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