A Sub-1V Bandgap Reference Circuit Using Subthreshold Current

Abstract

-A bandgap reference circuit employing subthreshold current is proposed. Only a small fraction of V BE is utilized to generate the reference voltage of 170mV. Since the subthreshold current of MOSFET's is used as the current source, the circuit only consumes 2.4µW at supply voltage of 1V. It was fabricated using 0.18µm CMOS triple-well technology on chip area of 0.029mm 2 . Both of the measurement and the simulation demonstrate the reference voltage variation is 1.3mV from -20°C to 100°C and is 1.1mV per volt for supply voltage from 0.95V to 2.5V. I. INTRODUCTIONThe reference voltage generator is required in many analog and mixed-signal circuits, such as ADC, DAC, DRAM and flash memories, and so forth. It provides a constant reference voltage independent of process, temperature, and supply voltage variation. The bandgap reference (BGR) is the most stable and popular reference voltage generators [1][2]. However, the reference voltage is usually about 1.2V which requires the supply voltage to be over 1.5V, and thus limits the applications at very low supply voltages. Even though many efforts have been done to reduce the reference voltage lower then 1.2V for sub-1V operation [3][4], they required operational amplifiers (OP) which result in larger power consumption, larger chip area and more difficult OP design. The new trend tries to employ the subthreshold characteristics of MOSFET's to generate low reference voltages for sub-1V operation [5][6]. However, due to mobility and threshold voltage variation with temperature and process corners, the reference voltage variation is much larger than the BGR.This work proposes a simple BGR circuit using subthreshold current without OP's for low-power sub-1V operation. The key idea is that a small fraction of V BE in parasitic bipolar transistors and the difference of two V BE 's are combined to generate the reference voltage of 170mV.

A Low-temperature drift bandgap reference circuit with startup enhancement and high currents driving

“…The bandgap reference circuit, as a core circuit in high-precision integrated circuits, can provide an output voltage independent of both the power supply voltage and temperature [1]. With the advancement of integrated circuits, as the process feature size continues to shrink, the demand for high integration and high-performance bandgap reference circuits has become increasingly pressing.…”

Novel Methods for Improved Particle Swarm Optimization in Designing the Bandgap Reference Circuit

“…In this topology, zero-temperature-coefficient (zero-TC) voltage is generated by taking the sum of the proportional-toabsolute-temperature (PTAT) voltage and a complementaryto-absolute-temperature (CTAT) one [2]. However, the Brokaw topology cannot work if the supply voltage is below 1.5 V, and it also cannot generate a reference voltage below 1.2 V [3]. Several sub-1V BGR structures are proposed in [4]- [6] to remedy these problems.…”