The Basic Anti-log Amplifier

The result we get when the base is raised to the power equal to the logarithm of that number is called anti-logarithm of that number.

This particular setup can be formed by connecting the transistor or diode as the input element in contrary to logarithmic amplifier. The exponential formula still applies to base emitter PN junction. The circuit for the anti-logarithmic amplifier is as shown below:

anti-log amplifier using bjt


As in previous case, even diode can be used as the input for anti-logarithmic amplifier, which yields same calculation except for voltage in Vbe.


The main application of logarithmic amplifier is signal compression as said in previous article, while we go in to much detail about it, For handling dynamic range of signals which means the ranges of voltages contained in signal, the signal voltage must be constrained by a process called signal compression, for scaling down a signal if linear circuit is used, even the smaller signal will also be constrained by the same level as like the higher amplitude signals hence logarithmic amplifier serve us as, only option for signal compression because it doesn’t eliminate the lower signals as noise.

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Author: JAY

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