The field of Affective Computing AC expects to narrow the communicative gap between the highly emotional human and the emotionally challenged computer by developing computational systems that recognize and respond to the affective states of the user. Affect-sensitive interfaces are being developed in number of domains, including gaming, mental health, and learning technologies. Emotions are part of human life.
The classes are based on the proportion of each input cycle conduction angle during which an amplifying device passes current.
The angle of flow is closely related to the amplifier power efficiency. In the illustrations below, a bipolar junction transistor is shown as the amplifying device. The active element remains conducting  all of the time. Amplifying devices operating in class A conduct over the entire range of the input cycle.
A class-A amplifier is distinguished by the output stage devices being biased for class A operation. Subclass A2 is sometimes used to refer to vacuum-tube class-A stages that drive the grid slightly positive on signal peaks for slightly more power than normal class A A1; where the grid is always negative  .
This, however, incurs higher signal distortion[ citation needed ].
Advantages of class-A amplifiers[ edit ] Class-A designs can be simpler than other classes insofar as class -AB and -B designs require two connected devices in the circuit push—pull outputeach to handle one half of the waveform whereas class A can use a single device single-ended.
Because the device is never 'off' there is no "turn on" time, no problems with charge storage, and generally better high frequency performance and feedback loop stability and usually fewer high-order harmonics. The point where the device comes closest to being 'off' is not at 'zero signal', so the problems of crossover distortion associated with class-AB and -B designs is avoided.
Best for low signal levels of radio receivers due to low distortion. Disadvantage of class-A amplifiers[ edit ] Class-A amplifiers are inefficient. Inefficiency comes from the standing current that must be roughly half the maximum output current, and a large part of the power supply voltage is present across the output device at low signal levels.
If high output power is needed from a class-A circuit, the power supply and accompanying heat becomes significant. For every watt delivered to the loadthe amplifier itself, at best, uses an extra watt.
For high power amplifiers this means very large and expensive power supplies and heat sinks. Class-A power amplifier designs have largely been superseded by more efficient designs, though their simplicity makes them popular with some hobbyists.
There is a market for expensive high fidelity class-A amps considered a "cult item" among audiophiles  mainly for their absence of crossover distortion and reduced odd-harmonic and high-order harmonic distortion.
Class A power amps are also used in some "boutique" guitar amplifiers due to their unique tonal quality and for reproducing vintage tones.
Single-ended and triode class-A amplifiers[ edit ] Some hobbyists who prefer class-A amplifiers also prefer the use of thermionic valve tube designs instead of transistors, for several reasons: Single-ended output stages have an asymmetrical transfer functionmeaning that even-order harmonics in the created distortion tend to not cancel out as they do in push—pull output stages.
For tubes, or FETsmost distortion is second-order harmonics, from the square law transfer characteristicwhich to some produces a "warmer" and more pleasant sound.Scattering parameters or S-parameters (the elements of a scattering matrix or S-matrix) describe the electrical behavior of linear electrical networks when undergoing various steady state stimuli by electrical signals..
The parameters are useful for several branches of electrical engineering, including electronics, communication systems design, and especially for microwave engineering. This thesis discusses the design, fabrication, and testing of a high efficiency, dual band radio frequency power amplifier.
While it is difficult to demonstrate an exact mode of. Class-F Power Amplifier with Maximized PAE A Master Thesis to RF power. With PAE increased, the device is able to output the same amount of power IEEE PA design contest.
Conclusion The thesis has shown the effectiveness of the Class-F PA to boost up PAE by preventing. The main goals of the Thesis Master are to design and assembly an E class RF power amplifier to operate at 2GHz band to transmit signal of wideband wireless technology.
AMPLIFIER BY USING DOHERTY CONFIGURATION a thesis submitted to the department of electrical and DESIGN OF A HIGH EFFICIENCY POWER AMPLIFIER BY USING DOHERTY CONFIGURATION KAZIM PEKER M.S.
in Electrical and Electronics Engineering 2 RF AMPLIFIERS 5. CMOS HIGH EFFICIENCY RF POWER AMPLIFIER by A THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Electrical Engineering and Computer Engineering College of Engineering KANSAS STATE UNIVERSITY Class-A/D and Class-E Power Amplifier: Design and Simulation