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This article is about electronic analog multipliers. Two digital voltmeters The field of electronics is the study and use of electronic devices that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. ...
An analog multiplier is a device which takes two analog signals and produces an output which is their product. In many (if not most) applications they are used in what most non mathematicians would consider to be a divider, that is they multiply by a fraction in order to obtain a division. Of course it is also possible to use such circuits to implement related functions such as squares (apply signal to both inputs), and square roots. An analog or analogue signal is any continuously variable signal. ...
An electronic analog multipler can be called by several names, depending on the function it is used to serve (see analog multiplier applications).
Voltage controlled amplifer Vs Analog Multiplier
If one input of an analog multiplier is held at a steady state voltage, a signal at the second input will be scaled in proportion to the level on the fixed input. In this case the analog multiplier may be considered to be a voltage controlled amplifier. Obvious applications would be for electronic volume control and automatic gain controls. It should be noted that allthougth analog multipliers are often used for such applications, voltage controlled amplifiers are not necessarily true analog multipliers. For example, an Integrated circuit designed to be used as a volume control may have a signal input designed for 1Vp-p, and a control input designed for 0-5V dc, that is the two inputs are not symetrical and the control input will have a limited bandwidth. A voltage-controlled amplifier is an electronic amplifier that varies its gain depending on a control voltage (often abbreviated CV). ...
Optical Microscope image of an integrated circuit showing defects in the aluminium layer deposition. ...
By contrast, in what is generally considered to be a true analog multiplier the two signal inputs have identical characteristics. Applications specific to a true analog multiplier are those where both inputs will be signals, for example in a Frequency mixer or an analog circuit to implement a Discrete Fourier transform. In telecommunication, a mixer is a nonlinear circuit or device that accepts as its input two different frequencies and presents at its output (a) a signal equal in frequency to the sum of the frequencies of the input signals, (b) a signal equal in frequency to the difference between the...
In mathematics, the discrete Fourier transform (DFT), sometimes called the finite Fourier transform, is a Fourier transform widely employed in signal processing and related fields to analyze the frequencies contained in a sampled signal, solve partial differential equations, and to perform other operations such as convolutions. ...
A 4 quadrant multiplier is one where inputs and outputs may swing positive and negative. Many multipliers only work in 2 quadrants (one input may only have one polarity), or single quadrant (inputs and outputs have only one polarity, usually all positive).
Analog Multiplier devices Most analog multiplier circuits are incorporated into integrated circuits designed for specific application functions, such as a True RMS converter, however a number of general purpose analog multiplier building blocks are available such as the AD834 device from Analog Devices. General purpose devices will usually include attenuators and/or amplifiers on the inputs or outputs in order to allow the signal to be scaled within the voltage limits of the circuit. When measuring the value of an alternating current signal it is often necessary to convert the signal into a direct current signal of equivalent value (known as the RMS, Root Mean square, value). ...
Allthougth analog multiplier circuits are very similar to operational amplifiers, they are far more suseptible to noise and offset voltage related problems as these errors may become multiplied. When dealing with high frequency signals, phase related problems may be quite complex. For this reason manufacturing wide range general purpose analog multipliers is far more difficult than ordinary operational amplifiers, and such devices will typically be produced using specialist technologies and laser trimming such as those used for high performance amplifiers such as Instrumentation amplifiers. This means they have a relatively high cost and so they are generally used only for circuits where they are indespensible. An operational amplifier or op-amp is an electronic circuit module (normally built as an integrated circuit, but occasionally with discrete transistors or vacuum tubes) which has a non-inverting input (+), an inverting input (-) and one output. ...
Decline of the analog multiplier In most cases the functions performed by an analog multiplier may be performed better and at lowwer cost using Digital Signal Processing techniques. At low frequencies a digital solution will be cheaper and more effective, and allows the circuit function to be modified in firmware. As frequencies rise the cost of implementing digital soltions increases much more steeply than analog solutions. As digital technology advances, the use of analog multipliers tends to be ever more marginalised towards higher frequency circuits or very specialist applications. Digital signal processing (DSP) is the study of signals in a digital representation and the processing methods of these signals. ...
In addition, most signals are now destined to become digitialised sooner or later in the signal path, and if at all possible the functions which would require a multiplier tend to be moved to the digital side. For example, in early Digital multimeters, true RMS functions were proveded by external analog multiplier circuits. Nowdays (with the exception of high frequency measurements) the tendency is to increase the sampling rate of the DAC in order to Digitialise the input signal allowing RMS and a whole range of other functions to be carried out by a digital processor. In electronics, a digital-to-analog converter (DAC or D-to-A) is a device for converting a digital (usually binary) code to an analogue signal (current, voltage or charges). ...
In addition, digitally controlled resistors allow microcontrollers to implement many functions such as tone control and AGC without having to process the digitialised signal directly. A microcontroller is a computer-on-a-chip optimised to control devices. ...
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