Hi,
I'm an electronic am amateurs. Recently, I have a paper work to make a complete paper about Non-inverting Amplifier.
I have read so many electric note about it, one of them is "When a positive phase is received, a positive phase is output, whereas the negative phase is output. The phases of non-inverting end and the output end are the same. In other words, the signal is applied to the non-inverting input of the op-amp, and it is not inverted at the output when compared to the input."(source: Non-Inverting and Inverting Amplifiers Basic Analysis), I think is simple but give no examples to explain clearly. So I want to get more idea about non-inverting amplifier from different aspects, wiki, electronic articles, electric forums, whatever...
Many thanks
Perreny
I'm an electronic am amateurs. Recently, I have a paper work to make a complete paper about Non-inverting Amplifier.
I have read so many electric note about it, one of them is "When a positive phase is received, a positive phase is output, whereas the negative phase is output. The phases of non-inverting end and the output end are the same. In other words, the signal is applied to the non-inverting input of the op-amp, and it is not inverted at the output when compared to the input."(source: Non-Inverting and Inverting Amplifiers Basic Analysis), I think is simple but give no examples to explain clearly. So I want to get more idea about non-inverting amplifier from different aspects, wiki, electronic articles, electric forums, whatever...
Many thanks
Perreny
A non-inverted phase output signal will have the exact shape of the original signal, but at a different scale (usually greater than 1:1). If the amplifier is unity-gain it will look exactly the same in all respects.
A phase-inverted signal will look similar to the original, but will be a mirror image around the Z axis. Segments of the original signal that are moving in a positive direction (slope) will be going in the opposite (negative) direction in the inverted signal.
These two signals are inversions of each other:
A phase-inverted signal will look similar to the original, but will be a mirror image around the Z axis. Segments of the original signal that are moving in a positive direction (slope) will be going in the opposite (negative) direction in the inverted signal.
These two signals are inversions of each other:
An externally hosted image should be here but it was not working when we last tested it.
In AM modulation, you can see both polarities on top and bottom of the HF-signal: on top is the non-inverted signal, and on the bottom the inverted signal.
Shaun showed this clearly, just imagine a hf carrier running between the two shown signals in the graph.
(funny signature Shaun, I can read it!)
Shaun showed this clearly, just imagine a hf carrier running between the two shown signals in the graph.
(funny signature Shaun, I can read it!)
It's less confusing to use the proper term "polarity" instead of "phase" which is a misnomer.
There is no phase shift involved. Think of reversing the connection of the secondary of a transformer.
The polarity of the output will reverse.
Same polarity output = non-inverting amplifier
Opposite polarity output = inverting amplifier
Op-Amp Basics
There is no phase shift involved. Think of reversing the connection of the secondary of a transformer.
The polarity of the output will reverse.
Same polarity output = non-inverting amplifier
Opposite polarity output = inverting amplifier
Op-Amp Basics
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This is not correct. Three inverting amplifiers connected in series simply invert the input polarity.
There is no phase shift involved, as can be seen by using a pulse (or other non-repetitive waveform),
instead of a sine wave, like this:
http://files.ctctcdn.com/3338493d001/30a287bd-6db6-4136-b63b-62c0274fbf94.jpg
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[QUOTE=Perreny;6231039]I have read so many electric note about it, one of them is "When a positive phase is received, a positive phase is output, whereas the negative phase is output. (source: [/QUOTE]
That page you are quoting is poorly written (google translated maybe?)
and the phrase I highlighted is plain WRONG. Meaningless.
No surprise it confuses you.
That page you are quoting is poorly written (google translated maybe?)
and the phrase I highlighted is plain WRONG. Meaningless.
No surprise it confuses you.
The definition of phase stems from the behaviour of periodic functions. Alternating voltages of sine waves, square waves and any repeating fixed pattern, produces a number of such patterns every second. When at the instant of turning on a signal, that is, time = 0 seconds, the pattern does not start at its very beginning, but at some other point, the phase is said to be bigger than zero. If for instance, the pattern starts at say, after 25% of its waveform, the phase is (25/100)*360 degrees = 90 degrees. If radians are used, this would be, (25/100)*2*π radians = π/2 radians.
The phase is simply the percentage multiplied by 360 degrees of waveform skipped at time = 0 seconds. The same applies if radians are used.
Now, how does this apply to an amplifier or opamp?
An opamp usually has two inputs that work in opposition to each other. Therefore, one would produce a positive output voltage for a postive output voltage and the other produces a negative output voltage for a positive input. The latter input, since it changes the sign of the output when compared to the input, is said to be inverting. 'To invert' means to turn upside down.
For the mains voltage, the phase angle is the parameter Φ.
The formula for this is: V = U.Sin(2πft + Φ)
U: peak voltage
V: instantaneous voltage at t seconds
f: frequency in Hertz (Cycles per second)
t: time in seconds
Φ: the phase angle in Radians as we are using π
As you can see, the term within the bracket reduces to Φ at t = 0 seconds.
Note: a phase angle can also be negative but this stems from the definition of an angle, not from electronics.
The phase is simply the percentage multiplied by 360 degrees of waveform skipped at time = 0 seconds. The same applies if radians are used.
Now, how does this apply to an amplifier or opamp?
An opamp usually has two inputs that work in opposition to each other. Therefore, one would produce a positive output voltage for a postive output voltage and the other produces a negative output voltage for a positive input. The latter input, since it changes the sign of the output when compared to the input, is said to be inverting. 'To invert' means to turn upside down.
For the mains voltage, the phase angle is the parameter Φ.
The formula for this is: V = U.Sin(2πft + Φ)
U: peak voltage
V: instantaneous voltage at t seconds
f: frequency in Hertz (Cycles per second)
t: time in seconds
Φ: the phase angle in Radians as we are using π
As you can see, the term within the bracket reduces to Φ at t = 0 seconds.
Note: a phase angle can also be negative but this stems from the definition of an angle, not from electronics.
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