Class a amplifier experiment. 4 INTRODUCTION is a compact, ready to use Class A Amplifier experiment board. Experiment Questions: The maximum efficiency of Class-B/AB power amplifier is 79%. 4-3. Oct 28, 2020 · Abstract and Figures. Introduction: The power amplifier is said to be Class A amplifier if the Q point and the input signal are selected such that the output signal is obtained for a full input signal cycle. CLASS A AMPLIFIER REPORT by Tan keng hian on Prezi. (I link once more to Dave Hunter’s excellent short article on the topic, since he explains the distinction so much better than I can. In this paper, a new approach to class-A power amplifier design is proposed. By looking at the schematic, the first stage using 2SK170 as source follower, much like a buffer stage , and directly feed into IRFP240, operate as a class A single ended amplifier with another IRFP240 as constant current source. The notable changes are the inclusion of an input signal voltage, Vin, and a load, RL. AudioAcademy. 4 Class A Amplifier Operation GROUP MEMBERS: OESMER, ANDREA PANES, MICHAELA ANGELICA TEPORA, NOEL DARREN ECE32 DATE SUBMITTED: OCT 21, 2020 I. 2 Experiment No. : 08 Name of the experiment: Study of Class A power amplifier circuit using BJT. Resistors: 47kΩ, 10kΩ, 4. R1 and R2 are meant for biasing the transistors. Trainer kit 1 2. “In practice, this efficiency cannot be obtained because of other losses in the circuit (pg. Experiment 7 To study the operation of Class A Amplifier. Calculate the voltage gain of the CE amplifier. Physical size is low for a given power o/p. Explore their applications in audio systems, car audio, home theater systems, and portable devices. Application: Efficiency = ouput/input. The advantages of class c amplifier include. T1 is. 7kΩ, (2) 1kΩ, 680Ω, 150Ω 2. The detail of whole design had been explained in FirstWatt page. To control the high load current. I (C) = I (B) × DC current gain. List of Accessories with 12 3. Background Class A Stage The amplifier given in Fig. 6. No. May 31, 2024. Objective. Thus the operating point is selected in such a way that the transistor operates only over the linear region of its load line. Visan. 2 2 V N I. Nov 30, 2022 · The process of using analog power amplifiers to amplify analog signal, such as Class A, Class B, and Class AB amplifiers. May 5, 2022 · 6) 5 Watt Class A Amplifier Circuit. Class B: – The amplifiers two output transistors only conduct for one-half, that is, 180 o of the input waveform. 1 – Analysis of Wave forms for Different Classes of Amplifiers. Aarthi,AP (SG) 2. Q1 and Q2 are two identical transistor and their emitter terminals are connected together. The circuit arrangement of the Class B push pull amplifier is similar to the Class A push pull amplifier except for the absence of the biasing resistors. max. CLASS -A POWER AMPLIFIER(TRANSFORMER COUPLED) AIM: To o b ser ve the input and outp u t w avef or ms and to calculate the eff iciency. 2kΩ and a supply voltage of 12v. Class A amplifier • It is similar to the CE Amp we have studied. Particulars Specification/Range Quantity Make/Model No. Most audio “power” amplifiers use a class B configuration, where one transistor provides power to the load during one-half of the waveform cycle (it pushes) and a second transistor provides power to the load for the other half of the cycle (it pulls ). It is represented by the symbol shown in Fig. Class A power amplifier is one in which the output current flows during the entire cycle of input signal. #PowerAmplifiers #ECA #VivtronicsTopics Discussed in the video:0:00 Introduction to Power Amplifiers 0:50 Power Amplifier Definition 2:56 Features of Power Jun 14, 2022 · A common collector amplifier is constructed using an NPN bipolar transistor and a voltage divider biasing network. Q-Point of a single stage CE class A-Amplifier. Apr 27, 2020 · Class B Complementary symmetry amplifier with cross over distortion . It creates a lot of RF interference. The purpose of the class A bias is to make the amplifier relatively free from noise by making the signal waveform out of the region between 0v to 0. From Figure 5, we can see that the Output/Input characteristic of a Class B push-pull configuration is only partially linear. Linearity is low. Indeed, in a class B amplifier. volts Fig. It abbreviated as (Op Amp). 1. Determine the compliance and maximum load power for class A amplifier circuits. Copy of CLASS A Power Amplifier. Class C amplifier uses less than 180-degree conduction angle. Also find the value of the Emitter resistor, RE if it has a voltage drop of 1v across it. Experiment 17 Class A Power Amplifier When Class-B amplifiers amplify the signal with two active devices, each operates over one half of the cycle. 2. Class A amplifier are power amplifier that are used to deliver high values of power to low resistance. Class B has a maximum theoretical efficiency of π/4 (≈ 78. The Q point Aug 14, 2011 · A class D amp shoves an analog signal through a digital circuit and into an analog low-pass to produce an analog signal. 3. Nov 8, 2012 · The recent experience making a DIY Class A Champ reignites for me the eternal debate between the merits of Class A and Class A/B amps. Calculate the maximum Collector current ( Ic) flowing through the load resistor when the transistor is switched fully “ON” (saturation), assume Vce = 0. The resistance of the transformer windings is normally very small, so that there is no effect on the transistor bias conditions. The larger the value of VCE (max) and the smaller the value of VCE (min) ,the closer the Basic design process. This experiment seeks to investigate; 1. If the input is a sinusoidal, then the output is also sinusoidal over the DC biasing voltage (Fig. Class A. 5%). Since the primary of the transformer has negligible dc resistance, there is negligible dc power lost at this point. This fact is illustrated in the Figure 1 below : fig 1 : Operating zone of class C amplifiers. May 22, 2022 · A common collector amplifier using two-supply emitter bias is shown in Figure 7. : 399070389 INSTRUCTOR: Dr. Determine AC load lines for class A amplifier stages. ) Like most American players of a certain age, I grew up without access to EXPERIMENT No. Datasheet 9 5. Objectives: After completing this experiment, you should be able to, 1. While other biasing networks are possible for a Class A amplifier circuit, some type of DC bias voltage is necessary to make a bipolar junction transistor operate in Class A mode. • It conducts for the entire signal cycle and consequently has the lowest efficiency. With a CE amplifier, MPP is the smaller of led cor 2Vao Some of the With a CE amplifier, MPP is the smaller of led cor 2Vao Some of the important quantities in a Class-A amplifier are the current drain, the maximum transistor power dissipation, the maximum unclipped load power, and the stage efficiency In this experiment, the voltages, currents, and powers of a Class-A amplifier will be calcu- lated and measured. Farouq Altawil DATE: 9/12/2001 Purpose The purpose of this experiment is to demonstrate the operation of class A common emitter power amplifier. Maximum 80% efficiency can be achieved in radio frequency related operations. Class A amplifier configuration is the simplest of all the power amplifier configuration because there is no switch off distortion to the output waveform even during the negative half of the cycle. efficiency (%) = 50 [ (VCE (max)-VCE (min))/ (VCE (max)+VCE (min))]^(2) %. class b complementary symmetry amplifier. How to create and deliver a winning team presentation. To verify that the amplifier Q-point and gain are close to their designed values. Based on the signals obtained using the amplifier, the efficiency can be expressed as. Single Class AB amplifiers can be combined to form push-pull Class AB amplifiers. Output = 50 W. 5 CLASS A POWER AMPLIFIER I. A Class-A amplifier is one in which both output stages of the device are constantly on at full power. Micatronics Engineering UNI. We have read about the configurations in which the transistor can be connected; namely CB, CC, and CE, the biasing of the E-B and B-C junction, and the regions of operations; namely cutoff, the active region, and the saturation region. 3. Efficiency = 50 *{ [V ce max – V ce min]/ [V ce max + V ce min]} % EXPERIMENT NO. Components needed: 1. 331). Report comment Nov 21, 2021 · With a CE amplifier, MPP is the smaller of led cor 2Vao Some of the important quantities in a Class-A amplifier are the current drain, the maximum transistor power dissipation, the maximum unclipped load power, and the stage efficiency In this experiment, the voltages, currents, and powers of a Class-A amplifier will be calcu- lated and measured. The Class B amplifier circuit above uses complimentary transistors for each half of the waveform and while Class B amplifiers have a much high gain than the Class A types, one of the main disadvantages of class B type push-pull amplifiers is that they suffer from an effect known commonly as Crossover Distortion. Describe the operation of a dynamic loudspeaker. Class A: amplifier that is at least nominally linear for small to moderate-amplitude input signals. Creator Nov 16, 2022 · Class-B power Amplifier Experiment no. We have specially described enhanced NMOS structures that allow a current to pass when the command or gate voltage is positive and above a certain threshold value. Notes: Discuss with your students the meaning of “Class A” amplification, and why DC biasing is necessary in order to achieve this mode of operation in a BJT circuit. The input is coupled into the base like the common emitter amplifier, however, the output signal is taken at the emitter instead of at the collector. Calculate the maximum output power and efficiency. Blog. EMT 1255L The Common-Emitter Amplifier Jose Ynfante & Mariane Gil-Perez 10/25/ Lab report #7 exp 8 Section-D Objective: The objective of this laboratory experiment is to build a common emitter amplifier circuit and measure the dc and ac parameters, ac resistance, the ac input resistance, and the voltage gain, and see the differences between thee input and output signals. The common-emitter stage, however, suffers from the Miller effect, which produces a reduction in amplifier bandwidth as the amplifier voltage gain Apr 22, 2024 · A common emitter amplifier circuit has a load resistance, RL of 1. Apr 21, 2024 · This Class A amplifier design offers a versatile solution with adjustable quiescent current, efficient common emitter configuration, and strategic use of components like capacitors for stability. Minimum input required = Output/maximum efficiency = 50/0. They are called large signal amplifiers. The circuit diagram of a typical Class A push pull amplifier is shown above. This results in a maximum efficiency of around 19%, which is lower than 1/3 of the efficiency of typical Class B configurations. This Transformer Coupled Class A Power Amplifier arrangement enhances the conversion efficiency by a factor of 2 by eliminating the dc power dissipation in the load. This signal is generally small and needs to be amplified sufficiently to operate an output device. If R 1 = 5k6Ω, R 2 = 6k8Ω and the supply voltage is 12 volts. Determine the DC input voltage to bias the BJT in the center of the linear region. The analysis of the low-frequency response is done by considering each capacitor's discharge path and forming an equivalent Dec 11, 2023 · December 11, 2023 by Rachel Hansen. Efficiency is much improved over class-A amplifiers. 5 % efficiency and a 180 1. ECA Lab manual. The efficiency of a transformer-coupled class A power amplifier can be given as. 2, the configurations of class-A, B, and C amplifiers can be either a push–pull or a single ended tuned version. 2- Measuring output signal and amplifier efficiency and comparing measured results with theoretical values. By understanding the formulas and construction details, enthusiasts can experiment with variations to meet specific audio amplification needs. 1 is of type called Class A amplifier. Calculations in a Class A Amplifier. 7kΩ, 680Ω, 150Ω 2. It operates in a linear portion of its characteristic; it is equivalent to a current source. simulation of class a power amplifier using multisim. Essentially, it consists of several transistor amplifiers. The cascode amplifier is comprised of a common-emitter input stage and a common base output stage. It is difficult to obtain coupling transformers and ideal inductors. Maximum current I. In class A operation, the entire input It is a class A amplifier. 1 Name Date Class Experiment 10 Amplifier Frequency Response In a typical transistor amplifier, the low-frequency response is determined by the coupling and bypass capacitors. 6v where the transistor’s input characteristic is non-linear. Procedure 1. For a given input signal, a larger Rc means. Learn about the definition and working principle of Class D amplifiers, their advantages like higher efficiency and compact size, as well as disadvantages such as distortion and limited frequency response. The amplifier uses both digital as well as analog portions. multimeter 1 4. Electrical Engineering questions and answers. current shunt feedback amplifier. Aug 11, 2018 · A push pull amplifier can be made in Class A, Class B, Class AB or Class C configurations. 4. • As the signal swings from its positive to negative, peak to peak Apr 29, 2015 · THD's BiValve is the ultimate modern Class A amp. Transistor as a device - Switch and Amplifier. Calculate the values of: V B, V C and V E, the emitter current I E, the internal emitter resistance r’ e and the amplifiers voltage gain A V when a load resistance Experiment 1: Class – A Power Amplifier Objectives: After completing this experiment, you should be able to, 1. This class A amplifier circuit produces 5 watts rms into an 8 ohm load, however it needs a supply of 22 to 24 volts at 1 amp. OBJECTIVES To calculate and measure DC and AC voltages, and power input and output for class A power amplifier II. Mar 2, 2024 · The maximum efficiency of a class A amplifier is 50%; The maximum efficiency of a class B amplifier is 78. 0. CLASS A Power Amplifier. How class A-Amplifier can be used for clipping of large signals 4. Mar 22, 2021 · After completing this chapter, you should be able to: Define class A operation. Class A amplifiers are the most linear design with May 22, 2022 · To verify the basic operation of a class B amplifier, the circuit of Figure \(\PageIndex{13}\) is entered into a simulator. 5. 2. The examples presented in Part 2 are single band HF and VHF amplifiers at the 5 W level — a par-ticularly enjoyable and educational class of amplifiers for the experimenter. This amplifier is based on a two-supply emitter bias circuit. IC3 vout Q 3 IC2 RL v in +10 v C rp v g vm be be RL vout v in E B C Figure 2: The common-emitter amplifier with bias network replaced by an ideal current source, and the corresponding small-signal model. 4-2. Introduction to Class C Amplifier. Common Emitter Amplifier. The function of R. As shown in figures. In order to demonstrate the effectiveness of the proposed design technique, a practical example of class-A power amplifier Dec 8, 2018 · It’s a low distortion type amplifier having very low efficiency but high gain. 2 and so produce an undistorted and amplified Question: Experiment 28 Experiment Class-A Amplifiers In a Class-A amplifier, the transistor operates in the active region throughout the ac cycle. pdf), Text File (. 2 AIM:-Applications of Op-amp -Op-amp as summing amplifiers, Difference amplifier, Integrator and differentiator. Used in RF applications. Since this operating zone extends beyond the class B operating point, which represents a 78. This is useful for students to understand the working and operation of various Voltage amplifier categories. Class G uses multiple power supply rails of various voltages and automatically switches between these supply rails as the input signal changes. ” What is the advantage of Class-B/AB power amplifier? An advantage of class B/AB amplifiers over class A is a much EXPERIMENT 6 Power Amplifiers A. • The Q-point is in the middle of the load line (VCEQ = VCC/2). Single ended amplification only comes in pure Class A, and is the least efficient form of power stage you can reasonably create, typically idling between three and five times the rated output power. 2 The useful AC power is then v O (t), volts V CQ T t V CQ +V CP V CQ-V CP v S + v O - R 2 R 1 R L V Electrical Engineering questions and answers. Class-B amplifiers are also favoured in battery-operated devices, such as transistor radios. Determine the small-signal (AC) gain of the amplifier at the operating point above. class a power amplifier. In the first section, types of power amplifiers have Most modern audio amplifiers have a flat frequency response as shown above over the whole audio range of frequencies from 20 Hz to 20 kHz. This two part article describes a proce- dure to design and build a simple tran-sistor linear amplifier. A class C amplifier is bias for operation for less than 180° of the input signal cycle and its value is 80° to 120°. Because the collector is at the AC common, there is no need for a collector resistor. I have a look at how it works, how it behaves and what are some things to keep in mind About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright For those who might be unfamiliar with or new to breadboarding, in this video we go through the process of assembling a simple Class-A transistor amplifier o Class A Circuit – Instead of capacitor coupling, a Transformer Coupled Class A Amplifier may be used to ac couple amplifier stages while providing dc isolation between stages. txt) or read online for free. Class A Power Amplifiers Prof. Since the early 1980s, many researchers have worked on the development of different types of digital amplifiers that directly perform power amplification from digital speech data without the need for analog conversion. 7. Its design consists of two power tubes working independently in parallel, combined through a custom output transformer. Explain the advantages and disadvantages of using localized feedback (swamping). To design, build, and test a CE amplifier, using a 2N3904 NPN transistor, with a loaded voltage gain of -5 and input resistance of at least 1 KΩ that is capable of driving an AC-coupled 1 KΩ load with a 2 VP-P sine wave. This is equivalent to saying the signal does not drive the transistor into either satura- tion or cutoff on the ac load line. To understand the operation of a Class A amplifier. After completing this chapter, you should be able to: Determine the voltage gain, input impedance and output impedance of simple BJT amplifiers. Not fit in audio applications. Connecting wires 3. 4 EE382 1 Experiment no. Jan 23, 2022 · #147 In this video I look at the basics behind the Class C amplifier. Obtain the transfer function of the amplifier. Transformerless Output Stage. AloyOng. Nov 4, 2023 · Class A: – The amplifiers single output transistor conducts for the full 360 o of the cycle of the input waveform. The relationship between the primary and secondary values of voltage, current and impedance are summarized as: 1 V 1 N . Simulate in PSpice the CE amplifier in Fig. Resistors: 47kΩ, 22kΩ, (2) 10kΩ, 4. Question: 25 PUSH-PULL POWER AMPLIFIER Objective: The objective of this ive of this experiment is to design, build, and test class B and class AB pusa wwer amplifiers for given specifications and observe the performances of the two pull power ampli classes Prelab: Design a class B and on a class B and class AB push-pull power amplifier whose circuit diagram is shown Only one linear circuit topology delivers the appropriate characteristic, and that is the single- ended amplifier. Figure \(\PageIndex{13}\): Class B amplifier in simulator. To construct a Class A amplifier using breadboard. Determine the efficiency and required device ratings for class A amplifier circuits. The Efficiency of class A-Amplifier 3. So, while the Class A amplifier can do an excellent job of producing linear amplification, it is very inefficient. G. 1 and 2. 1 Class A The class-A amplifier has the highest linearity over the other classes. Mar 20, 2021 · This particular circuit is called a “class B,” push-pull circuit. For all values of input Experiment 28 Experiment Class-A Amplifiers In a Class-A amplifier, the transistor operates in the active region throughout the ac cycle. The MOSFET is an active component that consists of a conductive channel encapsulated between a semiconductor substrate and a metal/oxide structure. Observe the Class - A Power amplifier output waveform. Efficiency is high. Large signal amplifiers have large voltage swing and current swing and the signal power handled by such amplifiers remain large. The ac power is, however, coupled magnetically across the With a CE amplifier, MPP is the smaller of led cor 2Vao Some of the important quantities in a Class-A amplifier are the current drain, the maximum transistor power dissipation, the maximum unclipped load power, and the stage efficiency In this experiment, the voltages, currents, and powers of a Class-A amplifier will be calcu- lated and measured. Voltage amplifiers come under small signal amplifiers. 5 Electronics lab. single tuned voltage amplifier. Class B amplifiers produce significant crossover distortion, which is highly undesirable. Also, \(A_v\) should be about 1. Based on biasing mode, Amplifier can be classified as Class A, Class B, Class AB, and Class C Amplifier. (1). voltage series feed Name: Kaushik Mazumder Roll:1901026 Section: A Expt. 2). Experiment No: 01 Name of the experiment: Study of Class A Power Amplifier. Input Impedance, ZIN or Input Resistance as it is often called, is an important parameter in the design of a transistor amplifier and as such allows amplifiers to be characterized according to their effective input and output impedances as well as their power and current ratings. This clever arrangement allows the BiValve to operate purely in Class A at all times with a comparatively hefty output of up to 30 watts. These amplifiers have an output greater than 1 W and resistance from 4 ohm to 300 ohms. It is about 30%. In this lecture, we will discuss amplifiers with improved efficiency. Transistor: (1) 2N3904 3. Warranty 11 6. The efficiency of Class C amplifier is much more than the A, B, and AB. With a CE amplifier, MPP is the smaller of led cor 2Vao Some of the important Feb 5, 2020 · simulation of class a power amplifier using multisim. CRO 1 THEORY: (1 ) SUMMING AMPLIFIER: The summing circuit using Op-amp as EXP17 Class a Power Amplifier - Free download as PDF File (. So this amplifier can amplify input list of experiments a) testing in the hardware laboratory: . (series fed) 4. This module shows how to simply calculate the values needed to make a working amplifier that has correct class A bias as described in Amplifier Module 1. Dec 11, 2018 · Class C amplifier is tuned amplifier which works in two different operating modes, tuned or untuned. 1. Such a technique, which is mostly based on low-frequency characterisation, allows to reach the same design goals obtained through expensive nonlinear setups operating at microwave frequencies. Oct 1, 2017 · 1. hartely oscillator 8. Theory: An amplifier receives a signal from some pickup transducer or other input source. Frequency points ƒL and ƒH relate to the lower corner If we consider an amplifier with power gain A P and voltage gain A V, the power and voltage gain in dB are defined by : eq 1 : Power and voltage gain in dB While the gains in linear scale are always positive (A P ,A V ≥0), their equivalent in dB can either be positive if an amplification is being realized (A P ,A V >1) or negative if the A transformer-coupled class-A amplifier uses a transformer to couple the output signal from the amplifier to the load. Oct 18, 2011 · Thus for a transformer-coupled class A power amplifier the maximum theoretical efficiency is 50%. We also know that the transistor when used in the cutoff or May 23, 2014 · For a transformer coupled class A amplifier, the maximum theoretical efficiency goes up to 50%. Class AB: – The amplifiers two output transistors conduct somewhere between 180 o and 360 o of the input waveform. BASIC CONCEPT A class A amplifier draws the same power from a voltage supply regardless of the signal applied. Fig. 1 shows a class A common emitter amplifier, but without its component values. List of Service Centers 11 7. The amplifier should clip just below the \(\pm\)10 volt power rails so a 10 volt peak source is used to verify this. Class G Amplifier – Class G offers enhancements to the basic class AB amplifier design. 5. Figure shows Fig. Class B Power Amplifier - When the collector current flows only during the positive half cycle of the input signal, the power amplifier is known as class B power amplifier. An ideal amplifier would deliver 100% efficiency, but it is not possible practically. 1 7. 4 Class-B Power Amplifier Objectives: 1- Testing of class-B push-pull amplifier. Class A power amplifier. Figure 1––The common-emitter amplifier. To experiment Class-C Tuned Power Amplifier here need some equipments like, Oscilloscope, Power supply, Multimeter, Transistor, Capacitors, Resistors and Signal generator. Clearly clips (limits) for large output voltages. As the collector current changes in response to an input signal, the circuit’s output voltage is developed across the col-lector resistor, Rc. 4. rc phase shift oscillator using transistors. user-172678. A small amount of bias can be added to a Class B amplifier to form a Class AB amplifier, which has considerably less crossover distortion than a Class B amplifier. As we have seen for class AB amplifiers, class C are not defined by a single operating point but rather an operating zone. . During a Class C amplifier operation, the collector flows for less than half cycle of AC signal. 5 = 100 W Depending on their operation, power amplifiers can be grouped into four main classes: - CLASS A operation - CLASS AB operation - CLASS B operation - CLASS C operation The output signal as result of a sinusoidal input signal for each of the four classes can show in Fig. Minimum voltage V. Objectives: 1. The maximum efficiency = 50% = 0. Dept of ECE, Lendi Institute of Engineering and Technology Page 29. Experiment No. EQUIPMENT REQUIRED: S no. larger output voltage change––a higher voltage gain (Av). The common-emitter stage provides high input resistance, which is desirable for voltage amplifiers. Power amplifiers are one in which the output power of the signal is increased. EXPERIMENT 7 THE CLASS A COMMON EMITTER POWER AMPLIFIER NAME: Abdulrahman Ghaleb Mohammad Moh. Repeat step 2 for the emitter follower in Fig. The disadvantages of class c amplifier include. Maximum voltage V. In practice, the efficiency of such an amplifier is somewhat less than 50%. min. two stage rc coupled amplifier. 5%; The maximum efficiency of a class C amplifier is 90%. Class A amplifier design produces a good linear amplifier, but most of the power produced by the amplifier goes wastage in the form of Mar 5, 2020 · The function of power amplifier is to raise the power level of input signal. The main objective of this study is to investigate common power amplifier classes which are class A, B, AB, C and etc. So that these components do not alter the bias, we isolate the input and load through the use of coupling capacitors Cin and Cout. This range of frequencies, for an audio amplifier is called its Bandwidth, (BW) and is primarily determined by the frequency response of the circuit. Detail the functional differences between voltage amplifiers and voltage followers. Theory 6 3. 8. Analog Electronics lab (EC 492)4th sem ECE Mar 22, 2021 · Mohawk Valley Community College. OP AMP THEORY The operational amplifier is a high gain high performance direct-coupled amplifier, which uses feedback to control its performance characteristics. Jan 19, 2019 · DIY Amp Camp Amp ACA PCB. May 22, 2022 · Figure 7. Components needed: Instruments used: 1. At first, the input voltage level Class-F amplifiers are capable of high efficiencies of more than 90% if infinite harmonic tuning is used. 1: Common emitter amplifier using two-supply emitter bias. When there’s a cut-off in the transistor, the Collector-Emitter region behaves as open while in case of saturation the same Collector-Emitter region behaves as short. Because both stages are constantly on, Class A is considered to be the least efficient of power amplifier designs, with an average efficiency of about 20% (50% at best, theoretically). The transistor is always turned ON so that the output current flows for the entire cycle of the input waveform. jq iu sa eg ip li ie cu wi wm