A bipolar monolithic analog subsystem for a 4 ½ digit A/D converter

A HIGHLY ACCURATE A/D converter has been required in data handling systems for a microprocessor and in digital multimeters. Responding to this recent demand, a CMOS monolithic structure has been widely employed in combination with the dual slope technique 1,2.. The CMOS process, however, places a limitation on the resolution of an A/D converter at 3 and 1/2 digits. In the dual slope technique, on the other hand, a feedback loop is constructed between the analog and the digital subsystems. This arrangement degrades the electrical isolation between the two systems.