Features of transistor amplifier gain

Amplifiers are in use in nearly every area within the field of electronics, the car audio amplifier is still my favorite. Since my first install project at age 10, I was thoroughly intrigued by the art of designing the perfect car audio system. As a fan of the scientific process, I was naturally interested in learning everything I could about the components entailed in an amplifier. After discovering the various amplifier circuits in use in amplifiers, I was even more intrigued about the field of electronics. For me, the components found in electronics were like building blocks, and with enough knowledge and practice, one can construct almost anything.

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Content:

• Transistor amplifier
• US2936424A - Transistor amplifier - Google Patents
• Common Emitter Amplifier Circuit Working & Its Characteristics
• Common Emitter Amplifier and Transistor Amplifiers
• PCB Design & Analysis
• Transistors
• 7.4: Common Collector Amplifier
• US2760007A - Two-stage transistor feedback amplifier - Google Patents

WATCH RELATED VIDEO: Transistor Amplification

Transistor amplifier

Any type of transistor circuit can be designed by using the above mentioned three transistor characteristics. The configuration of the transistors is based on the transistor terminals. There are three types of transistor circuit configuration, these are:. Common Emitter Transistor. Common Base Transistor. Common Collector Transistor emitter follower. Each circuit configuration has a different characteristic curve. Based on the requirement of the circuit, the transistor configuration is chosen accordingly.

Few things are considered while using the correct transistor for the circuit. These are the maximum voltage rating between the emitter and the collector UCEmax , maximum power to build a circuit, and maximum collector current ICEmax. An electric circuit must not exceed these maximum values in order to function properly. Permanent damage to the circuit may occur if it exceeds the value. It is also important to maintain proper current amplification and frequency.

In this kind of configuration, an emitter is used as a common terminal for both input and output. It works as an inverting amplifier circuit. In this case, the input is applied in the region of base-emitter and the output is obtained from between the terminals of collector and emitter. In this case,. V BE is the input voltage,. I B is the input current,. V CE is the output voltage, and. I C is the output current. The common emitter configuration is usually based on transistor-based amplifiers.

Under this condition, the emitter current is equivalent to the sum of base current and collector current. This equation is transistor equations for the CE configuration. The ratio of the collector current to that of emitter current gives current gain alpha in the Common Base configuration. Similarly, the ratio of the collector current to that of base current gives current gain beta in the common-emitter configuration. Relationship Between the Two Current Gains is:.

This configuration uses one of the three circuit configurations. It has average input and output values of impedance. It also has an average current and voltage gains.

Input Characteristics of Transistor. The input characteristic of a transistor is obtained between the inputs current I B and the input voltage V B by having a constant output voltage V CE.

By keeping the output voltage V CE constant and changing the input voltage V BE of different points, we can examine the values of the input current of each of the points. This is the required equation to calculate the input resistance R in. Output Characteristics. The output characteristic of a common emitter is obtained between the output voltage V CE and output current I C at a constant input current I B.

By keeping the base current I B constant and changing the value of output voltage V CE at different points, we can calculate the value of collector I C for each point. Now, if we plot a graph between I C and V CE , we get the output characteristics of a common emitter configuration.

This is the equation to calculate output resistance.

US2936424A - Transistor amplifier - Google Patents

In the design of transistor amplifying circuits, it has been found that conventional cascading of ordinary transistor stages often results in an amplifier having too low a. For example, an amplifier comprising a series of cascaded, common-base stages using transistors having current gains of less than unity may be designed to provide a wide bandwidth, but is ordinarily characterized by low power gain; if the input impedance and output impedance of such an amplifier are equal, its power gain is in fact less than unity. In the usual common-emitter cascaded amplifier, on the other hand, relatively high power gain may be obtained, but the bandwidth is relatively narrower than in the common-base configuration and, particularly for some video amplification purposes, is often entirely inadequate. Furthermore, the technique of varying the value of load impedance in each stage, which is commonly used in vacuum tube circuits to vary the bandwidth, is in general not effective in the type of transistor circuits considered herein, since the bandwidth limitation in the latter case is usually due not to the collector capacitance butlto the alpha-cutoff frequency f of the transistors employed.

Common Emitter Amplifier Circuit Working & Its Characteristics

The common collector amplifier is often referred to as an emitter follower, or more generically, as a voltage follower. The key characteristics of a voltage follower are a high input impedance, a low output impedance and a non-inverting voltage gain of approximately one. The name comes from the fact that output voltage follows the input, that is, it's at the same voltage level and is in phase with the input. While this configuration does not produce voltage gain, it does produce current gain, and therefore, power gain. It's primary purpose is to reduce impedance loading effects, for example, to match a high impedance source to a low impedance load. Consequently, they are used as high-Z input buffer stages or as drivers for low impedance loads such as loudspeakers. 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. Because the collector is at the AC common, there is no need for a collector resistor. Perhaps the best way to think about the follower is not that it gives a voltage gain of one, but that it will prevent signal loss. The derivation for the emitter follower's voltage gain equation is similar to that shown for the common emitter amplifier.

Common Emitter Amplifier and Transistor Amplifiers

In the next three tutorials, including this one, we will present the three elementary topologies of bipolar transistors based amplifiers : the Common Emitter Amplifier , the Common Collector Amplifier and finally, the Common Base Amplifier. The first figure below presents the simplified electrical circuitry of a CEA configuration. The aim of Figure 1 is to purely show the general configuration of a CEA. However, some important elements of a real CEA architecture are missing and will be presented more in detail in the next section.

PCB Design & Analysis

Lozier, Short Hills, N. A principal object of the invention is toexten'd the advantagesof' reduced power consumption and maintenance afiord'ed by the use of transistors tothe'carrier-telephonerepeater amplifier field. A- related object is to produce-a substantial amount of gain in a multistage transistor amplifier over the wide range of frequencies requiredfor carrier telephone operation. While the; overall gain: required from such an amplifier is a function: of both repeater spacing and the gauge of the cable used: for transmission, an insertion gain: of: approximately 20' db at a level of of dbm is a; typical; requirement. Furthermore, the frequency range. Since the impedance level of such system components as cables, filters, and: hybrids is typically of the order of ohms,it is desirable that the input and output impedancesof-an-amplifierintended to be associated with suchelements also be.

Transistors

Any type of transistor circuit can be designed by using the above mentioned three transistor characteristics. The configuration of the transistors is based on the transistor terminals. There are three types of transistor circuit configuration, these are:. Common Emitter Transistor. Common Base Transistor. Common Collector Transistor emitter follower.

7.4: Common Collector Amplifier

When the capacitors are regarded as ac short-circuits, it is seen that the circuit input terminals are the transistor base and emitter, and the output terminals are the collector and the emitter. So, the emitter terminal is common to both input and output, and the circuit configuration is termed common-emitter CE. The current and voltage waveforms for the CE circuit in Fig.

US2760007A - Two-stage transistor feedback amplifier - Google Patents

RELATED VIDEO: Transistor Amplifiers - Class A, AB, B, \u0026 C Circuits

These modes are used in various transistor based applications as per characteristics mentioned below. As we know transistor is solid state equivalent of a triode valve. It is a solid state, current gain device which has 3 terminals. The terminals are collector, base and emitter. It is made by both the p-type and n-type materials.

In common emitter configuration, base is the input terminal, collector is the output terminal and emitter is the common terminal for both input and output. That means the base terminal and common emitter terminal are known as input terminals whereas collector terminal and common emitter terminal are known as output terminals. In common emitter configuration, the emitter terminal is grounded so the common emitter configuration is also known as grounded emitter configuration. Sometimes common emitter configuration is also referred to as CE configuration, common emitter amplifier, or CE amplifier. The common emitter CE configuration is the most widely used transistor configuration. The common emitter CE amplifiers are used when large current gain is needed. The input signal is applied between the base and emitter terminals while the output signal is taken between the collector and emitter terminals.

There are different types of transistor amplifiers operated by using an AC signal input. This is interchanged between the positive value and negative value, hence this is the one way of presenting the common emitter amplifier circuit to function between two peak values. This process is known as the biasing amplifier and it is an important amplifier design to establish the exact operating point of a transistor amplifier which is ready to receive the signals hence it can reduce any distortion to the output signal. In this article, we will discuss common emitter amplifier analysis.