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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According to the virtual short conceptthe voltage at the inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal. Post Your Answer Lot 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.

DIT offerings in year 3 and 4. The anti log amplifier can be redrawn as follows. Email Required, but never shown.

IC log amps may cost about ten times the components needed to build a discrete-component log amp. Some integrated log amps have uncommitted elements allowing us to implement antilog amps. Matched temperature by thermal coupling is desired or minimize self heating for low T rise.


Log amplifier

It is called four-quadrant since inputs and output can be positive or negative. Then a properly working multiplier should give you 20 volts out.

The logarithmic circuit can be redrawn as follows. Does this seem reasonable? Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier.

Log and AntiLog Amplifiers

I know there is problem with the last stage, the last opamp should give me gain: Constant terms are omitted for simplicity. Anti log amplifier is one which provides output proportional to the anti log i. The output voltage is expressed as the natural log of the input voltage.

The logarithm amplifier gives an output voltage which is proportional to the logarithm of applied input voltage. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts.

Sign up using Facebook. By using our site, you antilgo that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Very similar question from a month ago: Then, by taking the antilogarithm, you get the product of the two input voltages as indicated in the following equations: This page was last edited on 13 Septemberat SPICE simulation of voltage multiplier using log and antilog amplifier.


Similarly the emitter saturation current varies significantly from one transistor to another and also with temperature.

Log amplifier – Wikipedia

This is the basic layout of the circuit: Unclear amplifier you’re asking. 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. The two output voltages from the log amplifiers are added and inverted amplifierz the unity-gain summing amplifier to produce the following result: Hence applying KCL at inverting terminal of opamp, we get.

This relationship is shown in the following formula: Gain of Anti log amplifier. They have numerous applications in electronics, such as: 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.