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Fully Differential Amplifier
A fully differential amplifier (FDA) is a DC-coupled high-gain electronic voltage amplifier with differential inputs and differential outputs. In its ordinary usage, the output of the FDA is controlled by two feedback paths which, because of the amplifier's high gain, almost completely determine the output voltage for any given input. In a fully differential amplifier, common-mode noise such as power supply disturbances is rejected; this makes FDAs especially useful as part of a mixed-signal integrated circuit. An FDA is often used to convert an analog signal into a form more suitable for driving into an analog-to-digital converter; many modern high-precision ADCs have differential inputs.Rick"ADC Input Driver FULLY DIFFERENTIAL AMPLIFIER" The ideal FDA For any input voltages, the ideal FDA has infinite open-loop gain, infinite bandwidth, infinite input impedances resulting in zero input currents, infinite slew rate, zero output impedance and zero noise. In the ideal FDA, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Current
Direct current (DC) is one-directional electric current, flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor (material), conductor such as a wire, but can also flow through semiconductors, electrical insulation, insulators, or even through a vacuum as in electron beam, electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A archaism, term formerly used for this type of current was galvanic current. The abbreviations ''AC'' and ''DC'' are often used to mean simply ''alternating'' and ''direct'', as when they modify ''Electric current, current'' or ''voltage''. Direct current may be converted from an alternating current supply by use of a rectifier, which contains Electronics, electronic elements (usually) or electromechanical elements (historically) that allow current to flow only in one direction. Direct current may be converted into alt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Circuit
An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components are etched onto a small, flat piece ("chip") of semiconductor material, usually silicon. Integrated circuits are used in a wide range of electronic devices, including computers, smartphones, and televisions, to perform various functions such as processing and storing information. They have greatly impacted the field of electronics by enabling device miniaturization and enhanced functionality. Integrated circuits are orders of magnitude smaller, faster, and less expensive than those constructed of discrete components, allowing a large transistor count. The IC's mass production capability, reliability, and building-block approach to integrated circuit design have ensured the rapid adoption of standardized ICs in place of designs using discre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pole Splitting
Pole splitting is a phenomenon exploited in some forms of frequency compensation used in an electronic amplifier. When a capacitor is introduced between the input and output sides of the amplifier with the intention of moving the pole lowest in frequency (usually an input pole) to lower frequencies, pole splitting causes the pole next in frequency (usually an output pole) to move to a higher frequency. This pole movement increases the stability of the amplifier and improves its step response at the cost of decreased speed. Example of pole splitting This example shows that introducing capacitor CC in the amplifier of Figure 1 has two results: firstly, it causes the lowest frequency pole of the amplifier to move still lower in frequency and secondly, it causes the higher pole to move higher in frequency. This amplifier has a low frequency pole due to the added input resistance ''Ri'' and capacitance ''Ci'', with the time constant ''Ci'' ( ''RA , , Ri'' ). This pole is low ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Supply
A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, electric current, current, and frequency to power the load. As a result, power supplies are sometimes referred to as electric power converters. Some power supplies are separate standalone pieces of equipment, while others are built into the load appliances that they power. Examples of the latter include power supplies found in desktop computers and consumer electronics devices. Other functions that power supplies may perform include limiting the current drawn by the load to safe levels, shutting off the current in the event of an electrical fault, power conditioning to prevent electronic noise or voltage surges on the input from reaching the load, power-factor correction, and storing energy so it can continue to power the load in the event of a temporary interruption in the source power ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clipping (signal Processing)
Clipping is a form of distortion that limits a signal once it exceeds a threshold. Clipping may occur when a signal is recorded by a sensor that has constraints on the range of data it can measure, it can occur when a signal is digitized, or it can occur any other time an analog or digital signal is transformed, particularly in the presence of gain or overshoot and undershoot. Clipping may be described as hard, in cases where the signal is strictly limited at the threshold, producing a flat cutoff; or it may be described as soft, in cases where the clipped signal continues to follow the original at a reduced gain. Hard clipping results in many high-frequency harmonics; soft clipping results in fewer higher-order harmonics and intermodulation distortion components. Audio In the frequency domain, clipping produces strong harmonics in the high-frequency range (as the clipped waveform comes closer to a square wave). The extra high-frequency weighting of the signal could ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capacitance
Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related notions of capacitance: ''self capacitance'' and ''mutual capacitance''. An object that can be electrically charged exhibits self capacitance, for which the electric potential is measured between the object and ground. Mutual capacitance is measured between two components, and is particularly important in the operation of the capacitor, an elementary linear electronic component designed to add capacitance to an electric circuit. The capacitance between two conductors depends only on the geometry; the opposing surface area of the conductors and the distance between them; and the permittivity of any dielectric material between them. For many dielectric materials, the permittivity, and thus the capacitance, is independent of the potential ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Margin
In electronic amplifiers, the phase margin (PM) is the difference between the phase (waves), phase lag (< 0) and -180°, for an amplifier's output signal (relative to its input) at zero dB gain - i.e. unity gain, or that the output signal has the same amplitude as the input. :. For example, if the amplifier's open-loop gain crosses 0 dB at a frequency where the phase lag is -135°, then the phase margin of this feedback system is -135° -(-180°) = 45°. Theory Typically the Feedback#Electronic_engineering, open-loop phase lag (relative to input, < 0) varies with frequency, progressively increasing to exceed 180°, at which frequency the output signal becomes inverted, or antiphase in relation to the input. The PM will be positive but decreasing at frequencies less than the frequency at which inversion sets in (at which PM = 0), and PM is negative (PM < 0) at higher frequencies. In the presence of negative feedba ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Compensation
In electronics engineering, frequency compensation is a technique used in amplifiers, and especially in amplifiers employing negative feedback. It usually has two primary goals: To avoid the unintentional creation of positive feedback, which will cause the amplifier to oscillate, and to control overshoot and ringing in the amplifier's step response. It is also used extensively to improve the bandwidth of single pole systems. Explanation Most amplifiers use negative feedback to trade gain for other desirable properties, such as decreased distortion, improved noise reduction or increased invariance to variation of parameters such as temperature. Ideally, the phase characteristic of an amplifier's frequency response would be linear; however, device limitations make this goal physically unattainable. More particularly, capacitances within the amplifier's gain stages cause the output signal to lag behind the input signal by up to 90° for each pole they create. If the sum of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common-mode Rejection Ratio
In electronics, the common mode rejection ratio (CMRR) of a differential amplifier (or other device) is a metric used to quantify the ability of the device to reject common-mode signals, i.e. those that appear simultaneously and in-phase on both inputs. An ideal differential amplifier would have infinite CMRR, however this is not achievable in practice. A high CMRR is required when a differential signal must be amplified in the presence of a possibly large common-mode input, such as strong electromagnetic interference (EMI). An example is audio transmission over balanced line in sound reinforcement or recording. CMRR of an amplifier Ideally, a differential amplifier takes the voltages, V_+ and V_- on its two inputs and produces an output voltage V_\mathrm=A_\mathrm(V_+ - V_-), where A_\mathrm is the differential gain. However, the output of a real differential amplifier is better described as : :V_ = A_\mathrm (V_+ - V_-) + \tfrac A_\mathrm (V_+ + V_-) where A_\mathrm is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage
Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), work needed per unit of Electric charge, charge to move a positive Test particle#Electrostatics, test charge from the first point to the second point. In the SI unit, International System of Units (SI), the SI derived unit, derived unit for voltage is the ''volt'' (''V''). The voltage between points can be caused by the build-up of electric charge (e.g., a capacitor), and from an electromotive force (e.g., electromagnetic induction in a Electric generator, generator). On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect, and the thermoelectric effect. Since it is the difference in electric potential, it is a physical Scalar (physics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss ", , ) is a type of MOSFET, metal–oxide–semiconductor field-effect transistor (MOSFET) semiconductor device fabrication, fabrication process that uses complementary and symmetrical pairs of p-type semiconductor, p-type and n-type semiconductor, n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips (including Nonvolatile BIOS memory, CMOS BIOS), and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors (CMOS sensors), data conversion, data converters, RF circuits (RF CMOS), and highly integrated transceivers for many types of communication. In 1948, Bardeen and Brattain patented an insulated-gate transistor (IGFET) with an inversion layer. Bardeen's concept forms the basis of CMOS technology today. The CMOS process was presented by Fairchild Semico ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Junction Transistor
A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor (FET), uses only one kind of charge carrier. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current between the remaining two terminals, making the device capable of amplification or switching. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. Diffused trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
