METHOD AND CIRCUIT FOR COMPENSATING FOR DRIFT INDUCED BY VI IN MONOLITHIC LOGARITHMIC AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To arrange a thermistor for temperature compensation on the same chip as a logarithmic amplifier. SOLUTION: A temperature compensated monolithic logarithmic amplifying circuit is provided with a logarithmic amplifying cell (26) and an output circuit (36). The cell (26) generates a logarithmic voltage signal (V3) showing difference between a first voltage (V1) which corresponds to an input signal (Iin ) and is generated between both ends of a first PN junction device (D1) and a second voltage (V2) which corresponds to a reference signal (Iref ) and is generated between both ends of a second PN junction device (D2). The output circuit (36) includes an output amplifier (19) and a first resistance element (R1) and a second resistance element (R2) which have positive temperature coefficients and depend on a temperature. The output circuit (36) responds to the logarithmic voltage signal (V3) and generates a temperature compensated output signal (Vout ).