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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Gain of logarithmic amplifier. 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 usinb. Applying Antilog on both sides we get. Since the non inverting terminal of opamp is at ground potential.

Logarithmic amplifier gives the output proportional to the logarithm of input signal. Anti log amplifier is one which xmp output proportional to the anti log i.

## Antilogarithmic Amplifier | Derivation

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

The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1. 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.

Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. You can connect with me on: So, the voltage at the inverting input terminal will be zero volts.

### Basic Antilog Amplifier Using Diode – EEEGUIDE

As we know that. Thus we can write. You May Also Like.

This section discusses about the op-amp based anti-logarithmic amplifier in detail. That means zero volts is applied at the non-inverting input terminal of the op-amp. Observe that the usinv hand side terms of both equation 1 and equation 3 are same. 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.

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The figure of anti-logarithmic amplifier using matched diode is shown in figure below. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts.

Best Arduino Projects 2. Electronic Game and Fun Projects. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i. Like logarithmic amplifierantilogarithmic is also a non-linear amplifier. Project Using and 4. The ammplifier diagram of logarithmic amplifier is as shown below.

A simple Anti log amplifier is shown below. V is voltage applied across diode; V t is the voltage equivalent of temperature.

Please note that these amplifiers anntilog under non-linear applications. The anti log amplifier can be redrawn as follows. 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 in reverse bias mood as shown in figure 2. So, the voltage at its inverting input terminal will be zero volts.

## logarthmic, anti logarthmic amplifiers

This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. Easy Electronic Projects 5. According to the virtual short conceptthe voltage at a,p inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal.

The logarithmic circuit can be redrawn as follows. Assuming both transistors are matched. The output is depending upon output current of transistor and feedback resistor. Now putting the value of collector current of transistor I C in equation 1. This section discusses about the op-amp based logarithmic amplifier in detail. 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.

It means zero volts is applied to its non-inverting input terminal. 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. A resistor is connected in feedback path.

I edit and author this site. Here a general purpose NPN transistor is connected to inverting input of op-amp. As we know that is very small. 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.

In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. Gain of Anti log amplifier. It is obvious from the circuit shown above that negative antiolg is provided from anfilog to inverting terminal.