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The best way to answer this question might be to consider the consequences if the input impedance was low: with a low input impedance, (signifficant) current would start flowing, and the amplifier would draw energy from the signal sources. None of the typical signal sources is designed to deliver energy on its outputs (after all, this is where the amplifier itself comes in). It is certainly possible to think that some of these sources might be changed to deliver some energy, but this is not the case with present-time tuners, CD players, microphones, and so forth. Assuming that the energy supply was not the issue, just to ponder this theoretical scenario a little further, the fact that current would flow from the source to the amplifier would also make the signal more vulnerable to the characteristics of the cable that connects the two. The high impedance of an amplifier input draws no energy, thereby avoiding these issues. It is the amplifier's task to convert a very low energy, voltage-driven signal into an higher energy output signal (driving the speakers which themselves have a very low impedance). ---- The way I typically think about this is to consider connecting a load to a Thevenin equivalent circuit [1]. The voltage across the load is given by the voltage divider formula (Vload = Vsrc * Rload/(Rload+Rthevenin)). If there is a very low load impedance--this means the amplifier has a very low input impedance--most of the source voltage will drop over the Thevenin equivalent resistance. With a very high input impedance, however, the majority of the signal voltage will be transferred from the source to the load because in the above equation, if Rload >> Rthevenin, Vload is approximately equal to Vsrc. if an amplifier has low impedance input the f/b must be low impedance also which make it in practical to use. The hi impedance of a typical amplifier is because the input is one two diodes basically operating on it exponential curve. Making it virtual the same as the other diode. for a differential amplifier. Boltzmann constant will define the impedance of a single diode.
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∙ 14y ago
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∙ 14y agoTo get all the voltage from a source to a target without loss you need voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is more than ten times higher then the output impedance.
An input impedance is called also a load impedance or an external impedance.
An output impedance is called also a source impedance or an internal impedance.
Wiki User
∙ 14y agoTo get all the voltage from a source to a target without loss you need voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is more than ten times higher then the output impedance.
An input impedance is called also a load impedance or an external impedance.
An output impedance is called also a source impedance or an internal impedance.
Wiki User
∙ 13y agoHigh input impedance is essential for voltage bridging. No power transfer and no heavy load.
Scroll down to related links and look at "Impedance bridging - Wikipedia".
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∙ 15y agoHigh input impedance is used with devices that need to measure a voltage without affecting the thing being measured. If it has a lower impedance, it would load down the source and affect it.
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∙ 14y agoHigh input resistance in an amplifier means that the driving signal is not loaded down and distorted as much as it would be if the impedance were low.
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∙ 14y agoAMPLIFIER DO AMPLIFY not only the signal but also the power FOR POWER TO BE DELIVER A LOW OUTPUT SOURCE IMPEDANCE IS DESIRABLE
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∙ 11y agoVoltage amplifier have high input impedance and low output impedance to use impedance bridging. The load gets the high voltage which comes from the source output.
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Compared to bipolars FETs have-a high input impedance b low input impedance c same input impedance?
FET s have very high input impedance when compared with Bipolar transistors.
How do design a high voltage voltmeter?
Use a voltage divider and an standard high input impedance voltmeter connected to the low voltage output tap of the divider. Just check that: a) the voltage divider has enough resistance to minimize loading of the voltage source (The voltage divider resistance should be as high as possible). b) the voltmeter's input impedance is at least 10-20 times larger than the output resistance (impedance) of the divider. If necessary add a high-input impedance amplifier or a transducer between the divider output and the voltmeter. What is high voltage for you?
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
Which is better high input impedance or low input impedance and why?
That depends on the output impedance. In electronic we use voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is more than ten times higher then the output impedance. An input impedance is called also a load impedance or an external impedance. An output impedance is called also a source impedance or an internal impedance.
What are the main features of instrumentation amplifier in instrumentation system?
High Common Mode Rejection Ratio is the main feature of instrumentation amplifier! And other features are high input impedance, low output impedance, high slew rate, low power consumption, more accurate, easier gain adjustment, low thermal and time drift.
In a multistage amplifier input impedance is high and output impedance is low justify the statement?
no. input impedance is low & output impedance is high
Why the input resistance of opamp is high?
Because op amp consist differential amplifier and they posses high input impedance so that op-amp also posses high input impedance.
Why a high input impedance?
A circuit (an amplifier) typically has a high input impedance so that it does not unduly load the input circuit. Any such load could cause distortion, and that is generally not desired.
What type of transformer configuration will you select to design a high input impedance and low output impedance amplifier?
main volage
Why input impedance of any amplifier should very high?
To get all the audio voltage from a source to a target without loss you need voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is at least ten times higher then the output impedance.An input impedance is called also a load impedance or an external impedance.An output impedance is called also a source impedance or an internal impedance.
What is a common base NPN amplifier?
A common base NPN amplifier is used for high frequency applications as the base minimize oscillations at high frequency, separates the input and output. In a common base NPN amplifier the voltage gain is high, relatively low input impedance and high output impedance compared to the common collector.
Why input resistance of voltage amplifier is infinity?
For the successful amplification of the input signal the opamp should have ideally infinite input impedance . It should act like a buffer amplifierBUFFER amplifier--------------------->1.input impedance infinity2.output impedance zerothe reason is thatAny signal source will have source impedancefor the signal not to get lost and dropped across source impedance we ideally insert infinite impedance in series with it which makes the whole drop across the infinite impedance but not across the sourcesimilarly at the output zero impedance is used where in no part of the signal should be left behind in the op amp as a drop
State the application of RC coupled amplifier?
To increase the power gain ,high input impedance,low output impedance,and increase the weaken signal
Compared to bipolars FETs have-a high input impedance b low input impedance c same input impedance?
FET s have very high input impedance when compared with Bipolar transistors.
How do design a high voltage voltmeter?
Use a voltage divider and an standard high input impedance voltmeter connected to the low voltage output tap of the divider. Just check that: a) the voltage divider has enough resistance to minimize loading of the voltage source (The voltage divider resistance should be as high as possible). b) the voltmeter's input impedance is at least 10-20 times larger than the output resistance (impedance) of the divider. If necessary add a high-input impedance amplifier or a transducer between the divider output and the voltmeter. What is high voltage for you?
Why should the input resistance of a instrumentation amplifier be as high as possible?
Input resistance answerRequired because sensors typically have a high or unbalanced source impedance. It is ideal to have no current flow through and OP amp therefore ideal to have infinite input impedance. If current is flowing through this could cause an error in the output. Please comment on this, not sure if correct.Comment: If you are not sure about your facts, I see little point in offering an answer.AnswerConnecting an amplifier to a transducer/sensor inevitably changes the conditions of the phenomena being measured. This is due, primarily, to the amplifier drawing, an albeit small, current from the transducer. The higher the amplfier's input impedance, the lower the current drawn, and hence the less the disturbance to the original conditions.
What is small signal amplifier?
As the name suggests, it amplifies a small signal. It ususally has a very high input impedance, to avoid affecting the source signal.
