Log and anti log amplifiers the electronic circuits which perform the. In this paper, a new currentmode logantilog amplifier based on cdta is proposed. An anti logarithmic amplifier, or an antilog amplifier, is an electronic circuit that produces an output that is proportional to the anti logarithm of the applied input. Note that the transistor is used to turn the input voltage into an input current, with a log function.
An antilogarithmic amplifier, or an anti log amplifier, is an electronic circuit that produces an output that is proportional to the antilogarithm of the applied input. A log number can then be returned to its original number. Stresses above those listed in absolute maximum ratings may cause permanent damage to the device. Spice simulation of voltage multiplier using log and antilog amplifier.
Log and antilog amplifier manufacturer from chennai. There are three basic architectures which may be used to produce log amps. Mar 15, 2020 antilog is inverse operation of log operation so. Put another way, it undoes what calculating the logarithm of a number does and simply returns that number. Basic antilog amplifier using diode the circuit diagram of basic antilog.
A new logantilog current amplifier has been presented. Spice simulation of voltage multiplier using log and antilog. Log antilog amplifiers pdf new pdf download service. Finally, its the antilog, or exponential amplifier. Pdf lm108 log and antilog amplifier national linear brief 4 vishay ultronix grand junction co q81 sensistor widlar c1995 lm102 an30 570x. Rs 4,250 unit get latest price banking on our enriched industry experience, we are able to offer a wide gamut of log and antilog amplifier. I have not read the book myself however been introduced a few of the concept throug eric ries. The differential input amplifier allows dualpolarity inputs, is selfcompensating for temperature variations, and is relatively insensitive to commonmode noise.
The basic output equation of a log amplifier is v vout k ln vinvref. Analog and antilog article about innovation learnbus. The term logarithmic amplifier generally abbreviated to log amp is. There are many important nonlinear amplifier circuits, including the log amplifier and the antilog amplifier. So a transistor can also be used in the feedback loop of an opamp.
An opamp based antilogarithmic amplifier produces a voltage at the output, which is. Increase the input voltage in the step of 1v up to 20v. To compute the antilog of a number y, you must raise the logarithm base b usually 10, sometimes the constant e to the. Logarithmic and antilogarithmic amplifiers electronics. In this video, the log and antilog amplifier circuits using opamp and their. But the log of 0, to any base, approaches negative infinity. Nevertheless, it is quite important not to forget the sign of the signal. This section discusses about the opamp based antilogarithmic amplifier in detail. Jan 27, 2018 antilog amplifier using op amp and transistor application of antilog amplifier. Logarithms had originally developed to simplify complex arithmetic calculations. It is well known that some processes such as multiplication and. May 29, 2018 in this video, the log and antilog amplifier circuits using opamp and their applications have been discussed. Jul 03, 2019 antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals.
But if diode current is too low then the op amp input offsets become then finally choose a max temp difference of the log and antilog diodes. The circuit employs one cdta and two diodes for log amplifier and one switched capacitor, one diode and one cdta for antilog amplifier. Aug 25, 2019 antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. If x is the logarithm of a number y with a given base b, then y is the antilogarithm of antilog of x to the base b. The circuit of an antilog amplifier using op amp is shown in the figure below. Anti log amplifier is one which provides output proportional to the anti log i. Antilog can be found out from antilog table in the same manner as log, the main difference is that an antilog table contains numbers from.
A007 using the icl80468049 monolithic logantilog amplifier, by ray hendry. The voltage across a silicon diode is proportional to the logarithm of the current through it. A log amplifier is commonly used to compress a signals largeamplitude dynamic range into something more manageable by other circuits such as adcs. Hence applying kcl wmplifier inverting terminal of opamp, we get. Examples of integratedcircuit log and antilog amplifiers are the lcl 8048 log and lel. In this video, the log and antilog amplifier circuits using opamp and their applications have been discussed.
They designed to transform multiplicative processes into additive ones. This section discusses about the op amp based anti logarithmic amplifier in detail. Introduction log and antilog amplifiers are nonlinear circuits in which the output voltage is proportional to the logarithm or exponent of the input. We take into account the ever changing requirements of. There are several applications of log and antilog amplifiers. Aug 10, 2019 antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. If r3 is driven by an input voltage, rather than the 15 v reference, the output of the log generator is the log ratio of the input current to the current through r3. The following topics have been covered in this video. Log and antilog amplifiers explained applications of log and. Similarly for antilog amplifier v 0 r f i s circuit diagram. Pdf the paper presents log and antilog amplifier using current differencing transconductance amplifier cdta. Technologry ssm 21oo monolithic logantilog amplifier.
Icl8049 datasheet23 pages intersil antilog amplifier. Jan 22, 2019 antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. That means the log operation or antilog operation is single quadrant operation. A007 using the icl80468049 monolithic log antilog amplifier, by ray hendry. Logarithm of a number is defined as the exponent to which another fixed value, the base, must be raised to produce that number. Log and antilog are important circuits in what is called analog multiplicationcomputation. An antilogarithmic amplifier, or an antilog amplifier, is an electronic circuit that produces an output that is proportional to the antilogarithm of the applied input. Natural logarithms and antilogarithms have their base as 2. An op amp based anti logarithmic amplifier produces a voltage at the output, which is. The circuit of an antilog amplifier using opamp is shown in the figure below. Jan 04, 2020 antilog is inverse operation of log operation so.
They have numerous applications in electronics, such as. Unlike the normal digital computers you see these days, the analog. When working with a log amplifier that uses a diode as the log element, things get more complicated even than the math. It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. Antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. The circuit here a general purpose npn transistor is connected to inverting input of opamp. Analog 6decade, high accuracy devices log, antilog amplifiers. It is important to note that a single polarity of current can only forward bias the diode.
Spice simulation of voltage multiplier using log and. This type of log amp can be considered to be a video amp with a logarithmic characteristic, and may be known as a logarithmic video log video amplifier or, sometimes, a true log amp. Note that if you put in 0v, then you would have zero current through the diode and,ideally, 0v at the output. In an equation of the form log b x y, it is the x term, called the argument of the log function.
He is a well renowed speaker and former ceo of lukas arts entertainment he wrote the book getting to plan b a book about managing innovation. This circuit enjoys excellent temperature stability and is very suitable for implementation in cmos technology. Principle of operation log operation is obtained by placing the antilog element in the feedback loop of the op amp as shown in figure 1. These high performing log and antilog amplifiers offered by us are nonlinear circuits, in which the output voltage is proportional to the logarithm or exponent of the input. A log amplifier is an amplifier for which the output voltage v out is k times the natural log of the input voltage v in. A logarithmic amplifier, or a log amplifier, is an electronic circuit that produces an output.
The first stage takes the natural log of two inputs, which is summed by the inverting adder in the second stage, inverted using a unity gain inverting stage, and finally sent to an antilog stage to get the product of two signals. Likewise, antilog functions to exponentiate a simplified log value. Jul 21, 2015 logarithms had originally developed to simplify complex arithmetic calculations. Note the output voltage for all the input voltages. Apr 10, 2019 antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. Log and antilog amplifiers are nonlinear circuits in which the output voltage is proportional to the logarithm or exponent of the input. May 18, 2019 log antilog amplifiers pdf posted on may 18, 2019 by admin introduction log and antilog amplifiers are nonlinear circuits in which the output voltage is proportional to the logarithm or exponent of the input. When used as a log generator, the current through r3 was held constant by connecting r3 to a fixed voltage.
An antilog is the result of raising the base being used to the logarithm given or calculated. It is noted that by exchanging the positions of the transistor and the resistor, the log amplifier can be made to work as antilog amplifier. Log and antilog amplifiers explained applications of log. The antilogarithm of a number is the inverse process of finding the logarithms of the same number. The derivation of the inputoutput equation is similar to the log circuits. One operation can be that, these log and antilog amps can be used for making multipliers. Log amplifier is a linear circuit in which the output voltage will be a constant times the natural logarithm of the input. Logarithmic amplifier an overview sciencedirect topics. If vi is the input signal applied to a anti log amplifier then the output is vokexpavi where k.
Each pair is a 15db log subsection, and each input feeds two pairs, for a range of 30db. The circuit diagram of logarithmic amplifier is as shown below. Jan 18, 2020 log antilog amplifiers pdf posted on january 18, 2020 introduction log and antilog amplifiers are nonlinear circuits in which the output voltage is proportional to the logarithm or exponent of the input. Analog 6decade, high accuracy devices log, antilog. Alternatively, the log amp can be preceded by a precision current inverter. If v i is the input signal applied to a anti log amplifier then the output is v o kexpav i where k is proportionality constant, a is constant.
The logarithms and antilogarithms with base 10 can be. The proposed circuit employs single cdta, diodes and a switched c apacitor, which is very much suitable for implementation in cmos. A logarithmic amplifier or a log amplifier is an electronic circuit that produces an output that is proportional to the logarithm of the applied input. In the logarithmic mode, the overall circuit provides the transfer f unction. Pdf log and antilog amplifiers chandreyee mukherjee. The circuit below is the antilog circuit, and it too is inverting so log and antilog can be cascaded directly. Use log and antilog calculator to determine the logarithmic and antilogarithmic values with base values of 2 or e or 10. Apr 18, 2019 antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals.
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