As it requires large power for operation, thus operated under class B or C operation.įurther, we can classify the small signal tuned amplifier in the following categories: Large signal tuned amplifiers are used for amplification purpose but for the radio frequency signal having a large magnitude. As the power needed for its operation is small, thus operated under class A operation. Small signal tuned amplifiers are used to amplify signals of small magnitude at radio frequency. The tuned amplifier is majorly classified into two categories: Let’s have a relationship between Q factor and bandwidth of a tuned amplifier. The bandwidth of a tuned amplifier is defined as that frequency range where the gain of the amplifier reduces to 70.7% of its highest value. Total loss in a coil is expressed by the series combination of inductor along with leakage resistance. These losses are represented in the form of resistance.Ĭopper, eddy current and hysteresis losses constitute the total loss of a coil. This coil is not purely inductive practically, due to losses associated with it. The resonant circuit in a tuned amplifier contains coil. The resonance curve will show the sharper response for a higher value of Q. To sum up, basically, Q factor is the measure of energy storing efficiency of an inductor. It basically measures the purity of an inductor and is a unitless quantity. Thus, for a better Q factor, it is needed that the resistance must be low. As an inductor along with inductance possesses a small amount of resistance. The quality factor is given as the ratio of coil impedance(reactance) of an inductor to its resistance. The phenomenon is known as resonance and the particular frequency is known as resonant frequency. The frequency at which inductive reactance becomes equal to capacitive reactance, the circuit behaves as purely resistive. Let’s have a look at the basic circuit of a tuned amplifier: However, a sharp fall is noticed for the frequency other than the resonant frequency. Thus, we can see the response curve is at its maximum in case of the resonant frequency. It is to be noted that the response of the tuned circuit is maximum in case of the resonant frequency. The frequency response curve for a tuned amplifier is similar to that of the resonance curve of a tuned circuit. ![]() The resonance frequency of a tuned circuit is given as Tuned amplifiers are specifically designed for narrow bandwidth frequency signal. ![]() This is so because employing a resonant circuit as load offers high impedance and gain of the transistor amplifier is a quantity dependent on load impedance. It is noteworthy here that tuned amplifiers provide high gain. The resonant frequency of the tuned circuit will be the centre frequency of the selected frequency band. Thus, it allows selection of a particular range of frequency. Tuned circuit and resonant frequency in tuned amplifiersĪs tuned circuits possess the property of resonance. Thus an audio amplifier is not used for radio frequency signal amplification. As it provides a mixture of frequency that lies in the range of 20 Hz to 20 KHz. It is already known that audio amplifiers can amplify high or radio frequency, then what is the need for a radio frequency amplifier?Īn audio amplifier is unable to select a particular frequency signal.
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