gwhite wrote:
Kevin Aylward wrote: It is that simple. Nope. Its not. Linearity has many definitions. It doesn't have "many definitions" when it comes to the EE profession. The one definition is wholly consistant across academic texts -- without known contradiction. Everyone who took courses like Circuits, Fields and Waves, and on and on, also took a Signals and Systems (or similar under a different name) course. That some, such as you for example, didn't learn or understand the definition is notwithstanding. Look, I have no problem with your example of a particular definition of linearity. I already explained how such an example is meaningless in analogue design by giving an example. A mathematical definition only has meaning if it is useful when it is applied. In analogue design this definition is useless, so it is not used. It is useful to the extent modulation is a linear operation produced by devices such as gilbert cells biased to Class-A. Look, you don't even realise that you are using "linear" here in a completely different sense then one applies it to an equation. What part of "I agree, that a modulator can be described as a linear process" do you have trouble with.? What part of "A modulater usually achives its function by using a non-linear relation between input voltge/current to output voltage/current do you have trouble with.? In one case "linear" is being applied as a property of system as a whole, in the other it is being applied as a property to an individual component of system. Both statements are correct, in their given contest, but they are saying "different" things. The issue here is that you have parrot read something from a book, and then go applying willy nilly it without even the slightest idea of when it is applicable. Non of the standard references suggest that non-linear equations are linear. This is daft. There are addressing a different matter entirely. I have already explained what the distinction is, you have failed to understand, the point, and I doubt never will. It is very useful definition: for example, high data rate modern digital communications systems routinely utilize linear modulation/demodulation. Of course its useful, assuming you are competent enough to know when it can be applied. It doesn't even matter if the upper transistors in the gilbert cells are driven to the switch mode (switch mode is not a requirement; class-A will do) by the LO. It is still linear modulation. I don't disagree, never claimed otherwise. This is a diffent use of the word linear. However, it achieves its "linear" modulation by non-linear means, which you claim it doesn't. This system is linear: {sniped teaching granny to suck eggs drivial} Do you know why? Yes. I already explained it. You snipped it in my last post. Jesus wept dude. This is bloody ridiculous. Look sonny boy, snipping my detailed explanation of why your modulator can be classed as a linear system, in the given context, shows you for the liar that you are. You don't impress anyone by attempting to prove a result, you have been informed at least twice that, is trivial, and that I had already agreed with that result, in that particular context. I care about linearity as understood in the solution of the non-linear differential equations used in Spice. Like I said early on: you can make the answer come out however you want if you are permitted to make up the rules and change them as you play. The rules have not been changed. Unfortunately you are too incompetent to know when to apply the relevant rules. Show me one Signals, Systems, and Communications text that declares y=x^2 is a linear equation. What part of "apples" and "fishnet stockings" did you have trouble with? Look, I don't claim that the particular definition of linearity that you presence is "wrong" in principle. It is a very well known definition. However, it is one of many, and is simple not applicable in this context. It is the definition for the EE profession. Its apparent you know f'all about definitions in either mathematics or electronics, nor how to apply them. I clearly said that linearity, as defined in analogue design, is essentially defined by the absence of any frequencies in the output not present in the input. That "definition" is incorrect, as has been pointed out already. It is not, as has been pointed out to you already. proof: 1 Go to *any* and *all* main component vendors web site, e.g. TI, Analog Devices, Maxim, LT, National, etc 2 Look at their dat sheets and app notes on A/D D/A converters 3 Note the use of FFT testing for linearity. 4 Note how they *all* declare the linearity of A/D D/A by the level of spurious frequencies *This* is the definitin that is *actually* uesd in the EE profession. Its the way it is, and no amount of your huffing and puffing will change what is standard practise. All you have done here is show that you have not got a clue on what is standard practise in electronic engineer. Your words mean nothing The reality is, is that you are simple trying to hide you failure to show that your class A amplifier cannot achieve modulation without using the non-linear relation of input voltage to current. Its as plain as day. Produce you proof of Vo(t)= Vi(t).(1+a.sin(wt)) or shut the f'ck up. I know all about your definition. I dont disagree that it is a valid definition in some contexts. It is the definition for the EE context. Not in the detailed design of electronic circuits it isn't. If you want an LTI system, then so be it. However, it is not applicable to electronic circuit design that is based on the solution of non-linear differential equations, with the "non-linear" term having a universally accepted meaning by the 10,000s of mathematician who actually study such equations. It is not a matter of a mathematician's characterization of equations. It is the EE characterization, and this is largely an EE forum. If you are a mathematician and not an EE, then I can see why you would believe what you do. Sorry mate, what part of "there are 100,000's of EE's out there using Spice, all on the understanding that the equations of electronic design are non-linear" do you fail to undrstand"? Your a right blooody joke. You particular Mickey mouse, comic book understanding of what constitutes an acceptable definition in EE is irrelevant. We real practicing design engineers don't care about you erroneous waffle. Secondly, there is not a hope in hell that the authors of your quoted references will agree with your gross distortion of their books contents. You have not the slightest ability to apply such knowledge. Your on you own. You arnt wrong in this thread because of you particular claim of linearity. It isn't "my claim." It is your claim. No competent author will claim y=x^2 is a linear equation. Get real. It is the standard definition for EE's. As I explained above, complete an utter nonsense. You haven't the slightest idea of what is standard practise in electronic engineering. I have been an analogue designer for over 20 years, and no one I have met uses your suggestion in the design of circuits. Your definition is more appropriate to complete system design, then discrete component design. That some EE's didn't quite "get it" is notwithstanding. Indeed they dont. You are simple too dense, are are too much of a coward to admit your wrong. I explained in detail the two diffent comcepts of lineararity. The real reason for this disagreement is that you are talking apples and I am talking fish net stockings. You are applying the term linearity in a completely different sense than the one I am using. Both are valid in principle, and are indeed well accepted, under their appropriate conditions. Your definition is not the EE definition. Yes is is. I don't know one competent EE who declares that the transistor equation is a linear equation. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
gwhite wrote:
Kevin Aylward wrote: It is that simple. Nope. Its not. Linearity has many definitions. It doesn't have "many definitions" when it comes to the EE profession. The one definition is wholly consistant across academic texts -- without known contradiction. Everyone who took courses like Circuits, Fields and Waves, and on and on, also took a Signals and Systems (or similar under a different name) course. That some, such as you for example, didn't learn or understand the definition is notwithstanding. Look, I have no problem with your example of a particular definition of linearity. I already explained how such an example is meaningless in analogue design by giving an example. A mathematical definition only has meaning if it is useful when it is applied. In analogue design this definition is useless, so it is not used. It is useful to the extent modulation is a linear operation produced by devices such as gilbert cells biased to Class-A. Look, you don't even realise that you are using "linear" here in a completely different sense then one applies it to an equation. What part of "I agree, that a modulator can be described as a linear process" do you have trouble with.? What part of "A modulater usually achives its function by using a non-linear relation between input voltge/current to output voltage/current do you have trouble with.? In one case "linear" is being applied as a property of system as a whole, in the other it is being applied as a property to an individual component of system. Both statements are correct, in their given contest, but they are saying "different" things. The issue here is that you have parrot read something from a book, and then go applying willy nilly it without even the slightest idea of when it is applicable. Non of the standard references suggest that non-linear equations are linear. This is daft. There are addressing a different matter entirely. I have already explained what the distinction is, you have failed to understand, the point, and I doubt never will. It is very useful definition: for example, high data rate modern digital communications systems routinely utilize linear modulation/demodulation. Of course its useful, assuming you are competent enough to know when it can be applied. It doesn't even matter if the upper transistors in the gilbert cells are driven to the switch mode (switch mode is not a requirement; class-A will do) by the LO. It is still linear modulation. I don't disagree, never claimed otherwise. This is a diffent use of the word linear. However, it achieves its "linear" modulation by non-linear means, which you claim it doesn't. This system is linear: {sniped teaching granny to suck eggs drivial} Do you know why? Yes. I already explained it. You snipped it in my last post. Jesus wept dude. This is bloody ridiculous. Look sonny boy, snipping my detailed explanation of why your modulator can be classed as a linear system, in the given context, shows you for the liar that you are. You don't impress anyone by attempting to prove a result, you have been informed at least twice that, is trivial, and that I had already agreed with that result, in that particular context. I care about linearity as understood in the solution of the non-linear differential equations used in Spice. Like I said early on: you can make the answer come out however you want if you are permitted to make up the rules and change them as you play. The rules have not been changed. Unfortunately you are too incompetent to know when to apply the relevant rules. Show me one Signals, Systems, and Communications text that declares y=x^2 is a linear equation. What part of "apples" and "fishnet stockings" did you have trouble with? Look, I don't claim that the particular definition of linearity that you presence is "wrong" in principle. It is a very well known definition. However, it is one of many, and is simple not applicable in this context. It is the definition for the EE profession. Its apparent you know f'all about definitions in either mathematics or electronics, nor how to apply them. I clearly said that linearity, as defined in analogue design, is essentially defined by the absence of any frequencies in the output not present in the input. That "definition" is incorrect, as has been pointed out already. It is not, as has been pointed out to you already. proof: 1 Go to *any* and *all* main component vendors web site, e.g. TI, Analog Devices, Maxim, LT, National, etc 2 Look at their dat sheets and app notes on A/D D/A converters 3 Note the use of FFT testing for linearity. 4 Note how they *all* declare the linearity of A/D D/A by the level of spurious frequencies *This* is the definitin that is *actually* uesd in the EE profession. Its the way it is, and no amount of your huffing and puffing will change what is standard practise. All you have done here is show that you have not got a clue on what is standard practise in electronic engineer. Your words mean nothing The reality is, is that you are simple trying to hide you failure to show that your class A amplifier cannot achieve modulation without using the non-linear relation of input voltage to current. Its as plain as day. Produce you proof of Vo(t)= Vi(t).(1+a.sin(wt)) or shut the f'ck up. I know all about your definition. I dont disagree that it is a valid definition in some contexts. It is the definition for the EE context. Not in the detailed design of electronic circuits it isn't. If you want an LTI system, then so be it. However, it is not applicable to electronic circuit design that is based on the solution of non-linear differential equations, with the "non-linear" term having a universally accepted meaning by the 10,000s of mathematician who actually study such equations. It is not a matter of a mathematician's characterization of equations. It is the EE characterization, and this is largely an EE forum. If you are a mathematician and not an EE, then I can see why you would believe what you do. Sorry mate, what part of "there are 100,000's of EE's out there using Spice, all on the understanding that the equations of electronic design are non-linear" do you fail to undrstand"? Your a right blooody joke. You particular Mickey mouse, comic book understanding of what constitutes an acceptable definition in EE is irrelevant. We real practicing design engineers don't care about you erroneous waffle. Secondly, there is not a hope in hell that the authors of your quoted references will agree with your gross distortion of their books contents. You have not the slightest ability to apply such knowledge. Your on you own. You arnt wrong in this thread because of you particular claim of linearity. It isn't "my claim." It is your claim. No competent author will claim y=x^2 is a linear equation. Get real. It is the standard definition for EE's. As I explained above, complete an utter nonsense. You haven't the slightest idea of what is standard practise in electronic engineering. I have been an analogue designer for over 20 years, and no one I have met uses your suggestion in the design of circuits. Your definition is more appropriate to complete system design, then discrete component design. That some EE's didn't quite "get it" is notwithstanding. Indeed they dont. You are simple too dense, are are too much of a coward to admit your wrong. I explained in detail the two diffent comcepts of lineararity. The real reason for this disagreement is that you are talking apples and I am talking fish net stockings. You are applying the term linearity in a completely different sense than the one I am using. Both are valid in principle, and are indeed well accepted, under their appropriate conditions. Your definition is not the EE definition. Yes is is. I don't know one competent EE who declares that the transistor equation is a linear equation. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
Paul Burridge wrote:
On Sun, 7 Sep 2003 18:52:46 +0100, "Kevin Aylward" wrote: This results in one main fact. She chooses a mate, essentially, only on the basis of good gene stock. She doesn't want a nice person because this would mean her offspring would also be nice, and thereby do things not in there own best interest. She wants a "mean" offspring. That is, treat them mean, keeps them keen The theories great. It explains quite nicely why women chose those yobbys that beat them up. Can't agree there. Women are basically genetically obliged to pick the best mate they can get their hands on, given the limitations imposed by their own pulling abilities. By and large, this is not significant. The numbers can be increased by quality or quantity. A man will have sex pretty much with *any* women, so long as they're not fat:-). If a women goes up to a man stranger, in a pub and says, lets go back to my place, its a done deal. There is no much of a disadvage numbers wise, a man has offspring by every women he can so he does. On the over hand, a women can not do this. Once she's pregnant, that's her out of the game for 9 months. The only way she can get her genes to replicate faster is by choosing better gene stock. This makes her absolutely choosy. What they are looking for in every case is a mate who can give their offspring the best chance of survival and 'thrival' in this wide, mean world. I think you have still missed an important point here. Yes, I agree that there is some truth in this, and this is a pretty obvious analysis, but it is not that significant. The most important facter is good gene stock. Its the only factor. She will chose a mate based on what characteristics the offspring will have. Not what's in her personal best interest. The body is only a vehicle for the genes. Bodies don't copy themselves, so cant form a basis for replication, only genes replicate. If it is the net best interest of the genes, they will sacrifice the vehicle to enable better success for themselves. Interestingly enough, the qualities the male must display to succeed change according to different ages (historical ages, not biological) and cultures. At varying times, men have been favoured because of, for example, they're exceptionally good fighters. Or unusually good hunters... later in history, we see female preferences based on wealth and status. But in countries where for idealogical reasons, all people are 'made to be equal' like the old Soviet Union or the 'old' China, females must pick according to other criteria such as a gift for literature, music or art. They're all programmed to do their best for the unborn child, even if they don't want children at all or are too old to conceive. But in practice, the single most significant aspect, even today, is physical appearance. It has to be. Its pretty much universal what is considered good looking, many studies have been done. Sure, its useful to have other aspects. A show of wealth, is obviously an indicator that her offspring may also get this characteristic (ignoring the details of how for now), but in pracise, you have to be pretty damn weathy if you want to take Liz Harley to bed. I don't agree. Reviews mean f'all. Have you actually read all the "review" on the later editions of Hawking's "Brief history of time". It make you want to vomit. Sure, his a very clever dude, but he is ceratyinly not a god. I didn't say he was. In fact he admitted to wasting much time working on 'singularities' with Roger Penrose donkey's years ago. As noted above, it was the selfish gene that revolutionised the approach to evolution as to the body being a mere vehicle for the masters, the genes and memes. Let's just put it down to a matter of personal preference, then. [not particularly relevant Einstein example snipped] Oh? The whole emphases on Darwin is wrong, it is a legacy theory. The fundamental idea is the Replicator, as such, a "handicap" is just a specific detail of how some particular Replicators can replicate better. I'm not sure what you're driving at here but I don't like the sound of it. That's because you didn't see the point of the Einstein example. Go back and read it again to get the *bigger* picture. Rubbish. You demonstrably know sweet FA about global economics as demonstrated in our recent exchanges on the subject where you cut and run like a scalded cat when faced with cogent arguments from someone (me) with indisputable expertise in the area. Nonsense. It was just something that I could not be bothered to debate. I have little interest in economics, other than how much I get paid, which concerns me greatly. LOL! Yeah, whatever. You quit while you were behind. You should have quit earlier but I think you just about backed out before you sustained any terminal damage. :-) Nope. I happen to believe in conservation of energy and momentum. You views denied this. I look at the bigger picture. I am not familiar with all the details of economics so I didn't want to get bogged down there. A general theorem that you cant get blood from a stone doesn't need the details, but as I said, cant be bothered expanding on it. If your claiming that Dawkins retracted the basics of Replicators, then your dreaming. I'll have to see what Miller is specifically addressing. I'm suggesting no such thing. I'm simply saying that Dawkins softened his line of selfishness a good measure from the position you wrongly (now) attribute to him. If you mean that we might be able to override the gene's "intentions", I don't know if what he says is really what he believes, or is an attempt to appease the masses for politically correct reasons. The problem is, the only way to override a Replicator, is make a better one. Unfortunately, the ones we have, have millions of years of a head start. You try not getting a hard on if naked striper sits on your lap. I have read a few bits and bobs from creationists who claim that Dawkins recanted on his evolutionary views. It was all crap, as he himself explained. Yes I know. The attempts were laughable. Well, obviously, you could not refute my argument that selfishness is inherent. As I said, its a tautology. It can't be contradicted. Okay, well let's put you this question: if everyone is basically selfish, why do some people help other people out on newsgroups? I explained this, the 5 team bunch of skinheads verses the single guy, although there is a number of factors. The fundermental reason is that the genes expect a payback. Of course, detrimental characteristics are still being randamly generated, so some of them are fools. Have you been to the dawin awards site http://www.darwinawards.com/ ? In *general*, is it good or bad to gain a respected reputation? Genes don't know when helping is going to be beneficial or not, they cant think. They don't know the future. Replication is only based on probabilities. If you help nobody, what's the probability you will get help back? One has to look at the numbers from game theory. Give various traits, e.g helpfulness, punishment, slyness, e.g. tit for tat strategy etc. The final numbers give what strategies are stable, or drive the group to extinction. So, people are helpful to others because, statistically, this strategy results in net benefit to themselves, statisticly. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
Paul Burridge wrote:
On Sun, 7 Sep 2003 18:52:46 +0100, "Kevin Aylward" wrote: This results in one main fact. She chooses a mate, essentially, only on the basis of good gene stock. She doesn't want a nice person because this would mean her offspring would also be nice, and thereby do things not in there own best interest. She wants a "mean" offspring. That is, treat them mean, keeps them keen The theories great. It explains quite nicely why women chose those yobbys that beat them up. Can't agree there. Women are basically genetically obliged to pick the best mate they can get their hands on, given the limitations imposed by their own pulling abilities. By and large, this is not significant. The numbers can be increased by quality or quantity. A man will have sex pretty much with *any* women, so long as they're not fat:-). If a women goes up to a man stranger, in a pub and says, lets go back to my place, its a done deal. There is no much of a disadvage numbers wise, a man has offspring by every women he can so he does. On the over hand, a women can not do this. Once she's pregnant, that's her out of the game for 9 months. The only way she can get her genes to replicate faster is by choosing better gene stock. This makes her absolutely choosy. What they are looking for in every case is a mate who can give their offspring the best chance of survival and 'thrival' in this wide, mean world. I think you have still missed an important point here. Yes, I agree that there is some truth in this, and this is a pretty obvious analysis, but it is not that significant. The most important facter is good gene stock. Its the only factor. She will chose a mate based on what characteristics the offspring will have. Not what's in her personal best interest. The body is only a vehicle for the genes. Bodies don't copy themselves, so cant form a basis for replication, only genes replicate. If it is the net best interest of the genes, they will sacrifice the vehicle to enable better success for themselves. Interestingly enough, the qualities the male must display to succeed change according to different ages (historical ages, not biological) and cultures. At varying times, men have been favoured because of, for example, they're exceptionally good fighters. Or unusually good hunters... later in history, we see female preferences based on wealth and status. But in countries where for idealogical reasons, all people are 'made to be equal' like the old Soviet Union or the 'old' China, females must pick according to other criteria such as a gift for literature, music or art. They're all programmed to do their best for the unborn child, even if they don't want children at all or are too old to conceive. But in practice, the single most significant aspect, even today, is physical appearance. It has to be. Its pretty much universal what is considered good looking, many studies have been done. Sure, its useful to have other aspects. A show of wealth, is obviously an indicator that her offspring may also get this characteristic (ignoring the details of how for now), but in pracise, you have to be pretty damn weathy if you want to take Liz Harley to bed. I don't agree. Reviews mean f'all. Have you actually read all the "review" on the later editions of Hawking's "Brief history of time". It make you want to vomit. Sure, his a very clever dude, but he is ceratyinly not a god. I didn't say he was. In fact he admitted to wasting much time working on 'singularities' with Roger Penrose donkey's years ago. As noted above, it was the selfish gene that revolutionised the approach to evolution as to the body being a mere vehicle for the masters, the genes and memes. Let's just put it down to a matter of personal preference, then. [not particularly relevant Einstein example snipped] Oh? The whole emphases on Darwin is wrong, it is a legacy theory. The fundamental idea is the Replicator, as such, a "handicap" is just a specific detail of how some particular Replicators can replicate better. I'm not sure what you're driving at here but I don't like the sound of it. That's because you didn't see the point of the Einstein example. Go back and read it again to get the *bigger* picture. Rubbish. You demonstrably know sweet FA about global economics as demonstrated in our recent exchanges on the subject where you cut and run like a scalded cat when faced with cogent arguments from someone (me) with indisputable expertise in the area. Nonsense. It was just something that I could not be bothered to debate. I have little interest in economics, other than how much I get paid, which concerns me greatly. LOL! Yeah, whatever. You quit while you were behind. You should have quit earlier but I think you just about backed out before you sustained any terminal damage. :-) Nope. I happen to believe in conservation of energy and momentum. You views denied this. I look at the bigger picture. I am not familiar with all the details of economics so I didn't want to get bogged down there. A general theorem that you cant get blood from a stone doesn't need the details, but as I said, cant be bothered expanding on it. If your claiming that Dawkins retracted the basics of Replicators, then your dreaming. I'll have to see what Miller is specifically addressing. I'm suggesting no such thing. I'm simply saying that Dawkins softened his line of selfishness a good measure from the position you wrongly (now) attribute to him. If you mean that we might be able to override the gene's "intentions", I don't know if what he says is really what he believes, or is an attempt to appease the masses for politically correct reasons. The problem is, the only way to override a Replicator, is make a better one. Unfortunately, the ones we have, have millions of years of a head start. You try not getting a hard on if naked striper sits on your lap. I have read a few bits and bobs from creationists who claim that Dawkins recanted on his evolutionary views. It was all crap, as he himself explained. Yes I know. The attempts were laughable. Well, obviously, you could not refute my argument that selfishness is inherent. As I said, its a tautology. It can't be contradicted. Okay, well let's put you this question: if everyone is basically selfish, why do some people help other people out on newsgroups? I explained this, the 5 team bunch of skinheads verses the single guy, although there is a number of factors. The fundermental reason is that the genes expect a payback. Of course, detrimental characteristics are still being randamly generated, so some of them are fools. Have you been to the dawin awards site http://www.darwinawards.com/ ? In *general*, is it good or bad to gain a respected reputation? Genes don't know when helping is going to be beneficial or not, they cant think. They don't know the future. Replication is only based on probabilities. If you help nobody, what's the probability you will get help back? One has to look at the numbers from game theory. Give various traits, e.g helpfulness, punishment, slyness, e.g. tit for tat strategy etc. The final numbers give what strategies are stable, or drive the group to extinction. So, people are helpful to others because, statistically, this strategy results in net benefit to themselves, statisticly. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
gwhite wrote:
Kevin Aylward wrote: gwhite wrote: Its that simple. I clearly stated that it was *not* a definition. "Linearity can more easily be expressed as: a(f(t)) = f(at)" -- Kevin Aylward I think someone is posting under your name. A nasty bit of business that is. Linearity can be expressed by this, however, it is not a necessary condition. I never claimed that it was a complete definition. It was simply trying to illustrate the concept of constant gain. You expanding on some trivial minor point to avoid answering the main issue, to wit, you have failed to disprove my claim on your class A amplifier. Class A works just fine in multipliers/modulators Never said it didn't. However, the class A bit does not account for how they multiply. -- "non-linearity" of circuit elements is not required. Ho humm. Now for the example that does indeed use non-linearity. Maybe you can analyze the old MC1496. That would be enlightening to you. Yep. Not at all. You are an completly mistaken. It is abundantly clear that you don't know the first thing about analogue circuit design. It is truly amazing and unbelievable that you can be so wrong and not be aware of it. You are an incompetent. The MC1496 is a double balanced modulator based on the Gilbert cell transconductance multiplier. The Gilbert cell multiplier relies on the exponential relation of collector current to base emitter voltage. That is, its transconcutane is a function of its emitter current. Its well understood by all those knowledgeable in the field. to wit: I = Io.exp(V/Vt) transconductance gm = dI/dv = d(Io.exp(V/Vt))/dv gm = Io/Vt.exp(V/Vt)) = Ie/Vt That is, the gm is a function of Ie. Since: Iout = gm.Vin we have Iout = Ie/Vt.Vin That is, Iout is a product of, Ie and Vin. Making Ie a function of another voltage results in the multiplication of two voltages, i.e. a modulator. How you can make such daft claims and not be embarrassed shows greate stamina, I must say. But more important and more simple (it will save you loads of time), just apply *the* linearity test for h(t) x(t) - y(t). You still haveny cottoned on the fact that you wily nilly apply definitions you no hope of understanding. The notion that y=x^2 is a non-linear equation is universally accepted by anyone who has done even the slightest bit of theory on basic algebraic equations. It does not require any qualification in the slightest. No ****, by why are you rambling on and on about it? Because you don't understand it. Show me one, and I mean just one, that declares y=x^2 a linear equation. That is clever -- you want me to "declare" something is true that I've made no reference to. You have. See above. You claimed the Gilbert cell did not rely on non-linearity. Jesus wept again. Your so out to lunch on this that its unreal. Look, own up your just trolling aren't you. You are quite the inventor. Face it: you had an incorrect notion about linearity. Dream on. You have been soundly proven wrong, and why you are wrong. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
gwhite wrote:
Kevin Aylward wrote: gwhite wrote: Its that simple. I clearly stated that it was *not* a definition. "Linearity can more easily be expressed as: a(f(t)) = f(at)" -- Kevin Aylward I think someone is posting under your name. A nasty bit of business that is. Linearity can be expressed by this, however, it is not a necessary condition. I never claimed that it was a complete definition. It was simply trying to illustrate the concept of constant gain. You expanding on some trivial minor point to avoid answering the main issue, to wit, you have failed to disprove my claim on your class A amplifier. Class A works just fine in multipliers/modulators Never said it didn't. However, the class A bit does not account for how they multiply. -- "non-linearity" of circuit elements is not required. Ho humm. Now for the example that does indeed use non-linearity. Maybe you can analyze the old MC1496. That would be enlightening to you. Yep. Not at all. You are an completly mistaken. It is abundantly clear that you don't know the first thing about analogue circuit design. It is truly amazing and unbelievable that you can be so wrong and not be aware of it. You are an incompetent. The MC1496 is a double balanced modulator based on the Gilbert cell transconductance multiplier. The Gilbert cell multiplier relies on the exponential relation of collector current to base emitter voltage. That is, its transconcutane is a function of its emitter current. Its well understood by all those knowledgeable in the field. to wit: I = Io.exp(V/Vt) transconductance gm = dI/dv = d(Io.exp(V/Vt))/dv gm = Io/Vt.exp(V/Vt)) = Ie/Vt That is, the gm is a function of Ie. Since: Iout = gm.Vin we have Iout = Ie/Vt.Vin That is, Iout is a product of, Ie and Vin. Making Ie a function of another voltage results in the multiplication of two voltages, i.e. a modulator. How you can make such daft claims and not be embarrassed shows greate stamina, I must say. But more important and more simple (it will save you loads of time), just apply *the* linearity test for h(t) x(t) - y(t). You still haveny cottoned on the fact that you wily nilly apply definitions you no hope of understanding. The notion that y=x^2 is a non-linear equation is universally accepted by anyone who has done even the slightest bit of theory on basic algebraic equations. It does not require any qualification in the slightest. No ****, by why are you rambling on and on about it? Because you don't understand it. Show me one, and I mean just one, that declares y=x^2 a linear equation. That is clever -- you want me to "declare" something is true that I've made no reference to. You have. See above. You claimed the Gilbert cell did not rely on non-linearity. Jesus wept again. Your so out to lunch on this that its unreal. Look, own up your just trolling aren't you. You are quite the inventor. Face it: you had an incorrect notion about linearity. Dream on. You have been soundly proven wrong, and why you are wrong. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
gwhite wrote:
Frank Raffaeli wrote: gwhite wrote in message ... [snipped long diatribes] Dude, you are responding to one of the shorter messages. Class A works just fine in multipliers/modulators -- "non-linearity" of circuit elements is not required. Maybe you can analyze the old MC1496. That would be enlightening to you. But more important and more simple (it will save you loads of time), just apply *the* linearity test [snip] Hmmm .... you may be mistaking the (sometimes linear) current steering effect for the mechanism within the transistor that makes current steering possible: the relationship between gm and Ic ... or from another POV, the change in rbb with respect to bias current. These effects are non-linear. Non-linearity is *not* required to create DSB-AM out of transconductance type multipliers like the gilbert cell. In fact, *non-linearity is specifically something that designers hope to minimize* -- just like in any linear device. The standard linear approximation practice ensues: that is, the taylor expansion of exp(x) is done and the linear term is the desired one and *it is all that is required or wanted for this linear multiplier*. Ahh... now I see where the confusion is, and I did already address this by my comment on the non availability of real, linear voltage controlled resisters. I stated that in principle, one might be able to find a device that was strictly linear in order to achieve modulation. I also stated that such devices do not appear to exist, such that in practise, one generally has to use a non-linear device to achieve multiplication. It should go without comment that when one analyses the simple transistor multiplier that one only selects the first order linear term, and that this is term that generates the multiplication. This is trivially obvious, and was what I showed in my original analysis, gm is inherently a small signal property. Indeed, as this is only valid for small signals, more complex multipliers log the input signal so that in conjunction with the exponential relation results in perfect multiplication at all signal levels, originally due to Gilbert I might add. This confusion here appears to me to be one of semantics or x-wires, as is often the case on strongly held, but oppositely apposed views. gwhite claims that you don't inherently require a non-linear device to achieve multiplication, I claim that all practical devices have a non-linear transfer function, and it is this transfer function that results in multiplication. I don't believe we are arguing about the same point. I have nothing more to say on this. I have better things to do. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
gwhite wrote:
Frank Raffaeli wrote: gwhite wrote in message ... [snipped long diatribes] Dude, you are responding to one of the shorter messages. Class A works just fine in multipliers/modulators -- "non-linearity" of circuit elements is not required. Maybe you can analyze the old MC1496. That would be enlightening to you. But more important and more simple (it will save you loads of time), just apply *the* linearity test [snip] Hmmm .... you may be mistaking the (sometimes linear) current steering effect for the mechanism within the transistor that makes current steering possible: the relationship between gm and Ic ... or from another POV, the change in rbb with respect to bias current. These effects are non-linear. Non-linearity is *not* required to create DSB-AM out of transconductance type multipliers like the gilbert cell. In fact, *non-linearity is specifically something that designers hope to minimize* -- just like in any linear device. The standard linear approximation practice ensues: that is, the taylor expansion of exp(x) is done and the linear term is the desired one and *it is all that is required or wanted for this linear multiplier*. Ahh... now I see where the confusion is, and I did already address this by my comment on the non availability of real, linear voltage controlled resisters. I stated that in principle, one might be able to find a device that was strictly linear in order to achieve modulation. I also stated that such devices do not appear to exist, such that in practise, one generally has to use a non-linear device to achieve multiplication. It should go without comment that when one analyses the simple transistor multiplier that one only selects the first order linear term, and that this is term that generates the multiplication. This is trivially obvious, and was what I showed in my original analysis, gm is inherently a small signal property. Indeed, as this is only valid for small signals, more complex multipliers log the input signal so that in conjunction with the exponential relation results in perfect multiplication at all signal levels, originally due to Gilbert I might add. This confusion here appears to me to be one of semantics or x-wires, as is often the case on strongly held, but oppositely apposed views. gwhite claims that you don't inherently require a non-linear device to achieve multiplication, I claim that all practical devices have a non-linear transfer function, and it is this transfer function that results in multiplication. I don't believe we are arguing about the same point. I have nothing more to say on this. I have better things to do. Kevin Aylward http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. |
Kevin Aylward wrote:
gwhite wrote: The simple fact is you are wrong in thinking you can all of the sudden make up your own definition of linearity, or carry forward without challenge the mistaken definition of others. Absolute crap. Show me one respectable math reference that says if y=exp(x), that y is a linear function of x. You were right about one Show me one real practical example that does not use a device with a functional relation between input and output voltage/current that is linear, as I defined above. As did note as an after thought, it may be possible in principle, for example, maybe one could construct a true, linear with voltage, voltage controlled resistor. However, I am not aware of such magic devices. The physical reality is that it is not possible. Produce one and I will retract my claim. A light dependant resistor. One input drives a LED via a linearizer to compensate for LDR non-linearity. The LDR resistance is unaffected by the voltage across it. Therefore, the resulting current Io=f(V1,V2)= k.V1*V2 (4-quadrant multiplier or compensated gilbert cell) The circuit output is *superposition linear* relative to each input. dIo/dV1=k.V2, dIo/dV2=k.V1 (partial derivatives). In mixer operation, Io=f(Vin,Vosc). Vosc is an independant time-varying signal. Therefore, Io=f(Vin,Vosc(t)) or Io(t)=g(Vin,t). Because Io vs Vin is linear (4-quad multiplier), then dIo/dVin= g'(t) ie: a function of time only. This is the definition of a linear time-varying circuit. that is incorrect. You confuse the time-invariance property with the linearity property. You believe LTI systems are the *only* linear systems -- they are not according to the widely accepted and published definition of linearity. No. Linearity is widely understood to have many definitions. I have explained some of these already. An ideal multiplier is considered nonlinear with respect to a certain signal if a component of that signal is applied to *both* inputs simultaneously. Then: Io=k.(V1+a.V2)(a.V1+V2)= k.( aV1^2 + a.V2^2 + (1+a^2).V1.V2 ) |
Kevin Aylward wrote:
gwhite wrote: The simple fact is you are wrong in thinking you can all of the sudden make up your own definition of linearity, or carry forward without challenge the mistaken definition of others. Absolute crap. Show me one respectable math reference that says if y=exp(x), that y is a linear function of x. You were right about one Show me one real practical example that does not use a device with a functional relation between input and output voltage/current that is linear, as I defined above. As did note as an after thought, it may be possible in principle, for example, maybe one could construct a true, linear with voltage, voltage controlled resistor. However, I am not aware of such magic devices. The physical reality is that it is not possible. Produce one and I will retract my claim. A light dependant resistor. One input drives a LED via a linearizer to compensate for LDR non-linearity. The LDR resistance is unaffected by the voltage across it. Therefore, the resulting current Io=f(V1,V2)= k.V1*V2 (4-quadrant multiplier or compensated gilbert cell) The circuit output is *superposition linear* relative to each input. dIo/dV1=k.V2, dIo/dV2=k.V1 (partial derivatives). In mixer operation, Io=f(Vin,Vosc). Vosc is an independant time-varying signal. Therefore, Io=f(Vin,Vosc(t)) or Io(t)=g(Vin,t). Because Io vs Vin is linear (4-quad multiplier), then dIo/dVin= g'(t) ie: a function of time only. This is the definition of a linear time-varying circuit. that is incorrect. You confuse the time-invariance property with the linearity property. You believe LTI systems are the *only* linear systems -- they are not according to the widely accepted and published definition of linearity. No. Linearity is widely understood to have many definitions. I have explained some of these already. An ideal multiplier is considered nonlinear with respect to a certain signal if a component of that signal is applied to *both* inputs simultaneously. Then: Io=k.(V1+a.V2)(a.V1+V2)= k.( aV1^2 + a.V2^2 + (1+a^2).V1.V2 ) |
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