|
Differential Amplifier
A differential amplifier is a type of electronic amplifier that amplifies the difference between two input voltages but suppresses any voltage common to the two inputs. It is an analog circuit with two inputs V_\text^- and V_\text^+ and one output V_\text, in which the output is ideally proportional to the difference between the two voltages: : V_\text = A(V_\text^+ - V_\text^-), where A is the gain of the amplifier. Single amplifiers are usually implemented by either adding the appropriate feedback resistors to a standard op-amp, or with a dedicated integrated circuit containing internal feedback resistors. It is also a common sub-component of larger integrated circuits handling analog signals. Theory The output of an ideal differential amplifier is given by : V_\text = A_\text(V_\text^+ - V_\text^-), where V_\text^+ and V_\text^- are the input voltages, and A_\text is the differential gain. In practice, however, the gain is not quite equal for the two inputs. This means ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Op-amp Symbol
An operational amplifier (often op amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op amp produces an output potential (relative to circuit ground) that is typically 100,000 times larger than the potential difference between its input terminals. The operational amplifier traces its origin and name to analog computers, where they were used to perform mathematical operations in linear, non-linear, and frequency-dependent circuits. The popularity of the op amp as a building block in analog circuits is due to its versatility. By using negative feedback, the characteristics of an op-amp circuit, its gain, input and output impedance, bandwidth etc. are determined by external components and have little dependence on temperature coefficients or engineering tolerance in the op amp itself. Op amps are used widely in electronic devices today, including a vast array of consumer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Emitter
In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. It offers high current gain (typically 200), medium input resistance and a high output resistance. The output of a common emitter amplifier is 180 degrees out of phase to the input signal. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is ''common'' to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous FET circuit is the common-source amplifier, and the analogous tube circuit is the common-cathode amplifier. Emitter degeneration Common-emitter amplifiers give the amplifier an inverted output and can have a very high gain that may vary widely from one transistor to the next. The gain is a strong function of both temperature and bias current, and so the actual gain is somewhat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Tailed Pair
A differential amplifier is a type of electronic amplifier that amplifies the difference between two input voltages but suppresses any voltage common to the two inputs. It is an analog circuit with two inputs V_\text^- and V_\text^+ and one output V_\text, in which the output is ideally Proportionality (mathematics), proportional to the difference between the two voltages: : V_\text = A(V_\text^+ - V_\text^-), where A is the Gain (electronics), gain of the amplifier. Single amplifiers are usually implemented by either adding the appropriate feedback resistors to a standard Operational amplifier, op-amp, or with a dedicated integrated circuit containing internal feedback resistors. It is also a common sub-component of larger integrated circuits handling analog signals. Theory The output of an ideal differential amplifier is given by : V_\text = A_\text(V_\text^+ - V_\text^-), where V_\text^+ and V_\text^- are the input voltages, and A_\text is the differential gain. In pract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breakdown Voltage
The breakdown voltage of an insulator is the minimum voltage that causes a portion of an insulator to experience electrical breakdown and become electrically conductive. For diodes, the breakdown voltage is the minimum reverse voltage that makes the diode conduct appreciably in reverse. Some devices (such as TRIACs) also have a ''forward breakdown voltage''. Electrical breakdown Materials are often classified as conductors or insulators based on their resistivity. A conductor is a substance which contains many mobile charged particles called charge carriers which are free to move about inside the material. An electric field is created across a piece of the material by applying a voltage difference between electrical contacts on different sides of the material. The force of the field causes the charge carriers within the material to move, creating an electric current from the positive contact to the negative contact. For example, in metals one or more of the negatively cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emitter-coupled Logic
In electronics, emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar transistor logic family. ECL uses an overdriven bipolar junction transistor (BJT) differential amplifier with single-ended input and limited emitter current to avoid the saturated (fully on) region of operation and its slow turn-off behavior. As the current is steered between two legs of an emitter-coupled pair, ECL is sometimes called ''current-steering logic'' (CSL), ''current-mode logic'' (CML) or ''current-switch emitter-follower'' (CSEF) logic. In ECL, the transistors are never in saturation, the input and output voltages have a small swing (0.8 V), the input impedance is high and the output impedance is low. As a result, the transistors change states quickly, gate delays are low, and the fanout capability is high. In addition, the essentially constant current draw of the differential amplifiers minimises delays and glitches due to supply-line inductance and capacitance, and the complement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common-emitter
In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. It offers high current gain (typically 200), medium input resistance and a high output resistance. The output of a common emitter amplifier is 180 degrees out of phase to the input signal. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is ''common'' to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous FET circuit is the common-source amplifier, and the analogous tube circuit is the common-cathode amplifier. Emitter degeneration Common-emitter amplifiers give the amplifier an inverted output and can have a very high gain that may vary widely from one transistor to the next. The gain is a strong function of both temperature and bias current, and so the actual gain is somewhat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Collector
In electronics, a common collector amplifier (also known as an emitter follower) is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a voltage buffer. In this circuit the base terminal of the transistor serves as the input, the emitter is the output, and the collector is ''common'' to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous field-effect transistor circuit is the common drain amplifier and the analogous tube circuit is the cathode follower. Basic circuit The circuit can be explained by viewing the transistor as being under the control of negative feedback. From this viewpoint, a common-collector stage (Fig. 1) is an amplifier with full series negative feedback. In this configuration (Fig. 2 with β = 1), the entire output voltage ''V''out is placed contrary and in series with the input voltage ''V''in. Thus the two voltages are subtracted according ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Ground
In electronics, a virtual ground (or virtual earth) is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence. The virtual ground concept aids circuit analysis in operational amplifier and other circuits and provides useful practical circuit effects that would be difficult to achieve in other ways. In circuit theory, a node may have any value of current or voltage but physical implementations of a virtual ground will have limitations of current handling ability and a non-zero impedance which may have practical side effects. Construction A voltage divider, using two resistors, can be used to create a virtual ground node. If two voltage sources are connected in series with two resistors, it can be shown that the midpoint becomes a virtual groun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Transistor Biasing
Bipolar transistors must be properly biased to operate correctly. In circuits made with individual devices (discrete circuits), biasing networks consisting of resistors are commonly employed. Much more elaborate biasing arrangements are used in integrated circuits, for example, bandgap voltage references and current mirrors. The voltage divider configuration achieves the correct voltages by the use of resistors in certain patterns. By selecting the proper resistor values, stable current levels can be achieved that vary only little over temperature and with transistor properties such as β. The operating point of a device, also known as ''bias point'', ''quiescent point'', or ''Q-point'', is the point on the output characteristics that shows the DC collector–emitter voltage (''V''ce) and the collector current (''I''c) with no input signal applied. Bias circuit requirements The bias circuit stabilizes the operating point of the transistor for variations in transistor charact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miller Effect
In electronics, the Miller effect accounts for the increase in the equivalent input capacitance of an inverting voltage amplifier due to amplification of the effect of capacitance between the input and output terminals. The virtually increased input capacitance due to the Miller effect is given by :C_=C (1+A_v)\, where -A_v is the voltage gain of the inverting amplifier (A_v positive) and C is the feedback capacitance. Although the term ''Miller effect'' normally refers to capacitance, any impedance connected between the input and another node exhibiting gain can modify the amplifier input impedance via this effect. These properties of the Miller effect are generalized in the Miller theorem. The Miller capacitance due to parasitic capacitance between the output and input of active devices like transistors and vacuum tubes is a major factor limiting their gain at high frequencies. Miller capacitance was identified in 1920 in triode vacuum tubes by John Milton Miller. History The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Figure 3
Figure may refer to: General *A shape, drawing, depiction, or geometric configuration * Figure (wood), wood appearance *Figure (music), distinguished from musical motif *Noise figure, in telecommunication * Dance figure, an elementary dance pattern *A person's figure, human physical appearance Arts *Figurine, a miniature statuette representation of a creature *Action figure, a posable jointed solid plastic character figurine *Figure painting, realistic representation, especially of the human form *Figure drawing * Model figure, a scale model of a creature Writing *figure, in writing, a type of floating block (text, table, or graphic separate from the main text) *Figure of speech, also called a rhetorical figure *Christ figure, a type of character * in typesetting, text figures and lining figures Accounting *Figure, a synonym for number *Significant figures in a decimal number Science *Figure of the Earth, the size and shape of the Earth in geodesy Sports *Figure (horse), a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Splitter
A phase splitter is a device that separates a signal into multiple phases (or polarities). The term is most often applied to amplifiers that produce two "balanced" voltage outputs: of equal amplitude but opposite polarity (i.e. 180 degrees phase difference), but sometimes is used to refer to the generation of quadrature signals (i.e. differing by 90 degrees). The term is not used for logic circuits producing complementary outputs, nor applied to differential amplifiers that have balanced inputs ''and'' outputs. Methods * using a unity gain inverting amplifier to provide an inverted copy of its input signal; * a split-load amplifier (also known as a "cathodyne" or "concertina phase splitter", especially in the context of vacuum tube implementations); a transistor implementation is shown in the diagram; * a differential pair amplifier can form a phase splitter in two ways: ** if the shared emitter (or cathode or source, for triodes or FETs) connection is fed from something app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
