d) None of the mentioned The circuit diagram of an op-amp based anti-logarithmic amplifier is shown in the following figure −. 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. 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. d) 6.2v In this article, we will see the different antilog amplifier circuits, its working and antilog amplifier applications. It means zero volts is applied to its non-inverting input terminal. 1) ... What part of the characteristic curve of a diode is useful for log amplifiers? View Answer, 6. \$\endgroup\$ – … It is a non-linear amplifier used for amplification or compression of wide range of input signal for better resolution. 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. 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. They have numerous applications in electronics, such as: Basics of Integrated Circuits Applications. 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. In order to crack any major entrance test, aspirants need to practice solving logarithm questions. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. Log and AntiLog Amplifiers Recommended Text: Pallas-Areny, R. & Webster, J.G., Analog Signal Processing, Wiley (1999) pp. b) Applying input and reference voltage to same log-amps 1. Solve the equation (1/2) 2x + 1 = 1 Solve x y m = y x 3 for m.; Given: log 8 (5) = b. log a 1 = 0 and log a a = 1. shorthand/stand for the repeated multiplication of a variable To solve this problem, logarithm was invented in mathematics. The derivation of the input/output Equation is similar to the log … That means zero volts is applied at the non-inverting input terminal of the op-amp. This section discusses about the op-amp based logarithmic amplifier in detail. It can be used direct db display on spectrum analyzer. b) VO = -(kT/q)×ln(Vi/Vref) Calculate the base voltage of Q2 transistor in the log-amp using two op-amps? If in the logarithm the base is 10, then instead of log 10 we write lg. Questions on Logarithm and exponential with solutions, at the bottom of the page, are presented with detailed explanations.. Time and Work Formula and Solved Problems. Note that, in the above equation the parameters n, ${V_T}$ and $I_{s}$ are constants. 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. 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 −, $$In\left(\frac{V_i}{R_1I_s}\right)= \frac{-V_0}{nV_T}$$, $$V_{0}=-{nV_T}In\left(\frac{V_i}{R_1I_s}\right)$$. Please note that these amplifiers fall under non-linear applications. a) In(x) Note that the transistor is used to turn the input voltage into an input current, with a log function. It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. Here, y > 0, b > 0, and b ≠ 1. b) log(x) d) VO = (kT/q)×ln(Vi/Vref) 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. 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. c) Applying input and reference voltage to separate log-amps In this article, we will see the different log amplifier circuits, its working and log amplifier applications. 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. If you are looking for a reviewer in Electronics Engineering this will definitely help. This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Log and Antilog Amplifier”. 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. AntiLog amplifier or anti–logarithmic amplifier is an electronic circuit that produces output that is proportional to the anti-logarithm of the applied input. An antilog amplifier has a _____ in series with the input. 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 ${R_f}$. Find the output voltage of the log-amp? For example, if 24 = 16, then 4 is the logarithm of 16 with the base as 2. 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 … Basically it performs mathematical operation of a logarithm. $V_{f}$ is the voltage drop across diode, when it is in forward bias. The concepts of logarithm and exponential are used throughout mathematics. 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 b) VO = Vref+(10-k’vi) Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations. b) 5.3v Participate in the Sanfoundry Certification contest to get free Certificate of Merit. From log a 1 = 0 we have that a 0 = 1, which is true for any real number a. Antilog amplifier does the exact opposite of a log amplifier. a) Applying reference voltage alone to two different log-amps c) VO = -(kT/q)×ln(Vref/Vi) MCQ Exam ON : Special-Purpose Op-Amp Circuits . Anti log amplifier is one which provides output proportional to the antilog i.e. Note that in the above equation, the parameters n, ${V_T}$ and $I_{s}$ are constants. b) 0.597(kT/q)v $I_{s}$ is the saturation current of the diode. 7. The power is sometimes called the exponent. We can write it as 4 = log 2= 16. Express log 4 (10) in terms of b.; Simplify without calculator: log 6 (216) + [ log(42) - log(6) ] / log(49) You may also like: Antilogarithmic Amplifier. A. View Answer, 5. Log Amplifier using a Single Diode and Op-Amp. Output of summing amp U3 is 1.2V then. To practice all areas of Linear Integrated Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers. Applications of Anti-logarithmic Amplifier IC. a) VO = Vref/(10-k’vi) 1. Answer Questions and Earn Points !!! Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier. c) 3.3v 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. This goes into anti log amp U4. D. 4. Sanfoundry Global Education & Learning Series – Linear Integrated Circuits. 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 ${R_1I_s}=1V$. Find the circuit that is used to compress the dynamic range of a signal? The input voltage, 6v and reference voltage, 4 v are applied to a log-amp with saturation current and temperature compensation. You are allowed to answer only once per question. 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, ${R_fI_s}= 1V$. d) 1.214(kT/q)v 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 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. Join our social networks below and stay updated with latest contests, videos, internships and jobs! View Answer, 8. View Answer. 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. Multiple Choice Questions and Answers on Amplifiers with Negative Feedback. $V_{T}$ is the diode’s thermal equivalent voltage. • It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. An antilog amplifier has a _____ in series with the input. When we are solving some logarithm, any part can be unknown. 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 In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. a) 6.314(kT/q)v B. d) VO = Vref-(10-k’vi) 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. View Answer, 2. c) Sinh(x) a) 8.7v We would like to show you a description here but the site won’t allow us. So, the voltage at its inverting input terminal will be zero volts. $$=>V_{0}=-R_{f}I_{f}.........Equation 4$$, 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 −, $$V_{0}=-R_{f}{I_{s} e^{\left(\frac{V_i}{nV_T}\right)}}$$. d) All of the mentioned Log amplifier or logarithmic amplifier is an electronic circuit that produces output that is proportional to the logarithm of the applied input. View Answer, 3. Displays more accurate result than log(a,2). What are Exponents? 9. How much current would have to flow in diode-connected transistor Q4 for V+ to equal V- for U4? Basically it performs mathematical operation of an anti-logarithm. 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. exponential to the input voltage. https://www.theengineeringknowledge.com/log-and-antilog-amplifiers c) VO = Vref×(10-k’vi) 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 $R_{1}$. Time and Work Concepts. Introduction Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. You can now earn points by answering the unanswered questions listed. The circuit diagram of an op-amp based logarithmic amplifier is shown in the following figure −. From log a a = 1 we have that a 1 = a, which is true for any real number a. 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. This current then feeds \(R_f\), which produces the output voltage. https://www.sanfoundry.com/linear-integrated-circuit-mcqs-log-antilog-amplifier Which of the following functions does the antilog computation required to perform continuously with log-amps? •Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. 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 −, $$I_{f}=I_{s} e^{(\frac{V_f}{nV_T})} ......Equation 2$$. The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm (exponential) with an amplification are called as Which of the following functions does the antilog computation required to perform continuously with log-amps? Find the circuit used for compensating dependency of temperature in the output voltage? This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. 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. View Answer, 7. How to provide saturation current and temperature compensation in log-amp? Log and Antilog Amplifier. c) 0.405(kT/q)v 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. a) VO = -(kT)×ln(Vi/Vref) Determine the output voltage for the given circuit 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 other words, if by = x then y is the logarithm of x to base b. A basic anti-log amplifier is shown in Figure \(\PageIndex{3}\). View Answer, 4. All Rights Reserved. If log 3 [log 2 (x 2 – 4x – 37)] = 1, where ‘x’ is a natural number, find the value of x. C. 10. Figure 2: Anti-logarithmic Amplifier IC with antilog element in input. 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. Answer & Explanation Most Popular Articles. So, the voltage at the inverting input terminal will be zero volts. A logarithm of a number is the power to which a given base must be raised to obtain that number. Find the output voltage of the log-amplifier 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. © 2011-2021 Sanfoundry. This section discusses about the op-amp based anti-logarithmic amplifier in detail. Of Merit direct db display on spectrum analyzer log amp, but this adds the errors from the.... Amp circuits include the same elements but arranged in different Feedback configurations, the voltage at the non-inverting terminal! Than log ( a,2 ) in order to crack any major entrance test aspirants! Are applied to the logarithm ( or exponent ) of the applied input in mathematics that the transistor used... Transistor in the sanfoundry Certification contest to get free Certificate of Merit voltage! Computation required to perform continuously with log-amps shorthand/stand for the repeated multiplication of a is... R_F\ ), which is true for any real number a opposite of a variable log. What part of the applied input circuit diagram of an op-amp based logarithmic amplifier is in. But arranged in different Feedback configurations here, y > 0, b > 0, b >,! Contest to get free Certificate of Merit write it as 4 = log 2=.... Figure − the rectifier that the transistor is used to turn the input on “ log and antilog has. See the different antilog amplifier has a _____ in series with the input voltage of Q2 transistor the... Will be zero volts means zero volts is applied to its non-inverting input of! Discusses about the op-amp based logarithmic amplifier is one which provides output proportional to the antilog.! Diode ’ s thermal equivalent voltage per question a signal of Q2 transistor in the following functions does the computation! Based anti-logarithmic amplifier in detail and reference voltage, 4 v are applied to its non-inverting input terminal of applied... A signal reference voltage, 4 v are applied to the antilog.... Thermal equivalent voltage discusses about the op-amp based anti-logarithmic amplifier IC with element! Was invented in mathematics as 4 = log 2= 16 circuit, the drop... Education & Learning series – Linear Integrated circuits in Electronics Engineering this will definitely help this adds the from! Computation required to perform continuously with log-amps by = x then y is power... ) 5.3v c ) 3.3v d ) 6.2v View answer in diode-connected transistor Q4 for V+ to V-... Any major entrance test, aspirants need to practice solving logarithm questions input terminal ’ s equivalent!, are presented with detailed explanations this set of 1000+ Multiple Choice questions & (. A number is the diode log 2= 16 log and antilog amplifier mcq are applied to the logarithm 16. C ) 3.3v d ) 6.2v View answer will see the different log.. Solving some logarithm, any part can be performed by addition and of. Presented with detailed explanations into an input current, with a log amplifier shown..., b > 0, and b ≠ 1 and antilog amplifier has a _____ in with. The concepts of logarithm and exponential are used throughout mathematics antilog i.e description here but the site won ’ allow... A = 1 we have that a 0 = 1 we have that a 1 = we... Has a _____ in series with the input voltage into an input current with! That number one which provides output proportional to the antilog computation required to perform continuously with log-amps questions & (. Definitely help logarithm, any part can be unknown reference voltage, 4 v are applied its... Multiple Choice questions and Answers on Amplifiers with Negative Feedback, b 0! Displays more accurate result than log ( a,2 ) log Amplifiers s $! That a 1 = a, which is true for any real number a we can write as! The saturation current and temperature compensation major entrance test, aspirants need to solving. To compress the dynamic range of a diode is useful for log Amplifiers t } is... What part of the input this will definitely help a log-amp with saturation and. In input complete set of 1000+ Multiple Choice questions and Answers on Amplifiers with Negative log and antilog amplifier mcq current. Compress the dynamic range of a signal only once per question with log-amps to its non-inverting input terminal of characteristic... Forward bias a 0 = 1, which is true for log and antilog amplifier mcq real number a 4 v applied. Complete set of Linear Integrated circuits, its working and log amplifier questions and on. With Negative Feedback allowed to answer only once per question \ $ \endgroup\ $ – … MCQ on., 6v and reference voltage, 4 v are applied to the logarithm of a log or! Currents can be performed by addition and subtraction of logs definitely help used to turn the.. A number is the logarithm ( or exponent ) of the following figure.... 6.2V View answer ) 5.3v c ) 3.3v d ) 6.2v View answer presented detailed... In order to crack any major entrance test, aspirants need to practice all areas of Linear Integrated circuit Choice! \ ( R_f\ ), which is true for any real number a transistor! The above circuit, the non-inverting input terminal of the op-amp is connected to ground per question MCQ on! This chapter discusses about the op-amp based logarithmic amplifier is shown in the sanfoundry Certification contest to free. Elements but arranged in different Feedback configurations, y > 0, b > 0 and. The voltage at the inverting input terminal will be zero volts 1 =,. B > 0, b > 0, and b ≠ 1 for U4 the sanfoundry contest. Amp circuits include the same elements but arranged in different Feedback configurations Answers ( ). Is used to compress the dynamic range of a number is the saturation current and temperature compensation videos, and. Circuits, its working and log amplifier is shown in the output voltage shorthand/stand for the repeated multiplication a! These Amplifiers fall under non-linear applications and anti-logarithmic amplifier in detail, its working and log.! An electronic circuit that is proportional to the logarithm of a signal is useful for Amplifiers. In detail contest to get free Certificate of Merit please note that these Amplifiers under! Can be unknown presented with detailed explanations { t } $ is the at... You are looking for a reviewer in Electronics Engineering this will definitely help complete of... In log and antilog amplifier mcq Engineering this will definitely help two op-amps antilog computation required to perform continuously log-amps... Log ( a,2 ) number a diode ’ s thermal equivalent voltage ) 6.2v View.... Well known that some processes such as multiplication and division, can be used direct db display on spectrum..