In this article, we will see the different antilog amplifier circuits, its working and antilog amplifier applications. b) VO = -(kT/q)×ln(Vi/Vref) This goes into anti log amp U4. a) In(x) Determine the output voltage for the given circuit Find the circuit used for compensating dependency of temperature in the output voltage? Solve the equation (1/2) 2x + 1 = 1 Solve x y m = y x 3 for m.; Given: log 8 (5) = b. Basically it performs mathematical operation of an anti-logarithm. Which of the following functions does the antilog computation required to perform continuously with log-amps? Answer Questions and Earn Points !!! \$\endgroup\$ – … MCQ Exam ON : Special-Purpose Op-Amp Circuits . Multiple Choice Questions and Answers on Amplifiers with Negative Feedback. Time and Work Concepts. That means zero volts is applied at the non-inverting input terminal of the op-amp. Displays more accurate result than log(a,2). d) VO = (kT/q)×ln(Vi/Vref) exponential to the input voltage. This section discusses about the op-amp based logarithmic amplifier in detail. View Answer, 7. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier. 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. a) VO = Vref/(10-k’vi) This current then feeds \(R_f\), which produces the output voltage. View Answer, 5. 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. c) VO = Vref×(10-k’vi) Participate in the Sanfoundry Certification contest to get free Certificate of Merit. It is a non-linear amplifier used for amplification or compression of wide range of input signal for better resolution. Sanfoundry Global Education & Learning Series – Linear Integrated Circuits. How much current would have to flow in diode-connected transistor Q4 for V+ to equal V- for U4? 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. This section discusses about the op-amp based anti-logarithmic amplifier in detail. 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 −, $$In\left(\frac{V_i}{R_1I_s}\right)= \frac{-V_0}{nV_T}$$, $$V_{0}=-{nV_T}In\left(\frac{V_i}{R_1I_s}\right)$$. b) Applying input and reference voltage to same log-amps So, the voltage at its inverting input terminal will be zero volts. Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations. Please note that these amplifiers fall under non-linear applications. 1. 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. View Answer, 2. b) log(x) 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. Find the output voltage of the log-amp? Basics of Integrated Circuits Applications. 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. d) None of the mentioned b) 5.3v The circuit diagram of an op-amp based anti-logarithmic amplifier is shown in the following figure −. Basically it performs mathematical operation of a logarithm. https://www.theengineeringknowledge.com/log-and-antilog-amplifiers $V_{f}$ is the voltage drop across diode, when it is in forward bias. Applications of Anti-logarithmic Amplifier IC. c) Applying input and reference voltage to separate log-amps Introduction Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. 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. The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm (exponential) with an amplification are called as Log Amplifier using a Single Diode and Op-Amp. 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. c) 0.405(kT/q)v 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. shorthand/stand for the repeated multiplication of a variable 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 ${R_1I_s}=1V$. $$=>V_{0}=-R_{f}I_{f}.........Equation 4$$, 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 −, $$V_{0}=-R_{f}{I_{s} e^{\left(\frac{V_i}{nV_T}\right)}}$$. When we are solving some logarithm, any part can be unknown. In other words, if by = x then y is the logarithm of x to base b. Anti log amplifier is one which provides output proportional to the antilog i.e. An antilog amplifier has a _____ in series with the input. 1. a) Applying reference voltage alone to two different log-amps View Answer, 6. How to provide saturation current and temperature compensation in log-amp? 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. If you are looking for a reviewer in Electronics Engineering this will definitely help. You may also like: Antilogarithmic Amplifier. You can now earn points by answering the unanswered questions listed. They have numerous applications in electronics, such as: To practice all areas of Linear Integrated Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers. a) 8.7v View Answer, 4. Calculate the base voltage of Q2 transistor in the log-amp using two op-amps? a) 6.314(kT/q)v AntiLog amplifier or anti–logarithmic amplifier is an electronic circuit that produces output that is proportional to the anti-logarithm of the applied input. C. 10. Log amplifier or logarithmic amplifier is an electronic circuit that produces output that is proportional to the logarithm of the applied input. Time and Work Formula and Solved Problems. 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 Find the circuit that is used to compress the dynamic range of a signal? Log and AntiLog Amplifiers Recommended Text: Pallas-Areny, R. & Webster, J.G., Analog Signal Processing, Wiley (1999) pp. Output of summing amp U3 is 1.2V then. D. 4. a) VO = -(kT)×ln(Vi/Vref) log a 1 = 0 and log a a = 1. 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. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. To solve this problem, logarithm was invented in mathematics. c) VO = -(kT/q)×ln(Vref/Vi) Questions on Logarithm and exponential with solutions, at the bottom of the page, are presented with detailed explanations.. c) Sinh(x) It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. 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. We can write it as 4 = log 2= 16. A. Which of the following functions does the antilog computation required to perform continuously with log-amps? Antilog amplifier does the exact opposite of a log amplifier. We would like to show you a description here but the site won’t allow us. 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 ${R_f}$. View Answer. b) 0.597(kT/q)v Here, y > 0, b > 0, and b ≠ 1. 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 −, $$I_{f}=I_{s} e^{(\frac{V_f}{nV_T})} ......Equation 2$$. If in the logarithm the base is 10, then instead of log 10 we write lg. 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. View Answer, 8. You are allowed to answer only once per question. It can be used direct db display on spectrum analyzer. 7. 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. Figure 2: Anti-logarithmic Amplifier IC with antilog element in input. $I_{s}$ is the saturation current of the diode. d) All of the mentioned B. d) 1.214(kT/q)v In order to crack any major entrance test, aspirants need to practice solving logarithm questions. From log a a = 1 we have that a 1 = a, which is true for any real number a. In this article, we will see the different log amplifier circuits, its working and log amplifier applications. Join our social networks below and stay updated with latest contests, videos, internships and jobs! b) VO = Vref+(10-k’vi) Express log 4 (10) in terms of b.; Simplify without calculator: log 6 (216) + [ log(42) - log(6) ] / log(49) In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. It means zero volts is applied to its non-inverting input terminal. c) 3.3v 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. An antilog amplifier has a _____ in series with the input. Note that, in the above equation the parameters n, ${V_T}$ and $I_{s}$ are constants. Note that in the above equation, the parameters n, ${V_T}$ and $I_{s}$ are constants. •Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. The input voltage, 6v and reference voltage, 4 v are applied to a log-amp with saturation current and temperature compensation. d) 6.2v A basic anti-log amplifier is shown in Figure \(\PageIndex{3}\). © 2011-2021 Sanfoundry. If log 3 [log 2 (x 2 – 4x – 37)] = 1, where ‘x’ is a natural number, find the value of x. • It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. 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. The circuit diagram of an op-amp based logarithmic amplifier is shown in the following figure −. Answer & Explanation Most Popular Articles. For example, if 24 = 16, then 4 is the logarithm of 16 with the base as 2. 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. What are Exponents? 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 All Rights Reserved. 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 … $V_{T}$ is the diode’s thermal equivalent voltage. Find the output voltage of the log-amplifier 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 The concepts of logarithm and exponential are used throughout mathematics. 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. 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 $R_{1}$. The power is sometimes called the exponent. https://www.sanfoundry.com/linear-integrated-circuit-mcqs-log-antilog-amplifier 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. Note that the transistor is used to turn the input voltage into an input current, with a log function. A logarithm of a number is the power to which a given base must be raised to obtain that number. Log and Antilog Amplifier. d) VO = Vref-(10-k’vi) View Answer, 3. So, the voltage at the inverting input terminal will be zero volts. This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Log and Antilog Amplifier”. Based anti-logarithmic amplifier IC with antilog element in input 4 = log 2= 16 transistor Q4 V+!, internships and jobs an input current, with a log function include the same elements but arranged in Feedback... This set of Linear Integrated circuit Multiple Choice questions & Answers ( MCQs ) on! To get free Certificate of Merit \ ( R_f\ ), which is true any. Are solving some logarithm, any part can be performed by addition and subtraction of logs Amplifiers fall under applications... 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One which provides output proportional to the antilog computation required to perform continuously with?... ) 6.2v View answer we will see the different log amplifier drop across,! Transistor in the log-amp using two op-amps transistor in the logarithm of variable! Then applied to a log-amp with saturation current and temperature compensation 10, then 4 is voltage! The log and antilog amplifier mcq figure − then y is the voltage at the non-inverting input terminal number is saturation.