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 an op-amp will be equal to the voltage at its non-inverting input terminal.

Complete Electrical Symbol 3. Antilogarithmic amplifier is one whose output is antilogarithmic exponential of input. Hence applying KCL at inverting terminal of opamp, we get. 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.

You May Also Like. Like logarithmic amplifierantilogarithmic is also a non-linear amplifier. Since the non inverting terminal of opamp is at ground potential.

I edit and author this site. 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. Project Using and 4. So, the voltage at its inverting input terminal will be zero volts.

As we know that is very small. Thus, we can write. A resistor is connected in feedback path. This section discusses about the op-amp based logarithmic amplifier amplifie detail.

Best Arduino Projects 2. A simple Anti log amplifier is shown below.

### Antilogarithmic Amplifier | Derivation

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. Two matched diodes are used here, usong one diode D 1 is connected in feedback path and second diode D 2 is connected to inverting antilo of op-amp A2 in reverse bias mood as shown in figure 2. Easy Electronic Projects 5.

Logarithmic amplifier gives the output proportional to the logarithm of input signal. So, the voltage at the inverting input terminal will be zero volts. It means zero volts is applied to its non-inverting input terminal. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts. Applying Antilog on both sides we get. You can connect with me on: Observe that the amolifier hand side terms of both equation 1 and equation 3 are same.

Here a general uusing NPN transistor is connected to inverting input of op-amp. Assuming both diode and matched thus material constant, thermal voltage of diode and saturation current of diode is also same.

Google Plus and Facebook. The figure of anti-logarithm amplifier is shown in figure 3. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i.

Applying KCL at inverting node of opamp we get.

## Antilogarithmic Amplifier | Derivation

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. 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.

Leave a Reply Cancel reply Your email address will not be published. The circuit diagram of logarithmic amplifier is amplifisr shown amplifiier. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail.

Assuming both antiloy are matched. This section discusses about the op-amp based anti-logarithmic amplifier in detail. Electronic Game and Fun Projects. 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.

Now putting the value of collector current of transistor I C in equation 1. In the above circuit, the non-inverting input terminal of the op-amp is connected to ground.

The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that usinng proportional to the logarithm of the applied input. The figure of anti-logarithmic amplifier using matched diode is shown in figure below. Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. Your email address will not be published.

Please note that these amplifiers fall under non-linear applications. The output is depending upon output current of transistor and feedback resistor. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier.