For an inverting opamp, is inverting the same thing as an 180 degree phase shift?












3












$begingroup$


Many texts talk about 180 degree phase shift as a function of the inverting opamp.



Is that correct? It seems to me inverting is happening almost immediately but phase is related to time and period and time delay between the input and output.










share|improve this question











$endgroup$












  • $begingroup$
    Phase is making sense for periodical sinusoidal signals, where phase shift of 180 degrees is equivalent to multiplication by -1. For other signals it is not the same.
    $endgroup$
    – Eugene Sh.
    6 hours ago








  • 1




    $begingroup$
    But thats an illusion for the sine case, it just “looks like” phase shifted. Correct?
    $endgroup$
    – Genzo
    6 hours ago












  • $begingroup$
    Yes it is an "illusion" but if it is a pure sinewave, you will be unable to tell the difference so it does not matter, the resulting signal is the same whether you invert of phase-delay.
    $endgroup$
    – Bimpelrekkie
    6 hours ago
















3












$begingroup$


Many texts talk about 180 degree phase shift as a function of the inverting opamp.



Is that correct? It seems to me inverting is happening almost immediately but phase is related to time and period and time delay between the input and output.










share|improve this question











$endgroup$












  • $begingroup$
    Phase is making sense for periodical sinusoidal signals, where phase shift of 180 degrees is equivalent to multiplication by -1. For other signals it is not the same.
    $endgroup$
    – Eugene Sh.
    6 hours ago








  • 1




    $begingroup$
    But thats an illusion for the sine case, it just “looks like” phase shifted. Correct?
    $endgroup$
    – Genzo
    6 hours ago












  • $begingroup$
    Yes it is an "illusion" but if it is a pure sinewave, you will be unable to tell the difference so it does not matter, the resulting signal is the same whether you invert of phase-delay.
    $endgroup$
    – Bimpelrekkie
    6 hours ago














3












3








3





$begingroup$


Many texts talk about 180 degree phase shift as a function of the inverting opamp.



Is that correct? It seems to me inverting is happening almost immediately but phase is related to time and period and time delay between the input and output.










share|improve this question











$endgroup$




Many texts talk about 180 degree phase shift as a function of the inverting opamp.



Is that correct? It seems to me inverting is happening almost immediately but phase is related to time and period and time delay between the input and output.







op-amp






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 35 mins ago









Acccumulation

1133




1133










asked 6 hours ago









GenzoGenzo

366217




366217












  • $begingroup$
    Phase is making sense for periodical sinusoidal signals, where phase shift of 180 degrees is equivalent to multiplication by -1. For other signals it is not the same.
    $endgroup$
    – Eugene Sh.
    6 hours ago








  • 1




    $begingroup$
    But thats an illusion for the sine case, it just “looks like” phase shifted. Correct?
    $endgroup$
    – Genzo
    6 hours ago












  • $begingroup$
    Yes it is an "illusion" but if it is a pure sinewave, you will be unable to tell the difference so it does not matter, the resulting signal is the same whether you invert of phase-delay.
    $endgroup$
    – Bimpelrekkie
    6 hours ago


















  • $begingroup$
    Phase is making sense for periodical sinusoidal signals, where phase shift of 180 degrees is equivalent to multiplication by -1. For other signals it is not the same.
    $endgroup$
    – Eugene Sh.
    6 hours ago








  • 1




    $begingroup$
    But thats an illusion for the sine case, it just “looks like” phase shifted. Correct?
    $endgroup$
    – Genzo
    6 hours ago












  • $begingroup$
    Yes it is an "illusion" but if it is a pure sinewave, you will be unable to tell the difference so it does not matter, the resulting signal is the same whether you invert of phase-delay.
    $endgroup$
    – Bimpelrekkie
    6 hours ago
















$begingroup$
Phase is making sense for periodical sinusoidal signals, where phase shift of 180 degrees is equivalent to multiplication by -1. For other signals it is not the same.
$endgroup$
– Eugene Sh.
6 hours ago






$begingroup$
Phase is making sense for periodical sinusoidal signals, where phase shift of 180 degrees is equivalent to multiplication by -1. For other signals it is not the same.
$endgroup$
– Eugene Sh.
6 hours ago






1




1




$begingroup$
But thats an illusion for the sine case, it just “looks like” phase shifted. Correct?
$endgroup$
– Genzo
6 hours ago






$begingroup$
But thats an illusion for the sine case, it just “looks like” phase shifted. Correct?
$endgroup$
– Genzo
6 hours ago














$begingroup$
Yes it is an "illusion" but if it is a pure sinewave, you will be unable to tell the difference so it does not matter, the resulting signal is the same whether you invert of phase-delay.
$endgroup$
– Bimpelrekkie
6 hours ago




$begingroup$
Yes it is an "illusion" but if it is a pure sinewave, you will be unable to tell the difference so it does not matter, the resulting signal is the same whether you invert of phase-delay.
$endgroup$
– Bimpelrekkie
6 hours ago










2 Answers
2






active

oldest

votes


















6












$begingroup$

An inverting op-amp inverts the signal; it does not phase change the signal at the output by 180 degrees although, if the input waveform were a sinewave, then it would look like 180 degrees of phase shift.






share|improve this answer









$endgroup$













  • $begingroup$
    So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
    $endgroup$
    – Genzo
    6 hours ago










  • $begingroup$
    @Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
    $endgroup$
    – Andy aka
    6 hours ago






  • 1




    $begingroup$
    More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
    $endgroup$
    – Evan
    6 hours ago












  • $begingroup$
    Filters have phase shift and group delay. Inverters have 180 deg inversion
    $endgroup$
    – Sunnyskyguy EE75
    5 hours ago










  • $begingroup$
    Another situation where it matters is if the voltage and current are out of phase.
    $endgroup$
    – Acccumulation
    4 hours ago



















2












$begingroup$

How an opamp behaves depends on how you configure it in a circuit.



But the opamp is actually irrelevant to your actual question.



I think that your actual question is:



Is inverting a signal the same as phase shifting it by 180 degrees



What we mean by inverting a signal is multiplying the signal by -1, so +33mV becomes -33 mV
and -0.5 V becomes +0.5 V.



A 180 degree phase shift is indeed related to time but since phase is also coupled to frequency we only tend to use phase when talking about a single frequency. The only signal that contains a single frequency is a sinewave. Now for a sinewave inverting it (multiply it by -1) or phase shifting it 180 degrees will result in the same signal.



So yes, for sinusoidal signals, inverting and phase shifting with 180 degrees is the same thing.



Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing. Then the phase is only related to the base (lowest) frequency.



For non-periodic signals (these do not have a base-frequency) this isn't the case.






share|improve this answer











$endgroup$













  • $begingroup$
    "Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
    $endgroup$
    – Acccumulation
    4 hours ago











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









6












$begingroup$

An inverting op-amp inverts the signal; it does not phase change the signal at the output by 180 degrees although, if the input waveform were a sinewave, then it would look like 180 degrees of phase shift.






share|improve this answer









$endgroup$













  • $begingroup$
    So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
    $endgroup$
    – Genzo
    6 hours ago










  • $begingroup$
    @Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
    $endgroup$
    – Andy aka
    6 hours ago






  • 1




    $begingroup$
    More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
    $endgroup$
    – Evan
    6 hours ago












  • $begingroup$
    Filters have phase shift and group delay. Inverters have 180 deg inversion
    $endgroup$
    – Sunnyskyguy EE75
    5 hours ago










  • $begingroup$
    Another situation where it matters is if the voltage and current are out of phase.
    $endgroup$
    – Acccumulation
    4 hours ago
















6












$begingroup$

An inverting op-amp inverts the signal; it does not phase change the signal at the output by 180 degrees although, if the input waveform were a sinewave, then it would look like 180 degrees of phase shift.






share|improve this answer









$endgroup$













  • $begingroup$
    So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
    $endgroup$
    – Genzo
    6 hours ago










  • $begingroup$
    @Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
    $endgroup$
    – Andy aka
    6 hours ago






  • 1




    $begingroup$
    More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
    $endgroup$
    – Evan
    6 hours ago












  • $begingroup$
    Filters have phase shift and group delay. Inverters have 180 deg inversion
    $endgroup$
    – Sunnyskyguy EE75
    5 hours ago










  • $begingroup$
    Another situation where it matters is if the voltage and current are out of phase.
    $endgroup$
    – Acccumulation
    4 hours ago














6












6








6





$begingroup$

An inverting op-amp inverts the signal; it does not phase change the signal at the output by 180 degrees although, if the input waveform were a sinewave, then it would look like 180 degrees of phase shift.






share|improve this answer









$endgroup$



An inverting op-amp inverts the signal; it does not phase change the signal at the output by 180 degrees although, if the input waveform were a sinewave, then it would look like 180 degrees of phase shift.







share|improve this answer












share|improve this answer



share|improve this answer










answered 6 hours ago









Andy akaAndy aka

240k11178411




240k11178411












  • $begingroup$
    So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
    $endgroup$
    – Genzo
    6 hours ago










  • $begingroup$
    @Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
    $endgroup$
    – Andy aka
    6 hours ago






  • 1




    $begingroup$
    More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
    $endgroup$
    – Evan
    6 hours ago












  • $begingroup$
    Filters have phase shift and group delay. Inverters have 180 deg inversion
    $endgroup$
    – Sunnyskyguy EE75
    5 hours ago










  • $begingroup$
    Another situation where it matters is if the voltage and current are out of phase.
    $endgroup$
    – Acccumulation
    4 hours ago


















  • $begingroup$
    So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
    $endgroup$
    – Genzo
    6 hours ago










  • $begingroup$
    @Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
    $endgroup$
    – Andy aka
    6 hours ago






  • 1




    $begingroup$
    More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
    $endgroup$
    – Evan
    6 hours ago












  • $begingroup$
    Filters have phase shift and group delay. Inverters have 180 deg inversion
    $endgroup$
    – Sunnyskyguy EE75
    5 hours ago










  • $begingroup$
    Another situation where it matters is if the voltage and current are out of phase.
    $endgroup$
    – Acccumulation
    4 hours ago
















$begingroup$
So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
$endgroup$
– Genzo
6 hours ago




$begingroup$
So it “looks like” as if it is phase shifted but actually it is not. There is a nuance here.
$endgroup$
– Genzo
6 hours ago












$begingroup$
@Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
$endgroup$
– Andy aka
6 hours ago




$begingroup$
@Genzo indeed and a lot of EEs will use the terms interchangeably (including me but I always try and correct these bad habits of mine).
$endgroup$
– Andy aka
6 hours ago




1




1




$begingroup$
More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
$endgroup$
– Evan
6 hours ago






$begingroup$
More specifically inverting is equivalent to phase shifting every constituent sine wave in the Fourier representation of the signal by 180 degrees. So in that sense it is equivalent, but potentially miselading in cases where there are other "phases" of interest, such as modulated signals where "invert" is not necessarily the same as phase shifting the modulation by 180 degrees. This is where people get tripped up, phase actually means slightly different things in different contexts.
$endgroup$
– Evan
6 hours ago














$begingroup$
Filters have phase shift and group delay. Inverters have 180 deg inversion
$endgroup$
– Sunnyskyguy EE75
5 hours ago




$begingroup$
Filters have phase shift and group delay. Inverters have 180 deg inversion
$endgroup$
– Sunnyskyguy EE75
5 hours ago












$begingroup$
Another situation where it matters is if the voltage and current are out of phase.
$endgroup$
– Acccumulation
4 hours ago




$begingroup$
Another situation where it matters is if the voltage and current are out of phase.
$endgroup$
– Acccumulation
4 hours ago













2












$begingroup$

How an opamp behaves depends on how you configure it in a circuit.



But the opamp is actually irrelevant to your actual question.



I think that your actual question is:



Is inverting a signal the same as phase shifting it by 180 degrees



What we mean by inverting a signal is multiplying the signal by -1, so +33mV becomes -33 mV
and -0.5 V becomes +0.5 V.



A 180 degree phase shift is indeed related to time but since phase is also coupled to frequency we only tend to use phase when talking about a single frequency. The only signal that contains a single frequency is a sinewave. Now for a sinewave inverting it (multiply it by -1) or phase shifting it 180 degrees will result in the same signal.



So yes, for sinusoidal signals, inverting and phase shifting with 180 degrees is the same thing.



Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing. Then the phase is only related to the base (lowest) frequency.



For non-periodic signals (these do not have a base-frequency) this isn't the case.






share|improve this answer











$endgroup$













  • $begingroup$
    "Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
    $endgroup$
    – Acccumulation
    4 hours ago
















2












$begingroup$

How an opamp behaves depends on how you configure it in a circuit.



But the opamp is actually irrelevant to your actual question.



I think that your actual question is:



Is inverting a signal the same as phase shifting it by 180 degrees



What we mean by inverting a signal is multiplying the signal by -1, so +33mV becomes -33 mV
and -0.5 V becomes +0.5 V.



A 180 degree phase shift is indeed related to time but since phase is also coupled to frequency we only tend to use phase when talking about a single frequency. The only signal that contains a single frequency is a sinewave. Now for a sinewave inverting it (multiply it by -1) or phase shifting it 180 degrees will result in the same signal.



So yes, for sinusoidal signals, inverting and phase shifting with 180 degrees is the same thing.



Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing. Then the phase is only related to the base (lowest) frequency.



For non-periodic signals (these do not have a base-frequency) this isn't the case.






share|improve this answer











$endgroup$













  • $begingroup$
    "Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
    $endgroup$
    – Acccumulation
    4 hours ago














2












2








2





$begingroup$

How an opamp behaves depends on how you configure it in a circuit.



But the opamp is actually irrelevant to your actual question.



I think that your actual question is:



Is inverting a signal the same as phase shifting it by 180 degrees



What we mean by inverting a signal is multiplying the signal by -1, so +33mV becomes -33 mV
and -0.5 V becomes +0.5 V.



A 180 degree phase shift is indeed related to time but since phase is also coupled to frequency we only tend to use phase when talking about a single frequency. The only signal that contains a single frequency is a sinewave. Now for a sinewave inverting it (multiply it by -1) or phase shifting it 180 degrees will result in the same signal.



So yes, for sinusoidal signals, inverting and phase shifting with 180 degrees is the same thing.



Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing. Then the phase is only related to the base (lowest) frequency.



For non-periodic signals (these do not have a base-frequency) this isn't the case.






share|improve this answer











$endgroup$



How an opamp behaves depends on how you configure it in a circuit.



But the opamp is actually irrelevant to your actual question.



I think that your actual question is:



Is inverting a signal the same as phase shifting it by 180 degrees



What we mean by inverting a signal is multiplying the signal by -1, so +33mV becomes -33 mV
and -0.5 V becomes +0.5 V.



A 180 degree phase shift is indeed related to time but since phase is also coupled to frequency we only tend to use phase when talking about a single frequency. The only signal that contains a single frequency is a sinewave. Now for a sinewave inverting it (multiply it by -1) or phase shifting it 180 degrees will result in the same signal.



So yes, for sinusoidal signals, inverting and phase shifting with 180 degrees is the same thing.



Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing. Then the phase is only related to the base (lowest) frequency.



For non-periodic signals (these do not have a base-frequency) this isn't the case.







share|improve this answer














share|improve this answer



share|improve this answer








edited 6 hours ago

























answered 6 hours ago









BimpelrekkieBimpelrekkie

47.9k240105




47.9k240105












  • $begingroup$
    "Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
    $endgroup$
    – Acccumulation
    4 hours ago


















  • $begingroup$
    "Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
    $endgroup$
    – Acccumulation
    4 hours ago
















$begingroup$
"Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
$endgroup$
– Acccumulation
4 hours ago




$begingroup$
"Also for periodic signals like square waves and sawtooth signals, which consist of a base frequency and harmonics, inverting and phase shifting with 180 degrees is the same thing." That makes it sound like it's true of all periodic waves. It's only true of odd waves (i.e. nothing but odd harmonics).
$endgroup$
– Acccumulation
4 hours ago


















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