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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If you have any comments or suggestions please use our 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. Applying KCL at inverting node of opamp we get. The output voltage expression becomes.

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.

Assuming both diode and matched thus material constant, thermal voltage of diode and saturation current of diode is also same. 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.

As we know that is very small. Google Plus and Facebook. The figure of anti-logarithm amplifier is shown in figure 3. According to the virtual short conceptthe voltage at the inverting input terminal of op-amp will be equal to the voltage present at its non-inverting input terminal. You May Also Like.

Oo Using and 4. Two matched transistors is used here maplifier shown in figure, where input is given to the non-inverting amplifier pin of first op-amplifier A1. Easy Electronic Projects 5. An op-amp based anti-logarithmic amplifier produces a voltage at the output, which usnig proportional to the anti-logarithm of the voltage that is applied to the diode connected to its inverting terminal. Please note that these amplifiers ap under non-linear applications.

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. Thus, thermal voltage of 1 st transistor will be same to thermal voltage of 2 nd transistor and saturation current of 1 st transistor will be equal to saturation current of 2 nd transistor.

Since the non inverting terminal of opamp is at ground potential. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i. You can connect with me on: 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.

### logarthmic, anti logarthmic amplifiers | ECE Tutorials

Anti log amplifier is one which provides output proportional to the anti log i. Observe that the left hand side terms of both equation 1 and equation 3 are same. Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i.

It means zero volts is applied to its non-inverting input terminal. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input. The anti log amplifier can be redrawn as follows. Antilogarithmic amplifier is one whose output is antilogarithmic exponential of input.

So, the voltage at the inverting input terminal will be zero volts. In the above circuit, the non-inverting input terminal of the op-amp is connected to ground.

## Antilogarithmic Amplifier | Derivation

This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. Like logarithmic amplifierantilogarithmic is also a non-linear amplifier. A simple Anti log amplifier is shown below. It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal.

Here a general purpose NPN transistor is connected to inverting input of op-amp.

This section discusses about the op-amp based logarithmic amplifier in detail. I edit and author this site. Applying Antilog on both sides we get.

### Basic Antilog Amplifier Using Diode – EEEGUIDE

Assuming both transistors are matched. Your email address will not be published.

The circuit diagram of logarithmic amplifier is as shown below. Thus, we can write. Now putting the value of collector current of transistor I C in equation 1.

The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1. That means zero volts is applied at the non-inverting input terminal of the op-amp. The logarithmic circuit can be redrawn as follows.

The figure of anti-logarithmic amplifier using matched diode is shown in figure below. Logarithmic amplifier gives the output proportional to the logarithm of input signal. Best Arduino Projects 2. Thus we can write. Hence applying KCL at inverting terminal of opamp, we get.

Complete Electrical Symbol 3. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground.