LOG100

® LOG100 Precision LOGARITHMIC AND LOG RATIO AMPLIFIER FEATURES q ACCURACY 0.37% FSO max Total Error Over 5 Decades q LINEARITY 0.1% max Log Conformity Over 5 Decades q EASY TO USE Pin-selectable Gains Internal Laser-trimmed Resistors q WIDE INPUT DYNAMIC RANGE 6 Decades, 1nA to 1mA q HERMETIC CERAMIC DIP APPLICATIONS q LOG, LOG RATIO AND ANTILOG COMPUTATIONS q ABSORBANCE MEASUREMENTS q DATA COMPRESSION q OPTICAL DENSITY MEASUREMENTS q DATA LINEARIZATION q CURRENT AND VOLTAGE INPUTS DESCRIPTION The LOG100 uses advanced integrated circuit technologies to achieve high accuracy, ease of use, low cost, and small size. It is the logical choice for your logarithmic-type computations. The amplifier has guaranteed maximum error specifications over the full sixdecade input range (1nA to 1mA) and for all possible combinations of I1 and I2. Total error is guaranteed so that involved error computations are not necessary. The circuit uses a specially designed compatible thinfilm monolithic integrated circuit which contains amplifiers, logging transistors, and low drift thin-film 9 –VCC 1 I1 A1 Q1 Q2 resistors. The resistors are laser-trimmed for maximum precision. FET input transistors are used for the amplifiers whose low bias currents (1pA typical) permit signal currents as low as 1nA while maintaining guaranteed total errors of 0.37% FSO maximum. Because scaling resistors are self-contained, scale factors of 1V, 3V or 5V per decade are obtained simply by pin selections. No other r...