a) 6.314(kT/q)v In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. When we are solving some logarithm, any part can be unknown. 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. If in the logarithm the base is 10, then instead of log 10 we write lg. 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. Which of the following functions does the antilog computation required to perform continuously with log-amps? 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. c) Sinh(x) b) 0.597(kT/q)v Solve the equation (1/2) 2x + 1 = 1 Solve x y m = y x 3 for m.; Given: log 8 (5) = b. d) VO = Vref-(10-k’vi) B. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier. We can write it as 4 = log 2= 16. Find the output voltage of the log-amp? d) 6.2v In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. Log and Antilog Amplifier. 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. 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 $R_{1}$. View Answer, 8. b) VO = Vref+(10-k’vi) Find the circuit used for compensating dependency of temperature in the output voltage? View Answer. AntiLog amplifier or anti–logarithmic amplifier is an electronic circuit that produces output that is proportional to the anti-logarithm of the applied input. It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. In other words, if by = x then y is the logarithm of x to base b. Questions on Logarithm and exponential with solutions, at the bottom of the page, are presented with detailed explanations.. Time and Work Concepts. 7. Find the circuit that is used to compress the dynamic range of a signal? If log 3 [log 2 (x 2 – 4x – 37)] = 1, where ‘x’ is a natural number, find the value of x. Basically it performs mathematical operation of a logarithm. Multiple Choice Questions and Answers on Amplifiers with Negative Feedback. b) Applying input and reference voltage to same log-amps Basically it performs mathematical operation of an anti-logarithm. Answer & Explanation Most Popular Articles. D. 4. 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 −, $$In\left(\frac{V_i}{R_1I_s}\right)= \frac{-V_0}{nV_T}$$, $$V_{0}=-{nV_T}In\left(\frac{V_i}{R_1I_s}\right)$$. It is a non-linear amplifier used for amplification or compression of wide range of input signal for better resolution. In this article, we will see the different antilog amplifier circuits, its working and antilog amplifier applications. • It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. Log Amplifier using a Single Diode and Op-Amp. Log amplifier or logarithmic amplifier is an electronic circuit that produces output that is proportional to the logarithm of the applied input. 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 … 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. So, the voltage at its inverting input terminal will be zero volts. Sanfoundry Global Education & Learning Series – Linear Integrated Circuits. View Answer, 2. This section discusses about the op-amp based logarithmic amplifier in detail. 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. We would like to show you a description here but the site won’t allow us. 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, ${R_fI_s}= 1V$. 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) In(x) c) VO = -(kT/q)×ln(Vref/Vi) Calculate the base voltage of Q2 transistor in the log-amp using two op-amps? \$\endgroup\$ – … Antilog amplifier does the exact opposite of a log amplifier. What are Exponents? Log and AntiLog Amplifiers Recommended Text: Pallas-Areny, R. & Webster, J.G., Analog Signal Processing, Wiley (1999) pp. Basics of Integrated Circuits Applications. c) 0.405(kT/q)v You can now earn points by answering the unanswered questions listed. d) VO = (kT/q)×ln(Vi/Vref) Figure 2: Anti-logarithmic Amplifier IC with antilog element in input. https://www.theengineeringknowledge.com/log-and-antilog-amplifiers b) 5.3v A basic anti-log amplifier is shown in Figure \(\PageIndex{3}\). 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 ${R_1I_s}=1V$. 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. The circuit diagram of an op-amp based anti-logarithmic amplifier is shown in the following figure −. b) VO = -(kT/q)×ln(Vi/Vref) 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. For example, if 24 = 16, then 4 is the logarithm of 16 with the base as 2. Time and Work Formula and Solved Problems. c) Applying input and reference voltage to separate log-amps 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. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. 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. log a 1 = 0 and log a a = 1. 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 voltage at the inverting input terminal will be zero volts. View Answer, 5. Introduction 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. a) 8.7v C. 10. From log a a = 1 we have that a 1 = a, which is true for any real number a. The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm (exponential) with an amplification are called as 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. 1. In this article, we will see the different log amplifier circuits, its working and log amplifier applications. 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. Note that, in the above equation the parameters n, ${V_T}$ and $I_{s}$ are constants. 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. View Answer, 3. exponential to the input voltage. 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 It means zero volts is applied to its non-inverting input terminal. To solve this problem, logarithm was invented in mathematics. d) None of the mentioned The input voltage, 6v and reference voltage, 4 v are applied to a log-amp with saturation current and temperature compensation. They have numerous applications in electronics, such as: d) All of the mentioned Answer Questions and Earn Points !!! d) 1.214(kT/q)v How much current would have to flow in diode-connected transistor Q4 for V+ to equal V- for U4? The power is sometimes called the exponent. 1) ... What part of the characteristic curve of a diode is useful for log amplifiers? $$=>V_{0}=-R_{f}I_{f}.........Equation 4$$, 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 −, $$V_{0}=-R_{f}{I_{s} e^{\left(\frac{V_i}{nV_T}\right)}}$$. An antilog amplifier has a _____ in series with the input. 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. 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 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. 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