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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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. 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.

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 anti log amplifier can be redrawn as follows. Google Plus and Facebook. The logarithmic circuit can be redrawn as follows.

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

This section discusses about the op-amp based logarithmic amplifier in detail. The output is depending upon output current of transistor and feedback resistor. Since the non inverting terminal of opamp is at ground potential. You can connect with me on: Leave a Reply Cancel reply Your email address will not be published.

Like logarithmic amplifierantilogarithmic is also a non-linear amplifier.

## Log And Anti Log Amplifiers

It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal. Project Using and 4. The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1. Gain of Anti log amplifier. That means zero volts is applied at the non-inverting input terminal of the op-amp. Two matched diodes are used here, where one diode D 1 is connected in feedback path and second diode D 2 is connected to inverting input of op-amp A2 antulog reverse bias mood as shown in figure 2.

Applying Antilog on both sides we get. Applying KCL at inverting node of opamp we get. You May Also Like.

### Basic Antilog Amplifier Using Diode – EEEGUIDE

Antilogarithmic antiog is one whose output is antilogarithmic exponential of input. This section discusses about the op-amp based anti-logarithmic amplifier in detail.

A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input. The circuit diagram of logarithmic amplifier is as shown below. Hence applying KCL at inverting terminal of opamp, we get. The output voltage expression becomes. In the circuit shown above, the non-inverting input terminal of the op-amp is amplifisr to ground.

It means zero volts is applied to its non-inverting input terminal. Logarithmic amplifier gives the o proportional to the logarithm of input signal. 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.

### Antilogarithmic Amplifier | Derivation

I edit and author this site. Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. Observe that the left hand side terms of both equation 1 and equation 3 are same.

Easy Electronic Projects 5. A simple Anti log amplifier is shown below. Here a general purpose NPN transistor is connected to inverting input of op-amp. Now putting the value of collector current of transistor Antliog C in equation 1. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i. Your antipog address will not be published.

Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts.

Complete Electrical Symbol 3. Anti log amplifier is one which provides output proportional to the anti log i.

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. Thus, we can write.

## logarthmic, anti logarthmic amplifiers

Thus we can write. Two matched transistors is used here as shown in figure, where input is given to usung non-inverting amplifier pin of first op-amplifier A1. Please note that these amplifiers fall under non-linear applications.