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Antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. The circuit of an antilog amplifier. But if diode current is too low then the OP Amp input offsets become Then finally choose a max temp difference of the log and antilog diodes. EXPERIMENT 8: Log and Antilog Amplifiers. Objectives: To understand the behavior of logarithmic and antilogarithmic amplifiers. Materials and Equipment.

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Log and AntiLog Amplifiers

By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Then determines the required input bias current and offset must be to achieve this. This akplifier discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail.

Email Required, but never shown. This section discusses about the op-amp based anti-logarithmic amplifier in detail. Constant terms are omitted for simplicity. Then, by taking the antilogarithm, you get the product of the two input voltages as indicated in the following equations: The logarithmic circuit can be redrawn as follows.

Very similar question from a month ago: Omitting R1 yields a currentinput log amp. The anti log amplifier can be redrawn as follows. Applying KCL at inverting node of opamp we get.


Alternatively, the log amp can be preceded by a precision current inverter. Your email address will not be published. So this is another tradeoff for diode size vs bandwidth vs temp rise.

Anti log amplifier is one which provides output proportional to the anti log i. Such circuit techniques are used in integrated log amps: So, the voltage at its inverting input terminal will be zero volts. But if diode current is too low then the OP Amp input offsets become significant compared the the log1, log2 outputs.

Regression-based Active Learning for Fraud Detection. Then a properly working multiplier should give you 20 volts out.

Figure next slide shows the use of a second, matched, transistor for offset compensation and a temperature-dependent gain for gain compensation. Temperature compensation can be achieved by the same technique shown for log amps. Home Questions Tags Users Unanswered.

Log And Anti Log Amplifiers

V is voltage applied across diode; V t is the voltage equivalent of temperature. The analysis is the same as above for the transdiode connection, but the logarithmic range is limited to four or five decades because the base current adds to the collector current.

A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input.

A simple Anti log amplifier is shown below.

Log and AntiLog Amplifiers

Documents Flashcards Grammar checker. The two output voltages from the log amplifiers are added and inverted by the unity-gain summing amplifier to produce the following result: IC log amps may cost about ten times the components needed to build a discrete-component log amp.


D1 protects the base-emitter junction from excessive reverse voltages. This is the basic layout of the amplififr Sign up or log in Sign up using Google.

Hence applying KCL at inverting terminal of opamp, we get. You’ve simulated it, so why do you ask if it works for you?

logarthmic, anti logarthmic amplifiers | ECE Tutorials

This relationship anyilog shown in the following formula: Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations. 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.

Gain of Anti log amplifier. Sign up using Email and Password. Leave a Reply Cancel reply Your email address will not be published.

They have numerous applications in electronics, such as: Matched temperature by thermal coupling is desired or minimize self heating for low T rise. I’m trying to abd an analog multiplier that takes any two voltages and produces the product for them.

These basic circuits needs additional components to improove the overall performance, i. Consider the voltage-input transdiode. To investigate its stability, refer to the incremental model, where the BJT has been replaced by its common-base smallsignal model.