Basic electronics lecture 6
- 2. Recalling amplifiers Simply the amplifiers are called as an amp The amplifier is an electronic device used to increase the signal of current, voltage and power The function of the amplifier is by using the power from the power supply and longer altitude, it controls the output signal with the help of input signal An amplifier modulates the out of the power supply is based on the properties of the input signal 2
- 3. Class A amplifiers The class A amplifiers are simple designed amplifiers and this amplifier is most commonly used amplifiers Basically, the class A amplifiers are the best class amplifiers because of their low distortion levels This amplifier is the best in the audio sound system and in most of the sound system use the class A amplifier 3
- 4. Contd. The class A amplifiers are formed by the output stage devices which are biased for the class A operation By comparing the other classes amplifiers to class A amplifier has the highest linearity. 4
- 5. Class B amplifiers The class B amplifiers are the positive and negative halves of the signals, that are allocated to the different parts of the circuits and the output device switched ON and OFF continuously The basic class B amplifiers are used in two complementary transistors 5
- 6. Class B amplifier These two transistors of each half of the waveform with its output are configured in a push-pull type arrangement Hence the each amplifier amplifies only half of the output waveform In the Class B amplifier, if the input signal is positive, then the positively biased transistor conduct and the negative transistor is switched OFF. 6
- 7. Contd. If the input signal is negative, then the positive transistor switches OFF and negative biased transistor turn ON Hence the transistor conduct half of the time whatever it may be like positive or negative half cycle of the input signal. 7
- 8. Class AB The class AB is the combination of class A and class B amplifier The class AB amplifiers are using commonly in the audio power amplifiers The conduction angle of Class AB amplifier is in between 180 to 360 which is depending on the bias point The advantage of the small bias voltage is to give in series resistance and diode. 8
- 9. Class C amplifier The design of class C amplifier has a great efficiency and poor linearity In the previous amplifiers, we have discussed the class A, B and AB are the linear amplifiers The class C amplifier is a deeply biased hence the output current is zero for more than the one-half of the input signal and the transistor idling at the cut off point 9
- 10. Class D amplifier The class D amplifier is non-linear switching amplifiers This amplifier can reach 100% efficiency in theoretically and there is no period during the cycle The voltage and the current waveforms overlap, current is drawn only with the help of transistor which is in ON state These amplifiers are also called as the digital amplifiers 10
- 11. Class F amplifier The F amplifiers are used to increase the efficiency and output by the harmonic resonators in the form of output network and to shape the output waveform in a square wave The class F amplifiers have more than 90% of efficiency if the infinite harmonic tuning is used 11
- 12. Class S amplifier The class S amplifiers are similar operations to the class D amplifiers These amplifiers are Non-linear switching mode amplifiers It converts the analog input signals to the digital square wave pulses by using the delta- sigma modulations. 12
- 13. Contd. It amplifies them in to increase the output power by the help of band pass filter The digital signal of the switching amplifier is fully in ON or OFF state and its efficiency can reach 100% 13
- 14. Class T amplifier The class T amplifiers are designed with a type of digital switching amplifiers Now a days these amplifiers became more popular This amplifier converts the signal from analog signal to the digital pulse width modulation signal and the amplification increase the efficiency of an amplifiers 14
- 15. Class G amplifier The enhancement of class G Amplifier is the basic of Class AB Amplifier The class G amplifier used in the multiple power supply rails of different voltages Automatically switches between the supply rails as the input signal changes The contact switching decreases the average power consumption hence, the power loss is produced by the wasted heat 15
- 16. 16