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 circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1. Since the non inverting terminal of opamp is at ground potential. 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. Thus, thermal voltage of 1 st transistor will be same to thermal voltage ampliffier 2 usijg transistor and saturation current of 1 st transistor will be equal to saturation current of 2 nd transistor.

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Here a general purpose NPN transistor is connected to inverting input of op-amp. You can connect with me on: Thus we can write. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. I edit and author this site. 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.

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From the figure we can also conclude that transistor base emitter anyilog V BE is equivalent input voltage V i i.

### Antilogarithmic Amplifier | Derivation

Now putting the value of collector current of transistor I C in equation 1. The figure of anti-logarithmic amplifier using matched diode anti,og shown in figure below.

You May Also Like. The logarithmic circuit can be redrawn as follows. Like logarithmic amplifierantilogarithmic is also a non-linear amplifier. Applying Antilog on both sides we get.

### logarthmic, anti logarthmic amplifiers | ECE Tutorials

Applying KCL at inverting node of opamp we get. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. 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. This section discusses about the op-amp based anti-logarithmic amplifier in detail.

## logarthmic, anti logarthmic amplifiers

Usung, the voltage at the inverting input terminal will be zero volts. Assuming both diode and matched thus material constant, thermal voltage of diode and saturation current of diode is also same. Hence applying KCL at inverting terminal of opamp, we get. 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 ; kp those purpose please use our comment feature ; We will surely help you by replying to your comment; It may helps other too.

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Google Plus and Facebook. Observe that the left hand side terms of both equation 1 and equation 3 are same. Gain of logarithmic amplifier. Thus, we can write. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input.

The output voltage expression becomes. 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. Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. Electronic Game and Fun Projects.

Easy Electronic Projects 5. The anti log amplifier can be redrawn as follows. A resistor is connected in feedback path. Please note that these amplifiers fall under non-linear applications. Logarithmic amplifier gives the output proportional to the logarithm of input signal.

Anti log amplifier is one which provides output proportional to the anti log i. The output is depending upon output current smplifier transistor and feedback resistor. As we know that. Assuming both transistors are matched. A simple Anti log amplifier is shown below.