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

Role of gis in distribution reforms, Role of GIS in Distribution Reforms: ...

Role of GIS in Distribution Reforms: You will agree which distribution is the weakest link in the chain of power supply and has been identified as the key focus area in power

Balanced score card and key performance indicators, Balanced Score Card and...

Balanced Score Card and Key Performance Indicators Every successful organization measures its performance across the subsequent parameters, for dissemination to all stakeholde

Measuring with an oscilloscope, 1. Introduction : Theory:   The ...

1. Introduction : Theory:   The voltage measured across a load follows the Ohm's law which says that the current passing through a conductor between two points is direct

Technical loss reduction - power supply, Technical Loss Reduction - Power S...

Technical Loss Reduction - Power Supply 1. Technical loss reduction could be achieved through several measures such as network reconfiguration, load balancing, network recondu

Long-term plans for technical loss reduction, Long-Term Plans for Technical...

Long-Term Plans for Technical Loss Reduction Long-term measures for technical loss reduction include all measures that require to be taken for the improvement of quality and r

Transfer function of radiator, hi, i want to know the transfer function of ...

hi, i want to know the transfer function of a radiator

Induced emf, applications of dynamically induced emf

applications of dynamically induced emf

What is the significance of source gate cutoff voltage, Q. What is the sign...

Q. What is the significance of source gate cutoff voltage? The source gate cutoff voltage is also called pinch off voltage. It is obtained when VDS increases and approaches a l

Factors involved in the voltage build up of shunt generator, Q.   List and ...

Q.   List and explain the factors involved in the voltage build up of shunt generator. Ans. following factors are involved in voltage build up of shunt generation

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