5.4 A 32nW bandgap reference voltage operational from 0.5V supply for ultra-low power systems

Abstract

Most systems require a voltage reference independent of variation of power supply, process, or temperature, and a bandgap voltage reference (BGR) often serves this purpose. For ultra-low power (ULP) systems, the BGR may constitute a significant component of standby power, and the system start-up voltage is often determined by the voltage, V in , at which the BGR becomes operational. Lowering V in can also allow an ULP system to continue operation longer as its battery or energy harvested input voltage decreases. The minimum V in for state-of-the-art BGRs is restricted by V EB +V DS [1], where V EB is the emitter-base voltage of a pnp transistor, and V DS is the drain-source saturation voltage of a MOS transistor. Recent work brings the V in voltage down to 700mV [2]. There is a need to reduce the standby power and V in of a BGR to increase the lifetime of ULP systems. This paper presents a BGR circuit with measured minimum operating V in of 500mV, reducing the V in of [2] by 1.4×. Further, the power consumption of the proposed circuit is 32nW, which is 1.6× lower than the non-duty cycled BGR reported in [2]. A 2×-charge pump based bandgap core, a switched-capacitor network (SCN), and a current controlled oscillator and clock doubler circuit enable a BGR with a temperature variation of 75ppm/°C and power supply rejection (PSR) of up to -52dB at DC.

A 10 mV-Input Boost Converter With Inductor Peak Current Control and Zero Detection for Thermoelectric and Solar Energy Harvesting With 220 mV Cold-Start and <formula formulatype="inline"><tex Notation="TeX">$-$</tex></formula>14.5 dBm, 915 MHz RF Kick-Start

“…17 shows the implementation of the boost converter where it consumes 0.15 mm . A low power lower voltage bandgap reference circuit which can provide reference voltage from 0.5 V [17] is used for generating the reference voltage for the boost converter. The area of the bandgap reference circuit is 0.03 mm .…”

Voltage reference architectures for low-supply-voltage low-power applications

“…From (16), in order to achieve T I ¼ ðT À T A Þ=2, considering j V th;p;M13 j ¼ 0:45 V and C 2 ¼0.15 pF, the quiescent current, I Q , turns out to be equal to 9 nA.…”

Ultralow power voltage reference circuit for implantable devices in standard CMOS technology

“…[1][2][3][4] The rationale behind BGR is based on the combination of two different voltages, one with proportional-to-absolute temperature (PTAT) characteristics and one with complementary-to-absolute-temperature (CTAT) in order to compensate drain current variations and generate a voltage reference, which is independent of temperature. [1][2][3][4] The rationale behind BGR is based on the combination of two different voltages, one with proportional-to-absolute temperature (PTAT) characteristics and one with complementary-to-absolute-temperature (CTAT) in order to compensate drain current variations and generate a voltage reference, which is independent of temperature.…”

“…Conventional solutions make use of the bandgap voltage reference (BGR) exploiting the existence of parasitic bipolar junction transistors (BJTs) in standard CMOS technologies. [1][2][3][4] The rationale behind BGR is based on the combination of two different voltages, one with proportional-to-absolute temperature (PTAT) characteristics and one with complementary-to-absolute-temperature (CTAT) in order to compensate drain current variations and generate a voltage reference, which is independent of temperature. The main drawback of these approaches is that solutions with reduced power consumption typically require a substantial area overhead or present poor temperature stability.…”