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because +feedback amplify noise also.it amplify the noise to input ratio by[1/(1-G.H)].
WHERE g=open loop gain
H=feedback gain
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What is negative feedback in an amplifier?
feedback that reduces gain to help stabilize amplifier operation. gain is easy and cheap to get, stability isn't. its a tradeoff. so amplifier is deliberately designed with much more gain than needed and negative feedback sacrifices some of that gain to stabilize it.
Advantages of negative feedback amplifier?
Most practical amplifier circuits use negative feedback for the following practical benefits: Stabilization of voltage gain, decreasing output impedance, increasing input impedance, decreasing distortion, increasing bandwidth.
The use of swamping resistor in differential amplifier?
the use of swamping resisters in amplifier is in order to protect the amplifier from high temperatures
Why use a npn transistor in a common emitter bjt single stage amplifier circuit?
You can use an npn or a pnp bjt in a common emitter amplifier circuit. The decision of which one to use is based on whether you want the collector and base to be more positive (npn) or more negative (pnp) than the emitter.
What is opamp?
An operational amplifier, which is often called an op-amp, is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output.[1] An op-amp produces an output voltage that is typically millions of times larger than the voltage difference between its input terminals.Typically the op-amp's very large gain is controlled by negative feedback, which largely determines the magnitude of its output ("closed-loop") voltage gain in amplifier applications, or the transfer function required (in analog computers). Without negative feedback, and perhaps with positive feedback for regeneration, an op-amp essentially acts as a comparator. High input impedance at the input terminals (ideally infinite) and low output impedance at the output terminal(s) (ideally zero) are important typical characteristics.Op-amps are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices. Many standard IC op-amps cost only a few cents in moderate production volume; however some integrated or hybrid operational amplifiers with special performance specifications may cost over $100 US in small quantities. Op-amps sometimes come in the form of macroscopic components, (see photo) or as integrated circuit cells; patterns that can be reprinted several times on one chip as part of a more complex device.The op-amp is one type of differential amplifier. Other types of differential amplifier include the fully differential amplifier (similar to the op-amp, but with two outputs), the instrumentation amplifier (usually built from three op-amps), the isolation amplifier (similar to the instrumentation amplifier, but which works fine with common-mode voltages that would destroy an ordinary op-amp), and negative feedback amplifier (usually built from one or more op-amps and a resistive feedback network).
Can we use positive feedback in amplifiers?
Yes because an amplifier with positive feedback is an oscillator.
What is negative feedback in an amplifier?
feedback that reduces gain to help stabilize amplifier operation. gain is easy and cheap to get, stability isn't. its a tradeoff. so amplifier is deliberately designed with much more gain than needed and negative feedback sacrifices some of that gain to stabilize it.
Why do you use feedback?
The voltage gain,input impedance,output impedance,bandwidth etc. are the characteristics of amplifier's. these are more or less constant for a given amplifier. These parameters are required to be controlled. This can be done by using feedback that's why we use feedback.
What is use of negative feedback in amplifier?
Reduce the distortion in output signal.
What is the use of finding the bandwidth of an amplifier?
A: Any amplifier will have greater band with if operated open loop. It will also be very unstable so negative feedback is implemented for that reason. There is some drawback when feedback the band width of the amplifier decreases, So is important to find out if the amplifier when stable will it have the band width required
Can negative feedback amplifier work as a oscillator if yes how if no why?
All negative feedback systems, whether they be electronic, biological, or anything else, work by applying a negative feedback to the source signal, which is proportional in some way to the source signal. If the factor by which the amplifier corrects is high enough, oscillation will result (perhaps even runaway oscillation) How you make it happen depends upon the amplifier you use however -- though most work similarly enough. You could use a delay between output and feedback, or you could rely on a large amplifier gain.
Advantages of negative feedback amplifier?
Most practical amplifier circuits use negative feedback for the following practical benefits: Stabilization of voltage gain, decreasing output impedance, increasing input impedance, decreasing distortion, increasing bandwidth.
What type of feedback used in the oscillator circuit?
There are many different types of oscillator circuits, the majority of which use positive feedback.
Can you use feedback in transmission lines as you use in operational amplifier?
yes i used feedback path in the op-amp because if you need the standard or desired output then you have to compare it with the applied input then and then only op-amp gives you the constant output.
Reason use an op amp in a closed loop control system?
Differential Amplifier or Summing Amplifier are usually used in a closed loop control system. The error signal will be the DIFFERENCE between the setpoint value and feedback value for Differential Amplifier. Whereas for Summing Amplifier, the error signal will be the difference between the setpoint value and feedback value only if one of the value is inverted in polarity. Another reason Op Amp is used: amplify the error signal as error signals are usually very small. Hope this helps.
What are the values so that over all gain is 10 in instrumentation amplifier?
You need a divider that is 10 to 1. You could use 10 megohms in the feedback and 1 megohm in the bottom leg. Since you are probably talking about an operational amplifier, you need this in both legs.
What is the best headphone to use with your guitar amplifier for feedback?
You could try the C Tech Pocket Rockit V2 Guitar Headphone Amplifier. It is made for guitars, and has great sound without too many complicated gadgets.It also received good reviews at the Amazon website
