A CMOS bandgap and sub-bandgap voltage reference circuits for nanowatt power LSIs

This paper proposes CMOS bandgap reference (BGR) and sub-BGR circuits without resistors for nanowatt power LSIs. The BGR circuit consists of a nano-ampere current reference, a bipolar transistor, and a proportional to absolute temperature (PTAT) voltage generator. The PTAT voltage generator consists of source-coupled differential pairs and generates a positive temperature dependent voltage. The PTAT voltage generator compensates for negative temperature dependence of a base-emitter voltage in a PNP bipolar transistor. The circuit generates a bandgap voltage of silicon. The sub-BGR circuit uses a voltage divider to generate low-voltage sub-bandgap reference. Experimental results demonstrated that the BGR and sub-BGR circuits can generate a 1.18-V and 553-mV reference voltages, respectively. The power dissipation of the BGR and sub-BGR circuits were 108-nW and 110-nW, respectively.