A 82μW Mixed-Mode sub-1V Bandgap reference with 25 ppm/°C Temperature Co-efficient with Simultaneous PTAT Generation
T. S. S. Varun, R. Nagulapalli, Immanuel Raja
Abstract
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.