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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## logarthmic, anti logarthmic amplifiers

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. Leave a Reply Cancel reply Your email address will not be published. A logarithmic amplifieror a log amplifieris an qntilog circuit that produces an output that is proportional to the logarithm of the applied input. Project Using and 4. Your email address will not be published. The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1.

Antilogarithmic amplifier is one whose opp is antilogarithmic exponential of input.

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 anti-logarithmic amplifier in detail.

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You can connect with me on: Logarithmic amplifier gives the output proportional to the logarithm of input signal. This section discusses about the op-amp based logarithmic amplifier in detail. The figure of anti-logarithm amplifier is shown in figure 3. 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.

Observe that the left hand side terms of both equation 1 and equation 3 are same. It is obvious from the circuit shown above that negative feedback is provided from output to inverting 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.

That means zero volts is applied at the non-inverting input terminal of the amplifirr. Anti log amplifier is one which provides output proportional to the anti usijg i. 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 ahtilog by replying to your comment; Ksing may helps other too.

In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. I edit and author this site. A resistor is connected in feedback path. Electronic Game and Fun Projects.

Thus we can write. 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 anti,og the diode connected to its inverting terminal. 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. Voltage at inverting pin of op-amp A1 is ysing equal to voltage at non-inverting input of op-amp i.

The anti log amplifier can be redrawn as follows. From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i. Gain of Anti log amplifier. Logarithmic hsing operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier.

You May Also Like. Applying KCL at inverting node of opamp we get. Like logarithmic amplifierantioog is also a non-linear amplifier. The circuit diagram of logarithmic amplifier is as shown below. Assuming both diode and matched thus material constant, thermal voltage of diode and saturation current of diode is also same.

Now putting the value of collector current of transistor I C in equation 1.

Best Arduino Projects 2. 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.

### Linear Integrated Circuits Applications Log And Anti Log Amplifiers

Assuming both transistors are matched. So, the voltage at its inverting input terminal will be zero volts. Easy Electronic Projects 5.