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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It is called four-quadrant since inputs and output can be positive or negative. They have numerous applications in electronics, such as: Automated Classification of internet video content. Unclear what you’re asking.

## Log and AntiLog Amplifiers

The source impedance of voltage signals applied to the circuit must be small compared to R1. So, the voltage at its inverting input terminal will be zero volts.

That means zero volts is applied at the non-inverting input terminal of the op-amp. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Then, by taking the antilogarithm, you get the product of the two input voltages as indicated in the following equations: But if diode current is too low then the OP Amp input offsets become significant compared the the log1, log2 outputs. But this depends on your thermal design.

It is well known that some processes such as multiplication and division, can be performed by addition and subtraction of logs. 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: The current inverter in Figure below uses two matched n-p-n transistors and a precision op amp to achieve accurate current inversion.

Anti log amplifier is one which provides output proportional to the anti log i. Ziad Could this be used to perform division if you used a differential amplifier instead of a summing amplifier? It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal.

The system bandwidth is narrower for small signals because emitter resistance increases for small currents. Logarithmic amplifier gives the output proportional to the logarithm of input signal.

To get the logarithm of a signal voltage use a Log amplifier. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will wntilog zero volts.

### logarthmic, anti logarthmic amplifiers | ECE Tutorials

Constant terms are omitted for simplicity. Sign up using Facebook. 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. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input. Omitting R1 yields a currentinput log amp.

Documents Flashcards Grammar checker. I’m trying to build an analog multiplier that takes any two voltages and produces the product for them. Post as a guest Name. Please note that these amplifiers fall under non-linear applications.

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## logarthmic, anti logarthmic amplifiers

Then finally choose a max temp difference of the log and antilog diodes to avoid gain and offset errors. Email Required, but never shown.

Temperature compensation must correct both error sources. V is voltage applied across diode; V t is the voltage equivalent of temperature. Since the non inverting terminal of opamp is at ground potential.

It means antlog volts is applied to its non-inverting input terminal. Post Your Answer Discard By clicking “Post Your Answer”, you anrilog 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. Alternatively, the log amp can be preceded by a precision current inverter. Then a properly working multiplier should give you 20 volts out. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier.

Leave a Reply Cancel reply Your email address will not be published. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground.

The diode dynamic resistance also drops with rising log current until amplufier where the bulk resistance limits the minimum resistance. Ampllifier Log and antilog amp circuits include the same elements but arranged in different feedback configurations.

Your email address will not be published. IC log amps may cost about ten times the components needed to build a discrete-component log amp. Sign up or log in Sign up using Google. I know there is problem with the last stage, the last opamp should give me gain: This section discusses about the op-amp based logarithmic amplifier in detail.

You have 4 volts and 5 volts as your inputs. 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.

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.

### Linear Integrated Circuits Applications Log And Anti Log Amplifiers

These basic circuits needs additional components to improove the overall performance, i. 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.

Applying Antilog on both sides we get. The two output voltages from the log amplifiers are added and inverted by the unity-gain summing amplifier to produce kog following result: