Many uses have been found for Op-amp and an ideal Op-amp seeks to characterize the physical phenomena that make Op-amps useful. Logarithmic Amplifier Objective To design and study a Logarithmic Amplifier using Op-amp Introduction Log amplifier is a linear circuit in which the output voltage will be a constant times the natural logarithm of the input.
These are notable, however, because they determine the maximum voltage the dependent voltage source can output. For any input voltage the ideal Op-amp has, a. Infinite open-loop gain b.
Infinite bandwidth c. Infinite input impedance d. Zero offset voltage e. Infinite slew rate f. Please note that these amplifiers fall under non-linear applications. A logarithmic amplifier , or a log amplifier , is an electronic circuit that produces an output that is proportional to the logarithm of the applied input. This section discusses about the op-amp based logarithmic amplifier in detail. 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.
In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. That means zero volts is applied at the non-inverting input terminal of the op-amp.
According to the virtual short concept , the voltage at the inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal. So, the voltage at the inverting input terminal will be zero volts.
Observe that the left hand side terms of both equation 1 and equation 3 are same. An anti-logarithmic amplifier , or an anti-log amplifier , is an electronic circuit that produces an output that is proportional to the anti-logarithm of the applied input. This section discusses about the op-amp based anti-logarithmic amplifier in detail.
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.
In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. It means zero volts is applied to its non-inverting input terminal. According to the virtual short concept , the voltage at the inverting input terminal of op-amp will be equal to the voltage present at its non-inverting input terminal.
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