An Improved CMOS Voltage Bandgap Reference Circuit
01 Jan 2018-pp 621-629
TL;DR: In this paper, the authors proposed a bandgap reference circuit with PTAT generation by avoiding the need of start-up circuit and assumption made for PTAT as strong forward bias, which showed low temperature coefficient, high accuracy in output voltage, and temperature is varied from −20 to 200 ppm/°C with 1.8 V supply voltage.
Abstract: Bandgap Reference (BGR) circuit plays a vital role in analog and digital circuit design. BGRs provide temperature-insensitive reference voltages subject to silicon bandgap (1.2 eV). Implementation of BGR circuit zero temperature coefficient (TC) by using P–N diodes and making temperature independent by combining proportional to absolute temperature (PTAT) and complimentary to absolute temperature (CTAT) voltages. PTAT generation and start-up circuits are the two basic elements of BGR to anticipate in nano-watt applications. Start-up circuit requires for PTAT to avoid undesirable zero bias condition. The start-up circuit consists a potential divider with resistors between supply rails. The DC current flows through a resistance path which is larger than leakage current to make the start-up circuit in stable operation. This work proposes bandgap reference circuit with PTAT generation by avoiding the need of start-up circuit and assumption made for PTAT as strong forward bias. This simulation is carried with cadence environment in UMC 180 nm technology. This proposed work results show low temperature coefficient, high accuracy in output voltage, and temperature is varied from −20 to 200 ppm/°C with 1.8 V supply voltage.
Citations
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10 Jun 2021
TL;DR: In this article, a self-bias opamp has been exploited to minimize the systematic offset in conventional BGR circuits, and a current mirror-assisted technique has been proposed to enable BGR operational at 0.82-1.05V supply without having any degradation in the performance while keeping the integrated noise of 15.2µV and accuracy of 23.4ppm/°C.
Abstract: Traditional BGR circuits require a 1.05V supply due to the V BE of the BJT. Deep submicron CMOS technologies are limiting the supply voltage to less than 940mV. Hence there is a strong motivation to design them at lower supply voltages. The supply voltage limitation in conventional BGR is described qualitatively in this paper. Further, a current mirror-assisted technique has been proposed to enable BGR operational at 0.82V supply. A prototype was developed in 65nm TSMC CMOS technology and post-layout simulation results were performed. A self-bias opamp has been exploited to minimize the systematic offset. Proposed BGR targeted at 450mV works from 0.82-1.05V supply without having any degradation in the performance while keeping the integrated noise of 15.2µV and accuracy of 23.4ppm/°C. Further, the circuit consumes 21µW of power and occupies 73*32µm2silicon area.
15 citations
References
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07 Feb 2017
TL;DR: This paper presents a sub-10nW bandgap-reference (BGR) circuit that implements both voltage and current references in one circuit, and tries to make the exponential term in the subthreshold current equation constant or temperature-independent, hence reducing process and temperature dependencies.
Abstract: Ultra-low-power (ULP) sensor technologies for the future internet of things have presented challenges in ULP implementation of reference circuits while keeping traditional requirements of stable performance. For voltage reference circuits, as an essential block in SoCs to generate various internal supply voltages, the bandgap voltage-reference (BGVR) scheme has been widely used since it provides a well-defined value with strong immunity to process/voltage/temperature variations. Nanowatt-consuming BGVR circuits have been recently proposed using a capacitor network [4] and a leakage-based proportional-to-absolute-temperature (PTAT) circuit [5]. On the other hand, the current reference circuit that is required to set internal bias current still presents difficulties in achieving both stable performance and ULP consumption. The general approach to building a current reference is to use a BGVR with additional resistors for V-to-I conversion. Though it can provide a well-defined stable current reference, it also requires excessively large resistance for ULP consumption. Another approach is a CMOS-based current reference circuit that tries to make the exponential term in the subthreshold current equation constant or temperature-independent, hence reducing process and temperature dependencies. While CMOS reference circuits have achieved ULP implementations, the current is still determined by a number of process and design parameters, resulting in large sensitivity to process variations. This paper presents a sub-10nW bandgap-reference (BGR) circuit that implements both voltage and current references in one circuit. The BGR circuit is implemented with a 0.18µm CMOS process and generates voltage and a current references of 1.238V and 6.64nA while consuming 9.3nW. The voltage and current references show standard deviations of 0.43% and 1.19% with temperature coefficients of 26ppm/°C and 283ppm/°C, respectively.
77 citations
19 Mar 2015
TL;DR: Though the BGR provides a robust voltage or current reference with insensitivity to process, voltage and temperature variations that is superior to CMOS-only reference circuits, it has received little attention in ultra-low-power (ULP) sensor applications.
Abstract: Bandgap references (BGRs) are widely used to generate a temperature-insensitive reference voltage determined by the silicon bandgap. the BGR generally utilizes PN diodes to generate both of proportional-to-absolute-temperature (PTAT) and complementary-to-absolute-temperature (CTAT) quantities and combines them to eliminate the temperature dependency. Though the BGR provides a robust voltage or current reference with insensitivity to process, voltage and temperature variations that is superior to CMOS-only reference circuits, it has received little attention in ultra-low-power (ULP) sensor applications. While CMOS-only reference circuits have recently demonstrated nanowatt power consumption [1], BGR approaches still have two critical factors to preventing nanowatt consumption. One is that PTAT generation assumes sufficient forward bias, VD, of the PN junction to allow eVD/(n·VT) to be much larger than 1 in the temperature range of interest, where n and VT (=kT/q) represent the ideality factor and the thermal voltage, respectively. In addition, the PTAT generation requires a start-up circuit to prevent the circuit from resting at the undesirable zero-bias condition. Since the start-up circuit utilizes a resistive voltage division between power rails, it consumes non-zero DC current, which must be larger than leakage current in order to ensure stable start-up operation. These two requirements for PTAT generation limit the use of BGRs in nanowatt ULP applications.
38 citations
18 Jul 2010
TL;DR: A high-performance CMOS band-gap reference (BGR) is designed in this paper, in which a three-stage operational amplifier is adopted to get high PSRR and only first-order temperature compensation technology is employed to get a low temperature coefficient.
Abstract: A high-performance CMOS band-gap reference (BGR) is designed in this paper. The proposed circuit employs the current-mode architecture optimized for low supply voltage applications. The key portion of the circuit employs the Brokaw BGR architecture, in which a three-stage operational amplifier is adopted to get high PSRR and only first-order temperature compensation technology is employed to get a low temperature coefficient. The circuit is on the Chartered 0.18 μ m CMOS process under the operating voltage of 1.8V and its simulation results are presented. The simulation results show that the temperature coefficient is 9 ppm/°K over the −40°C to 125°C temperature range and the fluctuation of reference voltage is within 0.067m V when the power voltage changes from 1.44V to 2.16V. In addition, the PSRR is 108.5dB at 10 kHz, and the power consumption is only 0.355mW1
10 citations
11 Oct 2012
TL;DR: A high precision band-gap reference (BGR) with piecewise-linear compensation is designed in this paper and a high gain, low power supply rejection ratio (PSRR) operational amplifier is designed to improve the PSRR of the band- gap reference.
Abstract: A high precision band-gap reference (BGR) with piecewise-linear compensation is designed in this paper. A low voltage Brokaw BGR architecture is employed to provide low output voltage. A high gain, low power supply rejection ratio (PSRR) operational amplifier is designed to improve the PSRR of the band-gap reference. In order to achieve temperature stability significantly lower than the traditional band-gap reference, a circuit which produces a current with positive temperature coefficient (TC) at high temperatures and 0 current at lower temperatures is designed. The whole BGR circuits are simulated by Spectre based on chartered 0.18μm 1P5M 1.8V CMOS technology. It's clear from simulation result that the TC of the output reference voltage approaches 2.61ppm/K over the military temperature range, the PSRR reaches 107.2dB at low frequency (f=0.1HZ), the whole BGR dissipates 0.4mW. In addition, the output reference voltage changes only 8.6μV when the power supply changes from 1.5V to 2.1V, that is to say, the power regulation ratio is 0.014mV/V.
8 citations