集成对数放大器的工业应用

集成对数放大器的工业应用:Integrated logarithmic amplifiers for industrial applications

Many industrial applications measure physical quantities

over a wide dynamic range. These applications use logarithmic

amplifiers (log amps) to match a transmitter’s

dynamic output to the linear input range of a signal gauge.

Figure 1 shows a typical signal chain to measure photo

currents over a dynamic range of seven decades.

Log amps of the past were built with hybrid techniques.

Today’s CMOS technology enables the integration of the logging

circuit and additional support functions, such as voltage

references and uncommitted op amps, into a single chip.

This article describes the operation and architecture of

integrated log amps and provides two application examples

using the Texas Instruments (TI) LOG112 and LOG2112.