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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V is voltage applied across diode; V t is the voltage equivalent of temperature. 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. Please note that these amplifiers fall under non-linear applications.
Antilogarithmic Amplifier | Derivation
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 natilog the diode connected to its inverting terminal. Logarithmic amplifier gives the output proportional to the logarithm of input signal. The figure of anti-logarithm antlog is shown in figure 3.
The figure of anti-logarithmic amplifier using matched diode is shown in figure below. The output is depending upon output current of transistor and feedback resistor. That means zero volts is applied at the non-inverting input terminal of the op-amp. 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.
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This section discusses about the op-amp based anti-logarithmic amplifier in detail. 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inverting pin of op-amp A1 is potentially equal to voltage at non-inverting input of op-amp i. Your email address will not be published. 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. The logarithmic circuit can be redrawn as follows.
logarthmic, anti logarthmic amplifiers | ECE Tutorials
As we know that is very small. Gain of Anti log amplifier. You May Also Like. So, the voltage at the inverting input terminal will be zero volts. Hence applying KCL at inverting terminal of opamp, we get. Thus we can write. The output voltage expression becomes. Here a general purpose NPN transistor is connected to inverting input of op-amp. This section discusses about the op-amp based logarithmic amplifier in detail. Observe usiny the left hand side antllog of both equation 1 and equation 3 are same.
In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. In the above circuit, the non-inverting input terminal of the op-amp is connected to ground.
From the figure we can also conclude that transistor base emitter voltage V BE is equivalent input voltage V i i. Complete Wntilog Symbol 3. Google Plus and Facebook. 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.
A simple Anti log amplifier is shown below.
As we know that. The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm exponential with an amplification are called as Logarithmic usinb and Anti-Logarithmic amplifier respectively.
logarthmic, anti logarthmic amplifiers
So, the voltage at its inverting input terminal will be zero volts. Easy Electronic Projects 5. I edit and author amplifire site. 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.
A resistor is connected in feedback path. 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 ampljfier.
Linear Integrated Circuits Applications Log And Anti Log Amplifiers
The anti log amplifier can be redrawn as follows. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. Best Arduino Projects 2.
Now putting the value of collector current of transistor I C in usinh 1. The circuit diagram of logarithmic amplifier is as shown below. Assuming both transistors are matched. 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. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier.