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What effect does the bypass capacitor have on the output impedance of the amplifier?
Wiki User
∙ 11y ago
The quantity of specific information included in the question is exceeded only by
the quantity of vital, relevant information that's never mentioned.
Are you talking vacuum-tube or transistor amplifier ? What's the configuration of the
amplifier, i.e., which terminal of the active device is 'common' to input and output ?
And where is the bypass capacitor in the circuit ?
I'll take a wild stab and assume that you have a common-emitter amplifier, with the
capacitor bypassing the bias resistor in the emitter branch. If that's the case, then
the resistor is supposed to be there only to set the DC Q-point, but every effect it
could have on small-signal performance would be an effect that you don't want ...
it would increase the output impedance, and any impedance common to input and
output always reduces the gain.
So one of the effects of the bypass capacitor is to reduce the output impedance
of the stage.
(If Dingobot comes along now and flags this for gibberish, that'll be my first clue
that after all these years, I don't actually remember this stuff too well.)
Wiki User
∙ 11y ago
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What is the effect of bypass capacitor on frequency response?
Gain in a CE configuration of a BJT is collector resistance divided by emitter resistance, subject to the limit of hFe. The emitter bypass capacitor will have lower impedance at high frequency, so the gain will be higher at higher frequency, making this a high-pass amplifier.
What is the effect in an input impedance of a common emitter amplifier if the bypass capacitor is removed?
The input impedance of a common emitter amplifier is hfe (or beta) times the sum of the emitter resistance, re = kT/qIc, plus the external impedance in series with the emitter. k - Boltzmann's constant, T - degrees Kevin, q - electron charge, Ic - collector current makes the intrinsic emitter resistance about 26 ohms at 1 ma. If the bypass capacitor impedance is much less than 26 ohms at the frequency of interest, then for a beta = 100 transistor operating at 1ma the input impedance is about 2600 ohms at low frequencies ie. 100 * (26 + 0). Say the external emitter resistance is 1K ohm and you remove the bypass cap. The total emitter resistance is now 26+1000 or 1026 ohms and the input impedance is now 100 * (26+1K ohms) or 102.6K ohms.
What is the effect on voltage gain in a common emitter amplifier when the decoupling capacitor is removed?
The emitter bypass capacitor, in a typical common emitter configuration, increases gain as a function of frequency, making a high pass filter. Removing the capacitor will remove the gain component due to frequency, and the amplifier will degrade to its DC characteristics.
What is effect on amplifier output if you increase input impedence?
Impedence is synonymous with resistense. Greater the I, lesser the outputNo.First, it's *resistance* and *impedance*.Now, if the amplifier is a current amplifier, the above makes sense. (higher Zin, less Iin for a constant Vin).But if it's a purely voltage amplifier, it only responds to the input voltage, so the impedance (so long as it's not affecting the source/driving device) will have no effect on a purely voltage-amplifying amplifier.
How you can eliminate loading effect in amplifiers?
By increasing the input impedance of amplifier.
What is collector bypass capacitor?
A: It is not a bypass it is a negative feedback to effect the input voltage, Bias is when a DC voltage is applied to insure proper operation
What are the applications of jfet transistor?
The Junction Field Effect Transistor (JFET)exhibits characteristics which often make it more suited to a particular application than the bipolar transistor. Some of these applications are: - High Input Impedance Amplifier - Low-Noise Amplifier - Differential Amplifier - Constant Current Source - Analogue Switch or Gate - Voltage Controlled Resistor
Loading effect in RC coupled amplifier?
Loading of Rc coupled amplifier occurs, if you doesnt use coupling capacitors...... If avoiding input coupling capacitor the amplifier will load the function generator.. For more details go to http://mycircuits9.blogspot.com
Is mosfet voltage controlled capacitor or inductor?
It's a Field Effect Transistor. I personally wouldn't consider it either of those options; if I had to pick one, it's more inductor-like (in that it has impedance).
Is loading effect more when load impedance is less then source impedance?
The higher the mismatch between the load impedance and source impedance, the higher the loading effect.
What is the difference between voltage gain obtained with bypass capacitor and without the bypass capacitor?
A: A TRANSISTOR gain is determined by current flow on the collector by adding a resistor to the emitter this current flow is reduced by adding or bypassing this resistor with a capacitor the net effect is that this emitter resistor will be reduced in value as frequency increases therefore change gain as a function of frequency input
What is the effect of capacitor in the output noise?
The capacitor on it's own is of no use, it is always used in an RC or LC configuration normally in audio frequency's the RC is used to filter the noise down to earth where the RC circuit have to resonate at the same frequency as the noise, the lower the frequency the larger the value of the capacitor
