Log amplifier

A log amplifier is an amplifier for which the output voltage Vout is K times the natural log of the input voltage Vin. This can be expressed as, A log amplifier is an amplifier for which the output voltage Vout is K times the natural log of the input voltage Vin. This can be expressed as, where Vref is the normalization constant in volts and K is the scale factor. The logarithm amplifier gives an output voltage which is proportional to the logarithm of applied input voltage.To design a logarithm amplifier circuit, high performance op-amps like LM1458, LM771, LM714 are commonly used and a compensated logarithm amplifier may include more than one. In some situations, especially in RF domain, monolithic logarithmic amplifiers are also used to reduce number of components and space used, as well improve bandwidth and noise performance.