A 82μW Mixed-Mode sub-1V Bandgap reference with 25 ppm/°C Temperature Co-efficient with Simultaneous PTAT Generation

Conventional voltage mode Bandgap Reference (BGR) output is limited to 1.2V and hence is unsuitable for sub-1V operation in modern CMOS processes. The widely-used current mode BGR (Bamba circuit) provides sub-1V operation, but at the expense of silicon area and losing the PTAT current generation capability. This paper proposes a mixed-mode CMOS bandgap reference circuit, which provides sub-1V bandgap reference, with the PTAT capability, occupying a lower area. In the Bamba circuit, scaled copies of the PTAT current and CTAT current are added to get the zero-temperature coefficient, whereas in the proposed technique, CTAT voltage and PTAT current are suitably added. Self-bias techniques are utilized wherever possible to minimize the temperature drift of the systematic offset. A prototype designed in 65nm CMOS technology for a nominal voltage of 742mV demonstrates 25 ppm/°C temperature coefficient from −40°C to 125°C. The circuit draws 82uW power from a 1V power supply.