Frequency response of amplifiers, Electrical Engineering

Assignment Help:

Q. Frequency response of amplifiers?

All amplifiers exhibit variations of performance as the signal frequency is changed. The frequency response of an amplifier may be defined as the functional dependence of output amplitude and phase upon frequency, for all frequencies. Invariably there is a maximum frequency above which amplification does not occur. Depending on the design of the circuit, there may also be a lower frequency limit below which amplification disappears. The range of frequencies over which significant amplification of themagnitude is obtained is known as the passband, which is bounded by the upper cutoff frequency and the lower cutoff frequency (if one exists).Dc-coupled amplifiers, in which the stages are coupled together for all frequencies down to zero, have no low-frequency limit. On the other hand, circuits containing coupling capacitors that couple stages together for ac while isolating them for dc are limited in their low-frequency response. The high-frequency deterioration of the voltage gain is due to the effect of capacitances that are internal to the transistor.

786_Frequency response of amplifiers.png

Figure shows a typical frequency response of a voltage amplifier.While most often the magnitude of the gain is discussed (because it defines the frequency range of useful gain), the phase response becomes important for transient calculations. The midband region is the range of frequencies where gain is nearly constant. Amplifiers are normally considered to operate in this useful midband region. The bandwidth of an amplifier is customarily defined as the band between two frequencies, denoted by ωH and ωL, which corresponds to the gain falling to 3 dB below the midband constant gain. Thus,

W3dB = ωH - ωL

which is shown in Figure. When both ωL and ωH have significant values, the amplifier is known as a bandpass amplifier. A narrow-bandpass amplifier is one in which W3dB is small relative to the center frequency of the midband region. In a low-pass unit (dc amplifier) there is no low 3-dB frequency.


Related Discussions:- Frequency response of amplifiers

The parallel resistance rule, The Parallel Resistance rule ...

The Parallel Resistance rule Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Electrical machine, Explain the principle of induction applied in electrica...

Explain the principle of induction applied in electrical machine

How transistor will be used as an amplifier, (a) How transistor will be use...

(a) How transistor will be used as an amplifier? (b) Give relation between α and β? (c) Show the biasing arrangement for the PNP transistor in common base configuration, so t

Explain resistance-capacitance coupling, Q. Explain Resistance-capacitance ...

Q. Explain Resistance-capacitance coupling? It is the most commonly used coupling in discrete device amplifier as it is least expensive and has satisfactory frequency response.

Phisics, deriving formula of the frictional force

deriving formula of the frictional force

Operation of zener diode, Operation of Zener Diode The Zener diode's o...

Operation of Zener Diode The Zener diode's operation depends upon the heavy doping of its p-n junction permitting electrons to tunnel from the valence band of the p-type mater

Determine tick of the material, Tick off the material, which is different f...

Tick off the material, which is different from the group (A) Constantan.            (B) Manganin. (C) Nichrome.               (D) Brass. Ans: Tick off the materi

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd