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StackExchange through my eyes

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Over the years of contributing to StackExchange Electrical Engineering (SE EE) I have accumulated quite a few observations that I decided to share in this post. In this way, I want to give some, albeit refracted through my vision, information to newcomers. First impressions My involvement with StackExchange began in late 2014 with enthusiasm as usual. But I was a bit taken aback by the rough treatment there and after three months I stopped participating. I returned again after five years of collaborating in the more academic but sterile environment of ResearchGate... and I have stayed here ever since. StackExchange was the first time I encountered such a strange question-and-answer platform. To me (only) asking and answering questions is a too limited form of communication between human beings. Indeed, it is a very essential part of this process, but it cannot be reduced to this alone. And in SE EE any other form is suppressed. I still cannot figure out why the discussion is ba
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StackExchange през моя поглед

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През годините на сътрудничество в StackExchange Electrical Engineering (SE EE) натрупах доста наблюдения, които реших да споделя в този пост. С това искам да дам някаква, макар и пречупена през моето виждане информация на новодошлите. Първи впечатления Моето участие в StackExchange започна в края на 2014 г. с ентусиазъм, както обикновено. Но аз бях малко стъписан от грубите отношения там и след три месеца прекратих участието си.  Завърнах се отново след пет години, през време на които сътрудничих в по-академичната, но пък стерилна среда на ResearchGate... и останах тук досега. В StackExchange за първи път се срещнах с такава странна "въпрос-отговор" платформа. За мен (само) задаването на въпроси и отговарянето им е една ограничена форма на общуване между човешки същества. Действително, то е много съществена част от този процес, но той не може да бъде сведен само до това. А в SE EE се потиска всякаква друга форма. И досега не мога да разбера защо дискусията е забранена; та на
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How to bias a common-source amplifier with a current-source load?

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This is  my answer  to the  SE EE question  about the famous 'dynamic load'.  -------------------- Basic idea It is quite paradoxical because in this arrangement, two current sources are connected in series. According to the laws of electrical circuits, this is incorrect because even with a minimal difference in their currents, each of them will struggle to establish its current in the circuit. As a result of this "tug of war", the voltage at their midpoint will increase in the corresponding direction to infinity. But this "negative" phenomenon is used in modern integrated circuits to obtain something very useful - extremely high gain . Implementation How to set Vin? Here are three techniques for this purpose: Simply set Vin by its parameters window in the simulator Use the FET transfer characteristic Introduce negative feedback and calculate Vin needed from the resistor ratio For the purposes of my intuitive explanation, I will use the first option. To show
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How does the current and voltage stabilize in a differential amplifier?

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This is my answer to the  SE EE question  about the famous "long-tailed pair". -------------------- Basic idea It can be revealed at а functional level by equivalent electrical circuits. In this brilliant circuit solution initially called with the figurative name "long-tailed pair", a total of three sources - two voltage and one current - interact like living beings. In some cases they help each other and in others they oppose each other like people in the game tug of war . Implementation The two voltage sources are implemented by the source followers Q1 and Q2. The current source (or, more precisely speaking, current sink ) is implemented by another transistor (not shown in the OP's circuit). So these sources are not actually true sources (producing power) but dynamic resistors that only regulate voltage and current (see more about this approach in another related question and answer  of mine). Conceptual circuit To simulate the circuit, actually we have to
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Creating a circuit with negative differential resistance

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This is my  answer  to this  SE EE question .  Here I have tried to show the similarities and differences between the two types of negative resistance - differential and absolute. -------------------- Why does voltage decrease when current increases? The OP said: "By negative differential resistance, I mean a circuit where the current decreases when the voltage increases." Well, true... But what is the physical meaning of this statement? How does this magic work? Is it something useful and therefore desirable? If so, what can we use it for? Let's understand it thinking as humans and explain it without using meaningless verbal clichés. Basic idea The purpose of a negative resistor is to do the opposite of what a "positive" resistor does, i.e. to add rather than dissipate power. True negative resistors do this by adding voltage in series or current in parallel from their own built-in sources. But how is the humble resistor to do so when it does not have that? The
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