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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A simple Anti log amplifier is shown below.

Voltage at inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. I edit and author this site. Hence applying KCL at inverting terminal of opamp, we get. Assuming both diode and matched thus material constant, thermal voltage of diode and saturation current of diode is also same. Please note that these amplifiers fall under non-linear applications. Logarithmic amplifier gives the output proportional to the logarithm of input signal.

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.


The circuit arrangement for Antilogarithmic amplifier is illustrated in figure 1.

logarthmic, anti logarthmic amplifiers

Electronic Game and Fun Projects. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input.

So, the voltage at the inverting input terminal will be zero volts. The figure of anti-logarithm amplifier is shown in figure 3.

Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts. Thus, thermal voltage of 1 st transistor will be same to thermal voltage of 2 nd transistor and saturation current antilob 1 st transistor will be equal to saturation current of 2 nd transistor.

Best Arduino Projects 2. V is voltage applied across diode; V t is the map equivalent of temperature. The figure of anti-logarithmic amplifier using matched diode is shown in figure below. Google Plus anyilog Facebook. 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.


Gain of logarithmic amplifier. The output voltage expression becomes.

Since the non inverting terminal of opamp is at ground potential. Anhilog is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal.

This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. Thus we can write. In the circuit shown ampilfier, the non-inverting input terminal of the op-amp is connected to ground. Gain of Anti log amplifier. This section discusses about the op-amp based anti-logarithmic amplifier in detail. So, the voltage aamplifier its inverting input terminal will be zero volts. The logarithmic circuit can be redrawn as follows.

The anti log amplifier can be redrawn as follows.

logarthmic, anti logarthmic amplifiers | ECE Tutorials

An op-amp based logarithmic amplifier produces a voltage o; the output, which is proportional to the logarithm of the voltage applied to the resistor connected to its inverting terminal.

Leave a Reply Cancel reply Your email address will not be published. This section discusses about the op-amp based logarithmic amplifier in detail.