Introduction Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. ❖ It is well known that. 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.

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To design a logarithm amplifier circuit, high ampliifers op-amps like LM, LM, LM are commonly used and a compensated logarithm amplifier may include more than one. Sign up or log in Sign up using Google. In the above circuit, the non-inverting input terminal of the op-amp is connected to ground.

Such circuit techniques are used in integrated log amps: Omitting R1 yields a currentinput log amp. 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. Figure next slide shows the use of a second, matched, transistor for offset compensation and a temperature-dependent gain for gain compensation.

I’m trying to lov an analog multiplier that takes any two voltages and produces the product for them. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts.

It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal. Some integrated log amps have uncommitted elements allowing us to implement antilog amps.

Log And Anti Log Amplifiers

Anti log amplifier is one which provides output proportional to the anti log i. By summing the outputs of two log amplifiers, you get the logarithm of the product of the two original input voltages. Post as a guest Name. They have numerous applications in electronics, such sntilog Since the non inverting terminal of opamp is at ground potential.


Hence applying KCL at inverting terminal of opamp, we get. You can help Wikipedia by expanding it. Sign up using Facebook. Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations.

The source impedance of voltage signals applied to the circuit must be small compared to R1. By using our site, you acknowledge that antliog have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It means zero volts is applied to its non-inverting aamplifiers terminal.

By using this site, you agree to the Terms of Use and Privacy Policy. Consider the voltage-input transdiode. Views Read Edit View history. The final output is developed by an inverting amplifier with a voltage gain of —K2. Constant terms are omitted for simplicity.

Log amplifier

This section discusses about the lob based logarithmic amplifier in detail. This may be ensured by using a rectifier and filter to condition the input signal before applying it to the log amp input.

An op-amp based anti-logarithmic amplifier ampliviers 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 bulk size and Pd rating of the diode affects the thermal resistance and bulk resistance or ESR, and also junction capacitance and bandwidth.

Log and AntiLog Amplifiers

Then, by taking the antilogarithm, you get the product of the two input voltages as indicated in the following equations: IC log amps may cost about ten times the components needed to build a discrete-component log amp. The reverse anitlog current for the diode doubles for every ten degree Celsius rise in temperature. As V in is positive, V out is obliged to be negative since the op amp is in the inverting configuration and is large enough to forward bias the emitter-base junction of the BJT antilob it in the active mode of operation.


The output voltage is expressed as the natural log of the input voltage. To get the logarithm of a signal voltage use a Log amplifier.

Then determines the required input bias current and offset must be to achieve this. Amplifiwrs anti log amplifier can be redrawn as follows. Documents Flashcards Grammar checker.

The current inverter in Figure below uses two matched n-p-n transistors and a precision op amp to achieve accurate current inversion. Very similar question from a month ago: Automated Classification of internet video content. This is the basic layout of the circuit: In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. Home Questions Tags Users Unanswered. I know there is problem with the last stage, the last opamp should give me gain: So, the voltage at its inverting input terminal will be zero volts.

logarthmic, anti logarthmic amplifiers | ECE Tutorials

One usually starts with a spec for Input and Output voltage range and max error vs input. Post Your Answer Discard By clicking “Post Your Amplifiees, you acknowledge that antikog have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. D1 protects the base-emitter junction antillog excessive reverse voltages. An anti-logarithmic amplifieror an anti-log amplifieris an electronic circuit that produces an output that is proportional to the anti-logarithm of the applied input.

Regression-based Active Learning for Fraud Detection. As such, they can vary over a wide range of values. Gain of Anti log amplifier. Leave a Reply Cancel reply Your email address will not be published.

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