Briefly discuss about cascaded amplifier, Electrical Engineering

Assignment Help:

Q. Briefly discuss about ‘Cascaded Amplifier' using a diagram?

Amplifiers are cascaded when the output of the first is the input to the second. The combined gain is

1687_Briefly discuss about Cascaded Amplifier.png

where vi2 = vo1. The total gain is the product of the cascaded amplifier stages. The complication in calculating the gain of cascaded stages is the non-ideal coupling between stages due to loading. Two cascaded CE stages are shown below.

2199_Briefly discuss about Cascaded Amplifier1.png

Because the input resistance of the second stage forms a voltage divider with the output resistance of the first stage, the total gain is not the product of the individual (separated) stages.

The total voltage gain can be calculated in either of two ways. First way: the gain of the first stage is calculated including the loading of ri2. Then the second-stage gain is calculated from the output of the first stage. Because the loading (output divider) was accounted for in the first-stage gain, the second-stage gain input quantity is the Q2 base voltage, vB2 = vo1. Second way: the first-stage gain is found by disconnecting the input of the second stage, thereby eliminating output loading. Then the Thevenin-equivalent output of the first stage is connected to the input of the second stage and its gain is calculated, including the input divider formed by the first-stage output resistance and second-stage input resistance. In this case, the first-stage gain output quantity is the Thevenin-equivalent voltage, not the actual collector voltage of the stage-connected amplifier. The second way includes interstage loading as an input divider in the gain of the second stage while the first way includes it as an output divider in the gain of the first stage.

By cascading a CE stage followed by an emitter-follower (CC) stage, a good voltage amplifier results. The CE input resistance is high and CC output resistance is low. The CC contributes no increase in voltage gain but provides a near voltage-source (low resistance) output so that the gain is nearly independent of load resistance. The high input resistance of the CE stage makes the input voltage nearly independent of input-source resistance. Multiple CE stages can be cascaded and CC stages inserted between them to reduce attenuation due to inter-stage loading.


Related Discussions:- Briefly discuss about cascaded amplifier

Differentiate between an integrator and differentiator, Q . Differentiate b...

Q . Differentiate between an integrator and differentiator? Integrators 1 Integrators are circuits in which output voltage is proportional to the integral of the input.

Synchronization, Synchronization:  Whatever type of weep is used, it must ...

Synchronization:  Whatever type of weep is used, it must be synchronized with the signal being measured. Synchronization has to be done to obtain a stationary pattern. This requir

Matlab magnetic field, i have an assignment related to magnetic field i ha...

i have an assignment related to magnetic field i have attached the( MRI assignment sheet)[1] please read it carefully in the assignment 2 methods to get the results - one by

Electronic instrumentation and measurements, why is a delay line used in th...

why is a delay line used in the vertical selection of oscilloscope?

Passive filters, Passive filters: Passive implementations of linear fi...

Passive filters: Passive implementations of linear filters are based upon combinations of inductors (L), resistors (R), and capacitors (C). These sorts are collectively termed

Scatter Diagrams - Quality Tools for Improvement, Scatter Diagrams - Qualit...

Scatter Diagrams - Quality Tools for Improvement Scatter diagrams are graphical tools which attempt to depict the influence in which one variable has on another. A general dia

Find the transfer function of a linear system, Q. The response y(t) of a li...

Q. The response y(t) of a linear system to an excitation x(t) = e -2t u(t) is y(t) = (t + 2)e -t u(t). Find the transfer function.

100 line exchange with two-motion line finders, In this design, there are 2...

In this design, there are 24 line finders. If any of the 100 subscribers has to get access to any of 24 two-motion selectors, it is necessary that every line finder is capable of r

Signals and spectral analysis, Q. Signals and spectral analysis? Figure...

Q. Signals and spectral analysis? Figure shows the functional block diagram of a signal-processing system. The information source may be a speech (voice), an image (picture), o

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