuit hacks. The BE time constant is >>>>Rbb' * Cbe, which gets slightly worse at high current, but is mainly a >>>>device parameter--to get a big improvement you have to change >>>>transistors. The SPAD can be negotiable depending on whose process >>>>you're making them on--when each machine needs thousands of them, >>>>vendors tend to listen. >>>> >>>>Eventually, of course, you have to pick one and go with it, but picking >>>>a topology usually takes me an iteration or two. >>> >>>Sometimes a circuit takes me dozens, lots of sheets in the trash can. >>>I think it's important to give as many ideas as possible a chance. >>> >>>See Barrie Gilbert's essay "Where do little circuits come from?" >>> >>>"Prod and poke" and "doodling" are suggested. >>> >> >>I agree with both of you. What Phil is doing is figuring out where to >>focus the brainstorming and fiddling, and the resulting wild >>alternatives can easily be assessed. It's at the very least an >>orthogonal method. >> >>My personal experience is that iterations and inspirations require >>studying extensively followed by sleeping on it, so the metric isn't a >>few days, it's a few nights. > >Actually, it is a few showers.So, you're all wet? Actually, I also get ideas in the shower, probably because I stopped focusing so hard. I used to keep a waterproof dictation recorder handy, and on my bedside table, so I wouldn't lose the ideas, but don't need the recorder any more. But the key is to stop trying for a while and think irrelevant things. Joe Gwinn>>The bit about the necessity of nights was pointed out by J. Hadamard >>in his famous book on this issue. The book has become hard to find >>and expensive, but has now been reissued: >> >>.<https://www.amazon.com/Mathematicians-Mind-Jacques-Hadamard/dp/0691029318/ref=sr_1_1> >> >>Joe Gwinn
Reply by ●January 22, 20242024-01-22
On Mon, 22 Jan 2024 00:12:36 -0500, Joe Gwinn <joegwinn@comcast.net> wrote:>On Sun, 21 Jan 2024 19:43:18 -0800, John Larkin <jl@997PotHill.com> >wrote: > >>On Sun, 21 Jan 2024 22:08:08 -0500, Joe Gwinn <joegwinn@comcast.net> >>wrote: >> >>>On Sun, 21 Jan 2024 16:05:07 -0800, John Larkin <jl@997PotHill.com> >>>wrote: >>> >>>>On Sun, 21 Jan 2024 18:16:01 -0500, Phil Hobbs >>>><pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>>JL wrote an interesting post in the depths of the "better >>>>>microelectronics from coal" thread that I thought was worth pulling out >>>>>on its own. >>>>> >>>>>On 2024-01-21 10:12, John Larkin wrote:> >>>>> >>>>>"...what IS electronic >>>>> > design, and what's the best way to do it? <snip> >>>>> > >>>>> > Short answer, cobbling. When presented with a problem or an >>>>> > opportunity to design electronics, the most efficient way to do that >>>>> > is to grab a piece of paper and immediately sketch a circuit or an >>>>> > assembly. Sometimes one can do that instantly, without thinking, or >>>>> > sometimes one can ignore the issue for a few days and then the design >>>>> > pops up. Sometimes brainstorming and whiteboarding help. Sometimes >>>>> > fiddling with Spice helps. >>>>> > >>>>> > All that literature research and math analysis and simulation and >>>>> > breadboarding and prototyping are just slow and expensive follow-up >>>>> > chores for people who don't have 100% confidence in their instincts. >>>>> > Analysis, sometimes prudent to do, but not design. >>>>> > >>>>> > Design is subconsious and instinctive. And it's free! And to some >>>>> > extent, it can be taught, but seldom is. >>>>> > >>>>> > Most of us design things to sell, so do whatever works. We're selling >>>>> > stuff, not publishing papers. >>>>> > >>>>> >>>>>Hmm. I don't think that I agree in general, because you make it sound >>>>>as though the process were just intuitively plucking one idea out of >>>>>somewhere-or-other and cranking it out. >>>> >>>>If an idea is new, where else would come from? >>>> >>>>> >>>>>You've often argued in favor of brainstorming, where you get a few smart >>>>>people in front of a white board and try out ideas to find the best one >>>>>and flesh it out. We've done that together, very fruitfully. >>>>> >>>>>It's possible to do more or less the same thing by oneself, but it >>>>>requires the ability to tolerate uncertainty for extended periods. >>>>>(That's a skill well worth developing, which most people are really, >>>>>really bad at, IME.) >>>> >>>>The uncertainty period is probably necessary, to let ones neurons >>>>prowl the noisy solution space. The period is usually a day or two, >>>>but can be years. >>>> >>>>Some engineers are uncomfortable with uncertainty, and want to lock >>>>down a design as soon as possible, preferably something sanctioned by >>>>some authority. I like to stay confused for a while. >>>> >>>>> >>>>>I sometimes need to do a family of designs, rather than just one. >>>>>Recently I've been working on some very fast, very cheap SPAD preamps, >>>>>intended to go in the guts of positron-emission scanners. >>>>> >>>>>Designs with lots of real-world constraints are often the most fun, and >>>>>this one's specs include: 300-ps edges with 100-ps timing repeatability >>>>>from unit to unit; no magnetics allowed; and a BOM cost of $1 or less. >>>>>(You need a whole lot of channels, and PET and MRI machines are often >>>>>combined.) >>>>> >>>>>I do a fair amount of analysis of circuits of that sort, to figure out >>>>>what actually limits their performance. It isn't super detailed--in >>>>>this case, just enough to figure out whether it'll be the base-emitter >>>>>time constant, the Miller effect, or the SPAD's series resistance that >>>>>will be the limiting factor. >>>> >>>>Certainly quantitative reality should filter the solution space. But >>>>even that can be mostly intuitive. I was talking about that with C on >>>>Friday, about how some people have good quantitative intuition and >>>>some don't. She can look at soup in a round pot and know if it will >>>>fit into a square plastic container, to about 10%. I can do that. >>>>Neither of our spouses can. >>>> >>>> >>>>> >>>>>Miller, I can deal with using circuit hacks. The BE time constant is >>>>>Rbb' * Cbe, which gets slightly worse at high current, but is mainly a >>>>>device parameter--to get a big improvement you have to change >>>>>transistors. The SPAD can be negotiable depending on whose process >>>>>you're making them on--when each machine needs thousands of them, >>>>>vendors tend to listen. >>>>> >>>>>Eventually, of course, you have to pick one and go with it, but picking >>>>>a topology usually takes me an iteration or two. >>>> >>>>Sometimes a circuit takes me dozens, lots of sheets in the trash can. >>>>I think it's important to give as many ideas as possible a chance. >>>> >>>>See Barrie Gilbert's essay "Where do little circuits come from?" >>>> >>>>"Prod and poke" and "doodling" are suggested. >>>> >>> >>>I agree with both of you. What Phil is doing is figuring out where to >>>focus the brainstorming and fiddling, and the resulting wild >>>alternatives can easily be assessed. It's at the very least an >>>orthogonal method. >>> >>>My personal experience is that iterations and inspirations require >>>studying extensively followed by sleeping on it, so the metric isn't a >>>few days, it's a few nights. >> >>Actually, it is a few showers. > >So, you're all wet?That's the idea.> >Actually, I also get ideas in the shower, probably because I stopped >focusing so hard.I think sleepytime ideas get delivered in a morning shower. I don't have ideas if I shower later in the day.> >I used to keep a waterproof dictation recorder handy, and on my >bedside table, so I wouldn't lose the ideas, but don't need the >recorder any more.Sometimes I have ideas at around 3AM. I scribble them on a pad so I don't forget.> >But the key is to stop trying for a while and think irrelevant things. > >Joe Gwinn > > >>>The bit about the necessity of nights was pointed out by J. Hadamard >>>in his famous book on this issue. The book has become hard to find >>>and expensive, but has now been reissued: >>> >>>.<https://www.amazon.com/Mathematicians-Mind-Jacques-Hadamard/dp/0691029318/ref=sr_1_1> >>> >>>Joe Gwinn
