What is sinewave distortion? is it top and bottom flattening or is it unequal mark space ratio? i.e the rise time being different to the fall time?
Neil.
Neil.
Then you should take note of phase distortion..........all I need it for is to stuff into filters and buffers.............
Is this impedance mismatch?The third contributor is distortion. Distortion occurs when the instantaneous output amplitude is an incorrect match with the input.
It can be any and/or all of the above. The bottom line is harmonic distortion. A pure sine wave has one and only one frequency and no harmonics. Causes of distortion can be legion.What is sinewave distortion? is it top and bottom flattening or is it unequal mark space ratio? i.e the rise time being different to the fall time?
Neil.
The harmonic distortion are create because of a nonlinearity in amplifier.Is this impedance mismatch?
Cross over distortion will indeed show up as harmonics in the Fourier series of the waveform. The harmonics will be different, of course, from those caused by other forms of non-linear distortion.....................................
The third contributor is distortion. Distortion occurs when the instantaneous output amplitude is an incorrect match with the input.
As with noise there are several forms and sources of distortion.
The form of distortion called harmonic distortion is what I think you mean by sine wave distortion. Here the Fourier series of the output is different from the Fourier series of the input. There are other forms of distortion, for instance cross over distortion, that cannot be represented in this manner.
I think this is a language mismatch.Quote:
The third contributor is distortion. Distortion occurs when the instantaneous output amplitude is an incorrect match with the input.
Is this impedance mismatch?
This makes me imagine about transmission line. If wires are very long compared to wavelength (longer than 1/10 wavelength) then the instantaneous signal voltages at the source and the load is not equal and this maybe causes reflection.Distortion occurs when the instantaneous output amplitude is an incorrect match with the input.
Av changes according to operating point.The harmonic distortion are create because of a nonlinearity in amplifier.
For example the voltage gain of a Common emitter is a signal level dependent.
Av = gm*Rc ≈ 40 * Ic *Rc
For example if we have CE amplifier with Vcc = 10V; Rc = 10K and Ic = 500μA and Vce = 5V.
So the average gain is equal to Av ≈ 40 * 500μA * 10KΩ = 200V/V
If the input signal swings positive so that the collector current increases to 800μA and the collector voltage falls to Vce = 2V, the incremental gain
will be 40*800μA*10K = 320V/V
If the input signal swings negative so that the collector current
falls to 200μA and the collector voltage rises to 8V, incremental gain will fall to 40*200μA*10K = 80V/V. The incremental gain of this stage has thus
changed by over a factor of 4 when the output signal has swing 6V peak-to-peak. This create a high level of distortion in the output signal.
I did say it was complicated. There are several forms of distortion, not all of which show up in a harmonic analysis.Cross over distortion will indeed show up as harmonics in the Fourier series of the waveform. The harmonics will be different, of course, from those caused by other forms of non-linear distortion.
But even for small signal Vin = 10mV peak the harmonic distortion will be quite large (THD<10%). Because the voltage gain is not constant, gain varies with the input signal.Av changes according to operating point.
Av= -gm.Rc
And transconductance, gm, of transistor depends on DC operating point. If the Q point moves towards the direction so that Ic increases, then gm will increase, respectively.
Relating to input level, because the Ic-Vbe characteristic only be considered as linear in input signal are small. As input signal are large the characteristic is no longer linear anymore.
Are my understanding correct?
I disagree with you, negative feedback can reduce this "deadzone".However no amount of negative feedback can cure crossover distortion. Again this is because the effect occurs near zero amplitude. Since there is zero or near zero output there is nothing to feed back!
How is AM or FM modulation, distortion? Distortion is usually consider to be the unwanted portion of a waveform. I would not call the intentional periodic variation of the amplitude or frequency of a carrier wave in response to a modulation signal "distortion".An interesting intentional use of sine wave distortion is employed in modulation. AM & FM being examples.
Where are the infinite number of discontinuities? I don't see any discontinuities; at most I see discontinuities in the first derivative:In crossover distortion there are an infinite number of discontinuities.
by Jake Hertz
by Jake Hertz
by Duane Benson