a diode used in the feedback loop of an operational amplifier is forward biased by a constant current loop of an op-amp. Antilog is inverse operation of log operation so; antilog amplifiers can be operation. Log Amplifier using Diode. Fig 1. Antilogarithmic Amplifier using Single Transistor. The circuit Here a general purpose NPN transistor is connected to inverting input of op-amp. Basic Antilog Amplifier Using Diode The circuit diagram of basic antilog amplifier using diode As op-amp input current is zero, the current I must be same as If.

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The anti log amplifier can be redrawn as follows. Applying KCL at inverting node of opamp we get. So, the voltage at the inverting input terminal will be zero volts. Here a general purpose NPN transistor is connected to inverting input of op-amp.

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. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier. Logarithmic amplifier gives the output proportional to the logarithm of input signal.

Applying Antilog on both sides we get.

V is voltage applied across diode; V t is the voltage equivalent of temperature. As we know that. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts. The output voltage expression becomes.

Gain of logarithmic amplifier. 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. 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. This section discusses about the op-amp based anti-logarithmic amplifier in detail.

Easy Electronic Projects 5. Thus we can write. So, the voltage at its inverting input terminal will be zero volts. If you have any comments or suggestions please use smp contact page We strictly ignore emails regarding post helps or explanation of circuits and projects ; for those purpose please use our comment feature ; We will surely help you by replying to your comment; It may helps other too.

Anti log amplifier is one which provides output proportional to the anti log i. Electronic Game and Fun Projects. Thus, we can write. As ap know that is very small. The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1.

Assuming both transistors are matched. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail.

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

A amplififr is connected in feedback path. Observe that the left hand side terms of both equation 1 and equation 3 are same. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i.

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Antilogarithmic amplifier is one whose output is antilogarithmic exponential of input. Best Arduino Projects 2. Complete Electrical Symbol 3. Like logarithmic amplifierantilogarithmic is also a non-linear amplifier. This section discusses about the op-amp based logarithmic amplifier in detail. It means zero volts is applied to its non-inverting input terminal. A simple Anti log amplifier is shown below. Since the non inverting terminal of opamp is at ground potential.

Please note that these amplifiers amplifjer under non-linear applications. Hence applying KCL at inverting terminal of opamp, we get. I edit and author this site. That means zero volts is applied at the non-inverting input terminal of the op-amp. Two matched transistors is used here as shown in figure, where input is given to the non-inverting amplifier pin of first op-amplifier A1.

You can connect with me on: 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. The figure of anti-logarithmic amplifier using matched diode is shown in figure below.

It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal.

## Antilogarithmic Amplifier | Derivation

You May Also Like. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input. The logarithmic circuit can be redrawn as follows.