To solve this problem, logarithm was invented in mathematics. So, the voltage at its inverting input terminal will be zero volts. An antilog amplifier has a _____ in series with the input. 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. d) VO = (kT/q)×ln(Vi/Vref) Join our social networks below and stay updated with latest contests, videos, internships and jobs! A basic anti-log amplifier is shown in Figure \(\PageIndex{3}\). $V_{T}$ is the diode’s thermal equivalent voltage. View Answer, 6. C. 10. How much current would have to flow in diode-connected transistor Q4 for V+ to equal V- for U4? How to provide saturation current and temperature compensation in log-amp? 1) ... What part of the characteristic curve of a diode is useful for log amplifiers? From log a a = 1 we have that a 1 = a, which is true for any real number a. d) All of the mentioned In this article, we will see the different log amplifier circuits, its working and log amplifier applications. Calculate the base voltage of Q2 transistor in the log-amp using two op-amps? Antilog amplifier does the exact opposite of a log amplifier. Which of the following functions does the antilog computation required to perform continuously with log-amps? 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, 3. Determine the output voltage for the given circuit b) Applying input and reference voltage to same log-amps View Answer, 7. We would like to show you a description here but the site won’t allow us. $V_{f}$ is the voltage drop across diode, when it is in forward bias. 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. Note that the transistor is used to turn the input voltage into an input current, with a log function. a) VO = -(kT)×ln(Vi/Vref) 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 … The power is sometimes called the exponent. Time and Work Formula and Solved Problems. They have numerous applications in electronics, such as: Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations. d) VO = Vref-(10-k’vi) D. 4. 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. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier. a) Applying reference voltage alone to two different log-amps 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 c) 0.405(kT/q)v 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. Find the circuit that is used to compress the dynamic range of a signal? B. Answer Questions and Earn Points !!! 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. https://www.theengineeringknowledge.com/log-and-antilog-amplifiers The input voltage, 6v and reference voltage, 4 v are applied to a log-amp with saturation current and temperature compensation. 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 −, $$I_{f}=I_{s} e^{(\frac{V_f}{nV_T})} ......Equation 2$$. This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Log and Antilog Amplifier”. a) In(x) 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. 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