A Wide Range Logarithmic Amplifier for Nerva

The design of a logarithmic amplifier with an operating range from 10-12 to 10-2 ampere is presented. A logarithmic characteristic within plus or minus 2 per cent of a decade over the 10 decade operating range of the instrument has been realized in the first model. Design improvements being incorporated in a second model include improved transient characteristics and an improved temperature compensation method.