A UHF True Logarithmic IF Amplifier

A UHF "true logarithmic IF" which yields a carrier output proportional in amplitude to the logarithm of the carrier input has been constructed. Although this "true" form has been known for a number of years, it appears to have been neglected in development. Good performance has been obtained over a 60-dB input signal range with rise and fall times of 2 ns per 20 dB. A high-level, detected dc coupled output without the use of any dc amplifier is obtained. Coherent signal processing of the output carrier is possible, and other important advantages to this type of logarithmic IF are described.