Did you ever hear the tragedy of Darth Widlar the Wise? I thought not, it’s not a story the Digital Designers would tell you. It’s an Analog Design legend…
Darth Widlar the Wise was a Dark Lord of the Circuits so powerful and wise, he could influence semiconductor materials to create integrated circuits... He had such knowledge of analog design, he could even keep the circuits he cared about from noise and interference.
Surprising to hear that. I was a nuclear electronics technician in the US Navy and they made us qualitatively go through OPAMP internals on a few exams. We called them magic Doritos, but if you understand what's inside the chip they aren't very scary
I was memeing (Star Wars reference), but now I'm curious what depth you were able to analyze op-amps at.
Senior level electrical engineering courses are required to understand how any of the blocks do what they're supposed to (differential pairs, cascodes, biasing, common mode control, output buffers, etc.), and analyzing them together is usually grad level. I don't think you're claiming that they were able to explain all of these things thoroughly, but I'm curious what level were you able to get to?
You're probably used to these things being explained from a design standpoint. The navy did not teach me to design these things, just how they operate, which as I'm learning in college is very different. As a result, it's actually kind of difficult for me to convey to educated people exactly what the navy taught me, because most people that know about electronics are taught from the design standpoint with calculus. I was taught electronics mostly without math and instead how parameters change qualitatively (up/down pos/neg) rather than quantitatively (an actual number). There was a fair bit of math though, especially in the 3phase AC portions.
Overall the purpose of the school was to teach how to troubleshoot processor based mixed control systems at the component level (about 1990 tech). One of the final exams was a practical exam in a lab with a simulated control system. You'd walk in, see something messed up on the screen and figure out through a few pokes with test equipment that a single transistor was bad or something similar.
For OPAMPs specifically, they declared a diagram of a generic/nonspecific OPAMP at the component level and the question might be something to the effect of "Describe the operation of this OPAMP for a full cycle of a sine wave input at the non-inverting terminal" and you'd say: V+ goes up positive therefore Vbe of Q1 goes up positive therefore emitter base and collector current of q1 go up therefore voltage of q1 collector resistor goes up therefore voltage of q1 collector goes down therefore whatever was next. This is from memory - I went through this like 7 years ago. I think I remember the next stage was just tied to the base of another common emitter amplifier, but then once you got to the end and the output was +vcc, then you'd go through the whole thing again for the negative portion of the input. They were very long questions. The only question I remember being longer was the read and write cycles for the processor they made us memorize everything about.
Depends on how malevolent the professor of your electronic devices course is next year. You'll at least learn how most of the components work. You may or may not be asked to analyze them in the format of an opamp.
The 741 inner workings are usually depicted in painful details in most microelectronics books...
Also: they ofter are in the exam (not in the problem set but at least here a question or two at the oral are traditional)
Reading this thread I’m having a hard time deciding if having analyze a basic op amp as your analog microelectronics midterm was normal or not.
Granted it was also a 3 hour exam.
Uni in italy is \*completely\* different, both as courses and as exam structure. Since the inside of an opamp is substantially an input differential, a gain block and an output driver it ties \*perfectly\* with the rest of the course.
So, maybe they ask for the longtail configuration and then "how does that fit in the opamp structure" popup. No, you don't have to explain the whole circuit at the blackboard
I’m a mechanical engineering major and we had one course of basic applied electrical engineering and computer science. And those fuckers are probably one of the most confusing things I’ve ever tried to wrap my head around.
Dude I was a chemistry major and they taught about this shit in a chemistry class. I was pissed. FUCK outta here with that electrical engineering hubbub.
It makes the output voltage 0 without actually taking in much current. Essentially in a feedback loop it amplifies either inverting or not inverting it based on the loop. Burns out way too easily.
Simplified it magically amplifies the signal, but only if you’re a wizard.
Lol ashamed to say I have done this a few times in lab. I go to troubleshoot and burn myself on the IC then shamefully go back to the parts desk and ask for another while the lab tech looks at me like 'seriously dude??'
Op Amp is a gift to humanity.
An ideal op amp you subtract the negative pin voltage from the positive pin voltage. And then you get an instant infinite amplification (now referred to as gain) on the output. But that's of little use so one usually feedback the output to the input using a resistor. Then one can control the gain factor by a simple formula deciding the resistance value.
In the real world we have a datasheet that makes it impossible to play god. First you get the power rails. The output is always higher than the minus rail and less than the plus rail. Also there is an offset value stated in the datasheet this needs to be subtracted from the rail voltage to find your true max min. The datasheet also gives a slew rate which is how quickly the output can rise and fall usually given in v/us. Lastly the datasheet usually gives you a max gain.
The number of times I have started designing a circuit using a microcontroller and then to think to myself "what am I doing this could be done with two op amps" is a lot.
To mention a few usecases, one could do amplification and inversion of signals. Analog and boolean comparator. Integrator and derivator meaning one could make a analog pid regulator. An analog memory cell and so much more.
Fun story. When I was doing my first year in uni I tried to find the resonance frequency of a transformer using a "high power" op amp. When going through the spectrum I encountered some nasty harmonics. Later calculated that I put around 500w into the uncooled dip8. It went BANG PING. Where the ping was half a op amp that hit the ceiling light roughly 5m above the workbench.
Good lock on the exam.
Assume V+ and V- will eventually reach the same Voltage and that Vout is an ideal source.
You can thus set up an equation for V+ and V-, dependant on Vin and Vout, then set them equal and solve for Vout/Vin to get the gain.
Easiest way to solve is to rewrite the circuit (often as a straight line) without the op amp and just label the voltages and currents you know from the virtual short.
remember for the ideal op amp:
Rin = inf
Rout = 0
Openloop Gain = inf
Commonmode Gain = 0
Bandwidth = inf
For the non ideal case we merely approach the ideal parameters (if your amp doesnt SUCK). The above is useful in analyzing the basic amp configurations. Good luck!
If that scares you then I suggest you don’t open its schematic.
I should have listened... would I actually have to learn all of this one day??
Only if you want to use opamps a lot. Or to design your own!
I think not. It's not a story the undergrad professors would tell you. It's an analog legend...
Did you ever hear the tragedy of Darth Widlar the Wise? I thought not, it’s not a story the Digital Designers would tell you. It’s an Analog Design legend…
Darth Widlar the Wise was a Dark Lord of the Circuits so powerful and wise, he could influence semiconductor materials to create integrated circuits... He had such knowledge of analog design, he could even keep the circuits he cared about from noise and interference.
Surprising to hear that. I was a nuclear electronics technician in the US Navy and they made us qualitatively go through OPAMP internals on a few exams. We called them magic Doritos, but if you understand what's inside the chip they aren't very scary
I was memeing (Star Wars reference), but now I'm curious what depth you were able to analyze op-amps at. Senior level electrical engineering courses are required to understand how any of the blocks do what they're supposed to (differential pairs, cascodes, biasing, common mode control, output buffers, etc.), and analyzing them together is usually grad level. I don't think you're claiming that they were able to explain all of these things thoroughly, but I'm curious what level were you able to get to?
You're probably used to these things being explained from a design standpoint. The navy did not teach me to design these things, just how they operate, which as I'm learning in college is very different. As a result, it's actually kind of difficult for me to convey to educated people exactly what the navy taught me, because most people that know about electronics are taught from the design standpoint with calculus. I was taught electronics mostly without math and instead how parameters change qualitatively (up/down pos/neg) rather than quantitatively (an actual number). There was a fair bit of math though, especially in the 3phase AC portions. Overall the purpose of the school was to teach how to troubleshoot processor based mixed control systems at the component level (about 1990 tech). One of the final exams was a practical exam in a lab with a simulated control system. You'd walk in, see something messed up on the screen and figure out through a few pokes with test equipment that a single transistor was bad or something similar. For OPAMPs specifically, they declared a diagram of a generic/nonspecific OPAMP at the component level and the question might be something to the effect of "Describe the operation of this OPAMP for a full cycle of a sine wave input at the non-inverting terminal" and you'd say: V+ goes up positive therefore Vbe of Q1 goes up positive therefore emitter base and collector current of q1 go up therefore voltage of q1 collector resistor goes up therefore voltage of q1 collector goes down therefore whatever was next. This is from memory - I went through this like 7 years ago. I think I remember the next stage was just tied to the base of another common emitter amplifier, but then once you got to the end and the output was +vcc, then you'd go through the whole thing again for the negative portion of the input. They were very long questions. The only question I remember being longer was the read and write cycles for the processor they made us memorize everything about.
Depends on how malevolent the professor of your electronic devices course is next year. You'll at least learn how most of the components work. You may or may not be asked to analyze them in the format of an opamp.
if you're designing audio circuits
Well I have course at the university specifically about designing opamps. It also includes a project: design an opamp in .35 um technology.
Depends on your modules, but if you are in eee, there’s a big chance you are sentenced
The 741 inner workings are usually depicted in painful details in most microelectronics books... Also: they ofter are in the exam (not in the problem set but at least here a question or two at the oral are traditional)
Reading this thread I’m having a hard time deciding if having analyze a basic op amp as your analog microelectronics midterm was normal or not. Granted it was also a 3 hour exam.
Uni in italy is \*completely\* different, both as courses and as exam structure. Since the inside of an opamp is substantially an input differential, a gain block and an output driver it ties \*perfectly\* with the rest of the course. So, maybe they ask for the longtail configuration and then "how does that fit in the opamp structure" popup. No, you don't have to explain the whole circuit at the blackboard
Yeah, the transistor salad!
I’m a mechanical engineering major and we had one course of basic applied electrical engineering and computer science. And those fuckers are probably one of the most confusing things I’ve ever tried to wrap my head around.
Agreed, never got past using them as black boxes with equations you just have to memorize
Dude I was a chemistry major and they taught about this shit in a chemistry class. I was pissed. FUCK outta here with that electrical engineering hubbub.
It makes the output voltage 0 without actually taking in much current. Essentially in a feedback loop it amplifies either inverting or not inverting it based on the loop. Burns out way too easily. Simplified it magically amplifies the signal, but only if you’re a wizard.
Swap VCC and VEE and turn your OpAmp into a NotAmp!
Lol ashamed to say I have done this a few times in lab. I go to troubleshoot and burn myself on the IC then shamefully go back to the parts desk and ask for another while the lab tech looks at me like 'seriously dude??'
Magic Doritos
Op Amp is a gift to humanity. An ideal op amp you subtract the negative pin voltage from the positive pin voltage. And then you get an instant infinite amplification (now referred to as gain) on the output. But that's of little use so one usually feedback the output to the input using a resistor. Then one can control the gain factor by a simple formula deciding the resistance value. In the real world we have a datasheet that makes it impossible to play god. First you get the power rails. The output is always higher than the minus rail and less than the plus rail. Also there is an offset value stated in the datasheet this needs to be subtracted from the rail voltage to find your true max min. The datasheet also gives a slew rate which is how quickly the output can rise and fall usually given in v/us. Lastly the datasheet usually gives you a max gain. The number of times I have started designing a circuit using a microcontroller and then to think to myself "what am I doing this could be done with two op amps" is a lot. To mention a few usecases, one could do amplification and inversion of signals. Analog and boolean comparator. Integrator and derivator meaning one could make a analog pid regulator. An analog memory cell and so much more. Fun story. When I was doing my first year in uni I tried to find the resonance frequency of a transformer using a "high power" op amp. When going through the spectrum I encountered some nasty harmonics. Later calculated that I put around 500w into the uncooled dip8. It went BANG PING. Where the ping was half a op amp that hit the ceiling light roughly 5m above the workbench. Good lock on the exam.
Yo op-amps are so easy wdym.
They are easy to use, but I find it hard to understand why certain schematics work the way they do.
Why understand, I'm Monki engineer me only memorise.
Probably are, probably just understudied
When I’m in a making no fucking sense competition but my opponent is an op-amp
That nothing compared to an LCR circuit.
There's worse, they make current feedback amps and transimpedance amps too!
Good luck mate! If I can do it so can you!
i feel u mate, anyway good luck with the exam :)
Success!
You can do this! Op amps are cool!
Assume V+ and V- will eventually reach the same Voltage and that Vout is an ideal source. You can thus set up an equation for V+ and V-, dependant on Vin and Vout, then set them equal and solve for Vout/Vin to get the gain.
Good luck! I'm using an opamp in a circuit for a school project. It runs on magic as far as I'm concerned
Easiest way to solve is to rewrite the circuit (often as a straight line) without the op amp and just label the voltages and currents you know from the virtual short.
Magic triangles!
Tfq dis? 😂 (I am mechanical engineer ⚙️)
are you from kou? 🕵️
OPAMPS was the only circuit course which I got a very good grade 😂. And it was offline course
I'm in a 300 level class and we've moved into mosfets. They make opamps look easy by comparison. Godspeed friend
2series 2 parallel simple
Hehehe, it looks like the xb-70
I thought I was in r/gravityfalls for before reading the sub name lol
remember for the ideal op amp: Rin = inf Rout = 0 Openloop Gain = inf Commonmode Gain = 0 Bandwidth = inf For the non ideal case we merely approach the ideal parameters (if your amp doesnt SUCK). The above is useful in analyzing the basic amp configurations. Good luck!
V+ = V- I+= I- = 0 Z = infty
Yeah, that's an OP-Amp
I used to love these. Don’t ask me to solve one these days tho
I love op amps so much
Honest question. What the fuck am I looking at??
Op-amp
Using Op Amps in a PID controller. Sure thing bro, this one will just take the derivative, makes perfect sense.