Tuned amplifiers
Download as PPTX, PDF•0 likes•1,844 views
This document discusses tuned amplifiers, including their characteristics, classifications, and circuit types. It describes tuned amplifiers' ability to selectively amplify signals at resonant frequencies. The key circuit types discussed are single tuned, double tuned, and staggered tuned amplifiers. It also covers topics like Q-factor, series and parallel resonance, and stability considerations for tuned amplifier design. The document appears to be from an electronics course, outlining tuned amplifier concepts and circuits.
Tuned amplifiers
- 1. INTERNATIONAL SCHOOL OF TECHNOLOGY & SCIENCES (FOR WOMEN) DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING Prepared By: Mr. K V VENKATARAMANA, Assistant Professor. K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS II BTECH II SEMESTER ELECTRONIC CIRCUIT ANALYSIS UNIT VI
- 2. Contents: Introduction to Tuned Amplifier Q-Factor Small signal tuned amplifier Capacitance single tuned amplifier Double Tuned Amplifier Effect of Cascading single Tuned Amplifier Staggered tuned Amplifiers Stability of Tuned Amplifiers K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 3. DEFINITION:- An amplifier circuit in which the load circuit is a tank circuit such that it can be tuned to pass or amplify selection of a desired frequency or a narrow band of frequencies, is known as Tuned Circuit Amplifier. K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 4. CHARACTERISTICSOFTUNEDAMPLIFIER Tuned amplifier selects and amplifies a single frequency from a mixture of frequencies in any frequency range. A Tuned amplifier employs a tuned circuit. It uses the phenomena of resonance, the tank circuit which is capable of selecting a particular or relative narrow band of frequencies. The centre of this frequency band is the resonant frequency of the tuned circuit . Both types consist of an inductance L and capacitance C with two element connected in series and parallel. K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 5. RESONANCECIRCUITS: •When at particular frequency the inductive reactance became equal to capacitive reactance and the circuit then behaves as purely resistive circuit. This phenomenon is called the resonance and the corresponding frequency is called the resonant frequency. C L Tu ned c ircuit K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 6. Resonance circuits ParallelSeries K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 7. Classification of Tuned Circuits Small signal amplifier, low power, radio frequency Class A Single Tuned circuit(one parallel circuit is employed) Double tuned circuit(two tuned circuit are employed) Staggered Tuned amplifier Large signal amplifier, low power, radio frequency Class B&C Shunt peaked tuned with higher band width K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 8. CLASSIFICATION OF TUNED AMPLIFIER Tuned amplifier Small Signal Amplifier Single Tuned Amplifier Double Tuned Amplifier Stagger Tuned Amplifier Large signal Amplifier K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 9. CLASSIFICATIONOFTUNED AMPLIFIERS Small Signal Tuned Amplifiers :- They are used to amplify the RF signals of small magnitude. They are further classified as: (a)Single Tuned Amplifiers:- In this we use one parallel tuned circuit in each stage. (b)Double Tuned Amplifiers:- In this we use two mutually coupled tuned circuits for every stage both of tuned circuits are tuned at same freq. (c)Stagger Tuned Amplifiers:- It is a multistage amplifier which has one parallel tuned circuit for every stage but tuned frequency for all stages K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 10. (2) Large signal tuned amplifiers:- They are meant for amplifying large signals in which large RF power is involved & distortion level is also higher. But tuned circuit itself eliminates most of the harmonic distortion. K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 11. SERIESRESONANT CIRCUIT •It is the circuit in which all the resistive and reactive components are in series. K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 12. SERIESRESONANT LC K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 13. SERIESRESONANTCIRCUIT: Impedance Of The Circuit: - Z = { R2 + (XL – Xc)2}1/2 Z = { R2 + (ωL – 1/ ωC)2}1/2 For resonant frequency:- (XL = XC ) XL = ωL = XC = 1/ ωC = 2 π frL 1 / 2 π frC K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 14. SERIESRESONANTCIRCUIT Since at resonance, XL = Xc 2 π frL = 1 / 2ПfrC fr = 1 / 2 π √LC ωr fr = 1 / √LC K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 15. RESONANCECURVEOFSERIES RESONANTCIRCUIT: K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 16. QUALITYFACTOR: • It is voltage magnification that circuit produces at resonance is called the Q factor. Imax XL / Imin R• Voltage Magnification = = XL/ R • At Resonance = XL/R = XC/R ωrL / R = 1 / ωrRC K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 17. THUS Qr = ωrL / R = 1/ ωrC R = 2 π fr L / R = (2 π L / R) * (1 / 2 π √LC ) = √(L/C) / R = { tan Ф = power factor of coil } tanФ K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 18. IMPORTANTPOINTS (1) Net reactance , X = 0. (2) Impedance Z = R . (3) Power factor is unity. (4) Power expended = 6 watt. • • Current is so large & will produce large voltage across inductance & capacitance will be equal in magnitude but opposite in phase. Series resonance is called an acceptor circuit because such a circuit accepts current at one particular frequency but rejects current at other frequencies these circuit are used in Radio – receivers . K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 19. REACTANCECURVESERIESRESONANT CIRCUIT XL = 2ΠfL X = XL - XC XC = 1 2ΠfC R fr K V VENKATARAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 20. PARALLELORCURRENTRESONANCE K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 21. PARALLELORCURRENTRESONANCE •When an inductive reactance and a capacitance are connected in parallel condition may reach under which current resonance (also known as parallel or anti- resonance ) will take palace. •The frequency at which this happened is known as resonant frequency. Current will be in resonance I reactive component of R - L branch. •IR-L sinФ R-L = Reactive component of capacitive branch, neglecting leakage reactance of capacitor C. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 22. FREQUENCY V/S IMPEDANCE CURVE FOR LCR CIRCUIT K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 23. Inductance Quality factor (Q) 24 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 24. RESONANTRESONANCE CURVE OF PARALLEL CIRCUIT : With low resistance With high resistance current fR K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 25. 25
- 26. 26 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 27. 27
- 28. 92
- 29. 29 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 30. C o n d u c tan ce(R ) 30 Q t eff Susp tan ce(L / C )
- 31. SINGLETUNEDAMPLIFIER USINGFET K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 32. LIMITATION: • This tuned amplifier are required to be highly selective. But high selectivity required a tuned circuit with a high Q- factor . • A high Q- factor circuit will give a high Av but at the same time , it will give much reduced band with because bandwidth is inversely proportional to the Q- factor . • It means that tuned amplifier with reduce bandwidth may not be able to amplify equally the complete band of signals & result is poor reproduction . This is called potential instability in tuned amplifier. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 33. Double tuned Amplifier: K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 34. 34 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 35. 35
- 36. 36 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 37. 37 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 38. 38 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 39. 39
- 40. 40
- 41. 41 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 42. STAGGERTUNEDAMPLIFIERS: K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 43. 43
- 44. 44 K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 49. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 50. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 51. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 52. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 53. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 54. Video Amplifiers (IC MC1550) K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 55. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 56. APPLICATIONS OF TUNED AMPLIFIER Tuned amplifiers serve the best for two purposes: a) Selection of desired frequency. b) Amplifying the signal to a desired level. USED IN: Communication transmitters and receivers. In filter design :--Band Pass, low pass, High pass and band reject filter design. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 57. ADVANTAGES It provides high selectivity. It has small collector voltage. Power loss is also less. Signal to noise ratio of O/P is good. They are well suited for radio transmitters and receivers . K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 58. DISADVANTAGES They are not suitable to amplify audio frequencies. If the band of frequency is increase then design becomes complex. Since they use inductors and capacitors as tuning elements, the circuit is bulky and costly. K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS
- 59. Thank you K V VENKATA RAMANA‖ ECA ‖ Dept of ECE ‖ ISTS