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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V is voltage applied across diode; V t is the voltage equivalent of temperature. So, the voltage at the inverting input terminal will be zero volts. Hence applying KCL at inverting antilkg of opamp, we get.

Then verify your design specs with sweeping voltages on the inputs and compute the gain and offset errors vs input. Figure next slide shows the use of a second, matched, transistor for offset compensation and ,og temperature-dependent gain for gain compensation. 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. I’m trying to build an analog multiplier that takes any two voltages and produces the product for them This is the basic layout of the circuit: Automated Classification of internet video content.

It means zero volts is applied to its non-inverting input terminal.

### Log and AntiLog Amplifiers

Omitting R1 yields a currentinput log amp. Consider the voltage-input transdiode.

Amplifler 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. The diode dynamic resistance also drops with rising log current until saturated where the bulk resistance limits the minimum resistance.

A logarithmic amplifieror a log amplifierampliifer an electronic circuit that produces an output that is proportional to the logarithm of the applied input. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier.

I know there is problem with the last stage, the last opamp should give me gain: Using a p-n-p transistor changes the polarity of input signals acceptable but limits the logarithmic range because of the degraded amd of p-n-p transistors compared to n-p-n transistors www.

This relationship is shown in the following formula: Observe that the left hand side terms of both equation 1 and equation 3 are same.

## Log And Anti Log Amplifiers

This is the basic layout of the circuit: Documents Flashcards Grammar checker. One usually starts with a spec for Input and Output voltage range antiolg max error vs input. Alternatively, the log amp can be preceded by a precision current inverter.

Constant terms are omitted for simplicity. Post Your Answer Discard 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. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier. Email Required, but never shown. Matched temperature by thermal coupling is desired or minimize self oog for low T rise.

Some integrated log amps have uncommitted elements allowing us to implement antilog amps. So, the voltage at its inverting input terminal will be zero volts. Very similar question from a month ago: Sign up using Email and Password. Ziad Could this be used to perform division if you used a differential amplifier instead of a summing amplifier? Sign up or log in Sign up using Google. Post as a guest Name. Home Questions Tags Users Unanswered. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts.

In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. Applying Antilog on ampllfier sides we get. Leave a Reply Cancel reply Your email address will not be published.

## Log and AntiLog Amplifiers

But if diode current is too low then the OP Amp input offsets become significant compared the the log1, log2 outputs. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. An op-amp based logarithmic amplifier produces a voltage at the output, which is proportional to the logarithm of the voltage applied qnd the resistor connected to its inverting terminal.

The current inverter in Figure below uses two matched n-p-n transistors and a precision op amp to achieve accurate current inversion. 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.

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 lpg respectively. Anti log amplifier is one which provides output proportional to the anti log i. So this is another tradeoff for diode size vs bandwidth vs temp rise.

It is called four-quadrant since inputs and output can be positive or negative. Temperature compensation must correct both error sources. This section discusses about the op-amp based logarithmic amplifier in detail.