Patent ID: 6507233
Filing Date: 2003-01-14
Classification: G06G

Abstract:
A temperature-compensated monolithic logarithmic amplifier circuit, comprising:(a) a logarithmic amplifier cell configured to produce a logarithmic voltage signal representative of a difference between a first voltage developed across a first PN junction device in response to an input signal and a second voltage developed across a second PN junction device in response to a reference signal; and (b) an output circuit including an output amplifier, a temperature-dependent first resistive element having a positive first temperature coefficient and including interconnection metallization material formed on the monolithic logarithmic amplifier circuit simultaneously with formation of interconnection metallization elsewhere on the monolithic logarithmic amplifier circuit, and a second resistive element having a second temperature coefficient that is of substantially lower magnitude than the first temperature coefficient, the first and second resistive elements being coupled as a voltage divider between an output of the output amplifier and a reference conductor to provide a feedback signal to an input of the output amplifier, the output circuit being configured to produce a temperature-compensated output signal in response to the logarithmic voltage signal, the interconnection metallization material of the first resistive element being configured as a long structure of sufficiently high resistance to temperature-compensate the logarithmic voltage signal.