That means zero volts is applied at the non-inverting input terminal of the op-amp. a) In(x) This current then feeds \(R_f\), which produces the output voltage. Note that in the above equation, the parameters n, ${V_T}$ and $I_{s}$ are constants. Applications of Anti-logarithmic Amplifier IC. In this article, we will see the different antilog amplifier circuits, its working and antilog amplifier applications. An anti-logarithmic amplifier, or an anti-log amplifier, is an electronic circuit that produces an output that is proportional to the anti-logarithm of the applied input. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. The power is sometimes called the exponent. In this article, we will see the different log amplifier circuits, its working and log amplifier applications. a) 8.7v Please note that these amplifiers fall under non-linear applications. A. log a 1 = 0 and log a a = 1. The KVL equation around the feedback loop of the op amp will be −, Substituting the value of $V_{f}$ in Equation 2, we get −, $$I_{f}=I_{s} e^{\left(\frac{-V_0}{nV_T}\right)} ......Equation 3$$, Observe that the left hand side terms of both equation 1 and equation 3 are same. An antilog amplifier has a _____ in series with the input. Here, y > 0, b > 0, and b ≠ 1. c) 0.405(kT/q)v An op-amp based logarithmic amplifier produces a voltage at the output, which is proportional to the logarithm of the voltage applied to the resistor connected to its inverting terminal. The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm (exponential) with an amplification are called as Logarithmic amplifier and Anti-Logarithmic amplifier respectively. View Answer, 5. The nodal equation at the inverting input terminal’s node is −, $$=>I_{f}=\frac{V_i}{R_1}......Equation 1$$, The following is the equation for current flowing through a diode, when it is in forward bias −, $$I_{f}=I_{s} e^{(\frac{V_f}{nV_T})} ......Equation 2$$. Antilog amplifier does the exact opposite of a log amplifier. This section discusses about the op-amp based anti-logarithmic amplifier in detail. $V_{T}$ is the diode’s thermal equivalent voltage. An antilog amplifier has a _____ in series with the input. d) 1.214(kT/q)v To practice all areas of Linear Integrated Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers. The circuit diagram of an op-amp based anti-logarithmic amplifier is shown in the following figure −. d) VO = Vref-(10-k’vi) 9. In order to crack any major entrance test, aspirants need to practice solving logarithm questions. b) 0.597(kT/q)v B. You can now earn points by answering the unanswered questions listed. A current-to-voltage converter produces a A(n) ________ amplifier provides "a barrier" between the input and output for the protection of human life or sensitive equipment. MCQ Exam ON : Special-Purpose Op-Amp Circuits . If in the logarithm the base is 10, then instead of log 10 we write lg. Observe that the output voltage $V_{0}$ has a negative sign, which indicates that there exists a 1800 phase difference between the input and the output. Calculate the base voltage of Q2 transistor in the log-amp using two op-amps? The operational amplifier circuit configurations which can perform mathematical operations such as log and antilog (exponential), including an amplification of the input signal provided to the circuit, are known as Logarithmic amplifier and Antilogarithmic amplifier respectively. Basics of Integrated Circuits Applications. b) VO = Vref+(10-k’vi) $V_{f}$ is the voltage drop across diode, when it is in forward bias. Answer Questions and Earn Points !!! This section discusses about the op-amp based logarithmic amplifier in detail. a) 6.314(kT/q)v Time and Work Formula and Solved Problems. Solve the equation (1/2) 2x + 1 = 1 Solve x y m = y x 3 for m.; Given: log 8 (5) = b. Output : Natural logarithm of 14 is : 2.6390573296152584 Logarithm base 5 of 14 is : 1.6397385131955606 2. log2(a) : This function is used to compute the logarithm base 2 of a. For example, if 24 = 16, then 4 is the logarithm of 16 with the base as 2. From log a a = 1 we have that a 1 = a, which is true for any real number a. c) VO = -(kT/q)×ln(Vref/Vi) The circuit diagram of an op-amp based logarithmic amplifier is shown in the following figure −. b) log(x) Note that the transistor is used to turn the input voltage into an input current, with a log function. 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. Hence, equate the right hand side term of those two equations as shown below −, $$\frac{V_i}{R_1}=I_{s}e^{\left(\frac{-V_0}{nV_T}\right)}$$, $$\frac{V_i}{R_1I_s}= e^{\left(\frac{-V_0}{nV_T}\right)}$$, Applying natural logarithm on both sides, we get −, $$In\left(\frac{V_i}{R_1I_s}\right)= \frac{-V_0}{nV_T}$$, $$V_{0}=-{nV_T}In\left(\frac{V_i}{R_1I_s}\right)$$. Find the circuit that is used to compress the dynamic range of a signal? You may also like: Antilogarithmic Amplifier. According to the virtual short concept, the voltage at the inverting input terminal of op-amp will be equal to the voltage present at its non-inverting input terminal. Find the output voltage of the log-amplifier 1) ... What part of the characteristic curve of a diode is useful for log amplifiers? Time and Work Concepts. $$=>V_{0}=-R_{f}I_{f}.........Equation 4$$, We know that the equation for the current flowing through a diode, when it is in forward bias, is as given below −, $$I_{f}=I_{s} e^{\left(\frac{V_f}{nV_T}\right)}$$, Substituting the value of $I_{f}$ in Equation 4, we get, $$V_{0}=-R_{f}\left \{{I_{s} e^{\left(\frac{V_f}{nV_T}\right)}}\right \}$$, $$V_{0}=-R_{f}{I_{s} e^{\left(\frac{V_f}{nV_T}\right)}}......Equation 5$$, The KVL equation at the input side of the inverting terminal of the op amp will be, Substituting, the value of in the Equation 5, we get −, $$V_{0}=-R_{f}{I_{s} e^{\left(\frac{V_i}{nV_T}\right)}}$$. The input voltage, 6v and reference voltage, 4 v are applied to a log-amp with saturation current and temperature compensation. Answer & Explanation Most Popular Articles. a) VO = -(kT)×ln(Vi/Vref) Find the circuit used for compensating dependency of temperature in the output voltage? c) Sinh(x) How much current would have to flow in diode-connected transistor Q4 for V+ to equal V- for U4? • It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. Floyd Self-test in Log and Antilog Amplifiers Floyd Self-test in Converters and Other Op-Amp Circuits If you are looking for the Multiple Choice Questions in Floyd’s Electronic Devices proceed to ➡️ Floyd: MCQ in Special-Purpose Op-Amp Circuits Anti log amplifier is one which provides output proportional to the antilog i.e. here is complete set of 1000+ Multiple Choice Questions and Answers, Prev - Linear Integrated Circuit Questions and Answers – Very High Input Impedance Circuit, Next - Linear Integrated Circuit Questions and Answers – Multiplier and Divider – 1, Linear Integrated Circuit Questions and Answers – Very High Input Impedance Circuit, Linear Integrated Circuit Questions and Answers – Multiplier and Divider – 1, Chemical Engineering Questions and Answers, Electrical Measurements Questions and Answers, Instrumentation Transducers Questions and Answers, Design of Electrical Machines Questions and Answers, Electrical Machines Questions and Answers, Wireless & Mobile Communications Questions & Answers, Electronic Devices and Circuits Questions and Answers, Basic Electrical Engineering Questions and Answers, Linear Integrated Circuits Questions and Answers, Linear Integrated Circuit Questions and Answers – Input Bias Current, Linear Integrated Circuit Questions and Answers – Basic DAC Techniques – 2, Linear Integrated Circuit Questions and Answers – Input Offset Current and Total Output Offset Voltage, Linear Integrated Circuit Questions and Answers – Instrumentation Amplifier – 2, Linear Integrated Circuit Questions and Answers – Peak Detector, Sampling & Hold Circuit and Absolute Value Output Circuit. Note that, in the above equation the parameters n, ${V_T}$ and $I_{s}$ are constants. Sanfoundry Global Education & Learning Series – Linear Integrated Circuits. In addition to reading the questions and answers on my site, I would suggest you to check the following, on amazon, as well: Question Bank in Electronics & Communication Engineering by Prem R Chadha If you are looking for a reviewer in Electronics Engineering this will definitely help. Introduction Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. b) 5.3v d) VO = (kT/q)×ln(Vi/Vref) So, the output voltage ${V_0}$ will be proportional to the anti-natural logarithm (exponential) of the input voltage ${V_i}$, for a fixed value of feedback resistance ${R_f}$. b) Applying input and reference voltage to same log-amps So, the voltage at the inverting input terminal will be zero volts. d) None of the mentioned Multiple Choice Questions and Answers on Amplifiers with Negative Feedback. Log amplifier or logarithmic amplifier is an electronic circuit that produces output that is proportional to the logarithm of the applied input. c) 3.3v D. 4. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. An op-amp based anti-logarithmic amplifier produces a voltage at the output, which is proportional to the anti-logarithm of the voltage that is applied to the diode connected to its inverting terminal. © 2011-2021 Sanfoundry. Displays more accurate result than log(a,2). Express log 4 (10) in terms of b.; Simplify without calculator: log 6 (216) + [ log(42) - log(6) ] / log(49) View Answer, 2. C. 10. https://www.sanfoundry.com/linear-integrated-circuit-mcqs-log-antilog-amplifier In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. Therefore, the op-amp based anti-logarithmic amplifier circuit discussed above will produce an output, which is proportional to the anti-natural logarithm (exponential) of the input voltage ${V_i}$ when, ${R_fI_s}= 1V$. 1. All Rights Reserved. View Answer, 3. \$\endgroup\$ – … https://www.theengineeringknowledge.com/log-and-antilog-amplifiers View Answer, 8. Multiple Choice Questions and Answers on Op-Amp ( Operational Amplifier ) In addition to reading the questions and answers on my site, I would suggest you to check the following, on amazon, as well: Question Bank in Electronics & Communication Engineering by Prem R Chadha View Answer, 7. View Answer, 4. a) VO = Vref/(10-k’vi) Questions on Logarithm and exponential with solutions, at the bottom of the page, are presented with detailed explanations.. This is the Multiple Choice Questions in Special-Purpose Op-Amp Circuits from the book Electronic Devices – Electron Flow Version and Conventional Current Version 8th Edition by Thomas L. Floyd. Basically it performs mathematical operation of an anti-logarithm. Figure 2: Anti-logarithmic Amplifier IC with antilog element in input. A basic anti-log amplifier is shown in Figure \(\PageIndex{3}\). This goes into anti log amp U4. Basically it performs mathematical operation of a logarithm. •Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm (exponential) with an amplification are called as Log and AntiLog Amplifiers Recommended Text: Pallas-Areny, R. & Webster, J.G., Analog Signal Processing, Wiley (1999) pp. Which of the following functions does the antilog computation required to perform continuously with log-amps? Banking on our enriched industry experience, we are able to offer a wide gamut of Log and Antilog Amplifier.These high performing Log and Antilog Amplifiers offered by us are non-linear 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 different industries and offer innovative range of products. The derivation of the input/output Equation is similar to the log … We can write it as 4 = log 2= 16. The compression of any wide-range input signal, analog computing circuits, linearization of exponential sources, such as transducers, certain types of audio circuits, compression and expansion circuits for voice communications. When we are solving some logarithm, any part can be unknown. To solve this problem, logarithm was invented in mathematics. We would like to show you a description here but the site won’t allow us. What are Exponents? a) Applying reference voltage alone to two different log-amps This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Log and Antilog Amplifier”. According to the virtual short concept, the voltage at the inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal. It means zero volts is applied to its non-inverting input terminal. If log 3 [log 2 (x 2 – 4x – 37)] = 1, where ‘x’ is a natural number, find the value of x. View Answer. Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations. Log Amplifier using a Single Diode and Op-Amp. So, the voltage at its inverting input terminal will be zero volts. b) VO = -(kT/q)×ln(Vi/Vref) d) All of the mentioned The log amp gives an indication of the instant-by-instant low-frequency changes in the envelope, or amplitude, of the signal in the log domain in the same way that a digital voltmeter, set to "ac volts", gives a steady (linear) reading when the input is connected to a constant amplitude sinewave and follows any adjustments to the amplitude. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. You are allowed to answer only once per question. Join our social networks below and stay updated with latest contests, videos, internships and jobs! c) VO = Vref×(10-k’vi) Determine the output voltage for the given circuit Anti-logarithmic or exponential amplifier (or simply antilog amplifier) is an op-amp circuit configuration, whose output is proportional to the exponential value or anti-log value of the input. 293-321 I ntroduction Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. It can be used direct db display on spectrum analyzer. shorthand/stand for the repeated multiplication of a variable AntiLog amplifier or anti–logarithmic amplifier is an electronic circuit that produces output that is proportional to the anti-logarithm of the applied input. Find the output voltage of the log-amp? Therefore, the op-amp based logarithmic amplifier circuit discussed above will produce an output, which is proportional to the natural logarithm of the input voltage ${V_T}$, when ${R_1I_s}=1V$. It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. How to provide saturation current and temperature compensation in log-amp? 1. The concepts of logarithm and exponential are used throughout mathematics. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier. Output of summing amp U3 is 1.2V then. Observe that the output voltage ${V_0}$ is having a negative sign, which indicates that there exists a 1800 phase difference between the input and the output. 7. c) Applying input and reference voltage to separate log-amps If V in is the input signal applied to a Anti log amplifier then the output is V o = K * exp (a * V i) where K is proportionality constant, a is constant. From log a 1 = 0 we have that a 0 = 1, which is true for any real number a. Complete Log/Antilog Amplifier External Components Not Required; Internal Reference; Temperature Compensated 6 Decades Current Operation-1 nA to 1 mA ... Offering both log and anti-log operation, model 755's price and performance are especial-ly attractive as … $I_{s}$ is the saturation current of the diode. Log and Antilog Amplifier. View Answer, 6. So, the output voltage $V_{0}$ will be proportional to the natural logarithm of the input voltage $V_{i}$ for a fixed value of resistance $R_{1}$. It is a non-linear amplifier used for amplification or compression of wide range of input signal for better resolution. They have numerous applications in electronics, such as: exponential to the input voltage. Though evolution of digital technology makes it easier to express real large numbers, but logarithm questions and solutions have not lost their relevance in the academic world. A logarithm of a number is the power to which a given base must be raised to obtain that number. d) 6.2v Which of the following functions does the antilog computation required to perform continuously with log-amps? In other words, if by = x then y is the logarithm of x to base b. We can write it as 4 = log 2= 16 = 1 perform continuously with log-amps for log Amplifiers a... Log function non-inverting input terminal social networks below and stay updated with latest contests, videos internships. Anti log amplifier throughout mathematics by answering the unanswered questions listed and Answers antilog! 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Amplifiers with Negative Feedback questions & Answers ( MCQs ) focuses on “ log and antilog amplifier has _____! The page, are presented with detailed explanations this set of Linear Integrated circuit Multiple Choice questions Answers! Elements but arranged in different Feedback configurations and anti-logarithmic amplifier IC with antilog in! 2: anti-logarithmic amplifier in detail how to provide saturation current and temperature compensation in log-amp the page are! We are solving some logarithm, any part can be unknown ( R_f\ ), which is for. That some processes such as multiplication and division, can be first rectified and then applied to non-inverting! Required to perform continuously with log-amps an op-amp based logarithmic amplifier in.! = 16, then 4 is the voltage at its inverting input terminal the. The logarithm of 16 with the input voltage, 4 v are applied to the logarithm of a diode useful. Is complete set of Linear Integrated circuits, here is complete set of 1000+ Multiple Choice questions & Answers MCQs.
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