### ANTILOG AMPLIFIER USING OP AMP PDF

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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I edit and author this site. 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.

Hence applying KCL at inverting terminal of opamp, we get.

Your email address will not be published. As we know antiolg. You can connect with me on: Please note that these amplifiers fall under non-linear applications.

V is voltage applied across diode; V t is the voltage equivalent of temperature. Electronic Game and Fun Projects. The output is depending upon output current of transistor and feedback resistor.

### Basic Antilog Amplifier Using Diode – EEEGUIDE

The logarithmic circuit can be redrawn as follows. According to the virtual short conceptthe voltage at the inverting input terminal of an uaing will be equal to the voltage at its non-inverting input terminal. A simple Anti log amplifier is shown below.

From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i.

Thus, thermal voltage of 1 st transistor will be same to thermal voltage pp 2 nd transistor and saturation current of 1 st transistor will be equal to saturation current of 2 nd transistor. Observe that the left hand side terms of both equation 1 and equation 3 are same.

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. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier. Logarithmic amplifier gives the output proportional to the logarithm of input signal.

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 ampllfier. Complete Electrical Symbol 3. The figure of anti-logarithmic amplifier using matched diode is shown in figure below. Thus we can write. 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 usig.

Assuming both transistors are matched. 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.

## Log And Anti Log Amplifiers

So, the voltage at antiloog inverting input terminal will be zero volts. In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. Gain of logarithmic amplifier. Antilogarithmic amplifier is one whose output is antilogarithmic exponential of input. A resistor is connected in feedback path.

Here a general purpose NPN transistor is connected to inverting input of op-amp. Using the concept of virtual short between the ampligier terminals of an opamp the voltage at inverting terminal will be zero volts.

As we know that is very small. 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. Best Arduino Projects 2. So, the voltage at the inverting input terminal will be zero volts. This section discusses about the op-amp based anti-logarithmic amplifier in detail.

Antiloog figure of anti-logarithm amplifier is shown in figure 3.

The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. The anti log am; can be redrawn as follows. Google Plus and Facebook.