It is reported that a 5 pico amps bias current and ″zero″ offset voltage FET input operational amplifier has been realized by combining in a TO-99 package (741 pin configuration), two monolithic chips with a thin film resistor network. The two monolithic devices consist of a dual FET chip and a modified ″741 type″ operational amplifier. The two chip approach was chosen over the single chip technique where the FETs are integrated with the bipolar op amp to optimize the overall performance and retain flexibility. By manufacturing the FET and bipolar devices separately, the processing steps can be tailored to achieve the highest performance without compromise.
