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 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.

Since the non inverting terminal of opamp is at ground potential. Hence applying KCL at inverting terminal of opamp, we get. Now putting the value of collector current of transistor I C in equation 1. Assuming both diode and matched thus material constant, thermal voltage of diode and saturation current of diode is also same.

Gain of logarithmic amplifier. 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. Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i.

Complete Electrical Symbol 3. The logarithmic circuit can be redrawn as follows. Project Using and 4. 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. It means zero volts is applied to its non-inverting input terminal. Gain of Anti log amplifier.

In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. This section discusses about the op-amp based logarithmic amplifier in detail.

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. Applying KCL at inverting node of opamp we get. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier. You can connect with me on: Amolifier, 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.

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### Basic Antilog Amplifier Using Diode – EEEGUIDE

Logarithmic amplifier gives the output proportional to the logarithm of input signal. So, the voltage at its inverting input terminal will be zero volts. Applying Antilog on both sides we get. The circuit diagram of logarithmic amplifier is as shown below.

## logarthmic, anti logarthmic amplifiers

Antilogarithmic amplifier is one whose output is antilogarithmic exponential of input. The figure of anti-logarithmic amplifier using matched diode is shown in figure below. Ampliifier Plus and Facebook.

Here a general uxing NPN transistor is connected to inverting input of op-amp. Thus, we can write. So, the voltage at the inverting input terminal will be zero volts. The figure of anti-logarithm amplifier is shown in figure 3. The output is depending upon output current of transistor and feedback resistor.

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. Electronic Game and Fun Projects.

## Log And Anti Log Amplifiers

Best Arduino Projects 2. As we know that is very small. A simple Anti log amplifier is shown below. Observe that the left hand ahtilog terms of both equation 1 and equation 3 are same.

Thus we apm write. It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal. Your email address will not be published. As we know that. V is voltage applied across diode; V t is the voltage equivalent of temperature.

This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. 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. An antiilog 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.