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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### Basic Antilog Amplifier Using Diode – EEEGUIDE

It means zero volts is applied to its non-inverting input terminal. Anti log amplifier is one which provides output proportional to the anti log i. Gain of Anti log amplifier. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts. 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. Antilogarithmic amplifier is one whose output is antilogarithmic exponential of input.

The circuit diagram of logarithmic amplifier is as shown below. Since the non inverting terminal of opamp is at ground potential. The anti log amplifier can be redrawn as follows. 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. Thus we can write. Gain of logarithmic amplifier. That means zero volts is applied at the non-inverting input terminal of the op-amp.

I edit and author this site. The figure of anti-logarithm amplifier is shown in figure 3.

### Antilogarithmic Amplifier | Derivation

Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. Thus, thermal voltage of 1 st transistor will be same to thermal voltage of natilog nd transistor and saturation current of 1 st transistor will be equal to saturation current of 2 nd transistor. Here a general purpose NPN transistor is connected to inverting input of op-amp.

This section discusses amplifief the op-amp based anti-logarithmic amplifier in detail. You can connect with me on: In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. Best Arduino Projects 2. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i. Observe that the left hand side terms of both equation 1 and equation 3 are same.

## Antilogarithmic Amplifier | Derivation

V is voltage applied across diode; V t is amplifoer voltage equivalent of temperature. Your email address will not be published. Like logarithmic amplifierantilogarithmic is also a non-linear amplifier.

Easy Electronic Projects 5. 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. Applying KCL at inverting node of opamp we get. Hence applying KCL at inverting terminal of ajp, we get. The logarithmic circuit can be redrawn as follows. Applying Antilog on both sides we get.

## logarthmic, anti logarthmic amplifiers

The output is depending upon output current of transistor and feedback resistor. Project Using and 4. Please note that these amplifiers fall under non-linear applications. The figure of anti-logarithmic amplifier using matched diode is shown in figure below.

Google Plus and Facebook. In the above circuit, 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 antliog anti-logarithm of the applied input.

So, the voltage at its inverting input terminal will be zero volts. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier.

Now putting the value of collector current of transistor I C in equation 1. A resistor is connected in feedback path. As we know that is very small. 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.