# A Low-Power CMOS Bandgap Voltage Reference for Supply Voltages Down to 0.5 V

^{*}

## Abstract

**:**

## 1. Introduction

## 2. LV Bandgap Voltage Reference

#### 2.1. MOSFET-Based Voltage Reference

#### 2.2. Proposed BG Core

#### 2.3. Offset and Noise Contribution of the Amplifier

## 3. Prototype Design

#### 3.1. Start-Up Circuit

#### 3.2. Device Sizing

## 4. Results

^{2}. All tests were performed with ${V}_{dd}$ = 0.5 V, T = 27 °C, and ${f}_{clk}$ = 100 kHz, unless otherwise specified.

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

- Qiu, S.; Wang, Z.; Zhao, H.; Hu, H. Using Distributed Wearable Sensors to Measure and Evaluate Human Lower Limb Motions. IEEE Trans. Instrum. Meas.
**2016**, 65, 939–950. [Google Scholar] [CrossRef] [Green Version] - Selvam, A.P.; Muthukumar, S.; Kamakoti, V.; Prasad, S. A wearable biochemical sensor for monitoring alcohol consumption lifestyle through Ethyl glucuronide (EtG) detection in human sweat. Sci. Rep.
**2016**, 6, 1–11. [Google Scholar] [CrossRef] - Saraereh, O.A.; Alsaraira, A.; Khan, I.; Choi, B.J. A Hybrid Energy Harvesting Design for On-Body Internet-of-Things (IoT) Networks. Sensors
**2020**, 20, 407. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Lo Presti, D.; Carnevale, A.; D’Abbraccio, J.; Massari, L.; Massaroni, C.; Sabbadini, R.; Zaltieri, M.; Di Tocco, J.; Bravi, M.; Miccinilli, S.; et al. A Multi-Parametric Wearable System to Monitor Neck Movements and Respiratory Frequency of Computer Workers. Sensors
**2020**, 20, 536. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Bariya, M.; Nyein, H.Y.Y.; Javey, A. Wearable sweat sensors. Nat. Electron.
**2018**, 1, 160–171. [Google Scholar] [CrossRef] - Dei, M.; Aymerich, J.; Piotto, M.; Bruschi, P.; del Campo, F.J.; Serra-Graells, F. CMOS Interfaces for Internet-of-Wearables Electrochemical Sensors: Trends and Challenges. Electronics
**2019**, 8, 150. [Google Scholar] [CrossRef] [Green Version] - Oktavius, A.K.; Gu, Q.; Wihardjo, N.; Winata, O.; Sunanto, S.W.; Li, J.; Gao, P. Fully-Conformable Porous Polyethylene Nanofilm Sweat Sensor for Sports Fatigue. IEEE Sens. J.
**2021**, 21, 8861–8867. [Google Scholar] [CrossRef] - Wang, H.; Wang, G.; Ling, Y.; Qian, F.; Song, Y.; Lu, X.; Chen, S.; Tong, Y.; Li, Y. High power density microbial fuel cell with flexible 3D graphene–nickel foam as anode. Nanoscale
**2013**, 5, 10283–10290. [Google Scholar] [CrossRef] - Talkhooncheh, A.H.; Yu, Y.; Agarwal, A.; Kuo, W.W.T.; Chen, K.C.; Wang, M.; Hoskuldsdottir, G.; Gao, W.; Emami, A. A Biofuel-Cell-Based Energy Harvester With 86% Peak Efficiency and 0.25-V Minimum Input Voltage Using Source-Adaptive MPPT. IEEE J. Solid-State Circuits
**2021**, 56, 715–728. [Google Scholar] [CrossRef] - Tanwar, A.; Lal, S.; Razeeb, K.M. Structural Design Optimization of Micro-Thermoelectric Generator for Wearable Biomedical Devices. Energies
**2021**, 14, 2339. [Google Scholar] [CrossRef] - Khan, S.; Kim, J.; Roh, K.; Park, G.; Kim, W. High power density of radiative-cooled compact thermoelectric generator based on body heat harvesting. Nano Energy
**2021**, 87, 106180. [Google Scholar] [CrossRef] - Proto, A.; Vondrak, J.; Schmidt, M.; Kubicek, J.; Gorjani, O.M.; Havlik, J.; Penhaker, M. A Flexible Thermoelectric Generator Worn on the Leg to Harvest Body Heat Energy and to Recognize Motor Activities: A Preliminary Study. IEEE Access
**2021**, 9, 20878–20892. [Google Scholar] [CrossRef] - Alioto, M. Enabling the Internet of Things: From Integrated Circuits to Integrated Systems; Springer: New York, NY, USA, 2017. [Google Scholar] [CrossRef]
- Widlar, R. New developments in IC voltage regulators. IEEE J. Solid-State Circuits
**1971**, 6, 2–7. [Google Scholar] [CrossRef] [Green Version] - Kuijk, K.E. A precision reference voltage source. IEEE J. Solid-State Circuits
**1973**, 8, 222–226. [Google Scholar] [CrossRef] - Kok, C.W.; Tam, W.S. CMOS Voltage References: An Analytical and Practical Perspective; John Wiley & Sons: Hoboken, NJ, USA, 2012. [Google Scholar] [CrossRef]
- Ferro, M.; Salerno, F.; Castello, R. A floating CMOS bandgap voltage reference for differential applications. IEEE J. Solid-State Circuits
**1989**, 24, 690–697. [Google Scholar] [CrossRef] - Banba, H.; Shiga, H.; Umezawa, A.; Miyaba, T.; Tanzawa, T.; Atsumi, S.; Sakui, K. A CMOS bandgap reference circuit with sub-1-V operation. IEEE J. Solid-State Circuits
**1999**, 34, 670–674. [Google Scholar] [CrossRef] [Green Version] - Malcovati, P.; Maloberti, F.; Fiocchi, C.; Pruzzi, M. Curvature-compensated BiCMOS bandgap with 1-V supply voltage. IEEE J. Solid-State Circuits
**2001**, 36, 1076–1081. [Google Scholar] [CrossRef] [Green Version] - Boni, A. Op-amps and startup circuits for CMOS bandgap references with near 1-V supply. IEEE J. Solid-State Circuits
**2002**, 37, 1339–1343. [Google Scholar] [CrossRef] [Green Version] - Sanborn, K.; Ma, D.; Ivanov, V. A Sub-1-V Low-Noise Bandgap Voltage Reference. IEEE J. Solid-State Circuits
**2007**, 42, 2466–2481. [Google Scholar] [CrossRef] - Ivanov, V.; Brederlow, R.; Gerber, J. An Ultra Low Power Bandgap Operational at Supply From 0.75 V. IEEE J. Solid-State Circuits
**2012**, 47, 1515–1523. [Google Scholar] [CrossRef] - Chi-Wa, U.; Zeng, W.L.; Law, M.K.; Lam, C.S.; Martins, R.P. A 0.5-V Supply, 36 nW Bandgap Reference With 42 ppm/°C Average Temperature Coefficient Within -40 °C to 120 °C. IEEE Trans. Circuits Syst. I Regul. Pap.
**2020**, 67, 3656–3669. [Google Scholar] [CrossRef] - Tzanateas, G.; Salama, C.; Tsividis, Y. A CMOS bandgap voltage reference. IEEE J. Solid-State Circuits
**1979**, 14, 655–657. [Google Scholar] [CrossRef] - Vittoz, E.; Neyroud, O. A low-voltage CMOS bandgap reference. IEEE J. Solid-State Circuits
**1979**, 14, 573–579. [Google Scholar] [CrossRef] - Giustolisi, G.; Palumbo, G.; Criscione, M.; Cutri, F. A low-voltage low-power voltage reference based on subthreshold MOSFETs. IEEE J. Solid-State Circuits
**2003**, 38, 151–154. [Google Scholar] [CrossRef] - Zhuang, H.; Zhu, Z.; Yang, Y. A 19-nW 0.7-V CMOS Voltage Reference with No Amplifiers and No Clock Circuits. IEEE Trans. Circuits Syst. II Express Briefs
**2014**, 61, 830–834. [Google Scholar] [CrossRef] - Yang, Y.; Binkley, D.M.; Li, L.; Gu, C.; Li, C. All-CMOS subbandgap reference circuit operating at low supply voltage. In Proceedings of the 2011 IEEE International Symposium of Circuits and Systems (ISCAS), Rio de Janeiro, Brazil, 15–18 May 2011; pp. 893–896. [Google Scholar] [CrossRef]
- Yang, B.D. 250-mV Supply Subthreshold CMOS Voltage Reference Using a Low-Voltage Comparator and a Charge-Pump Circuit. IEEE Trans. Circuits Syst. II Express Briefs
**2014**, 61, 850–854. [Google Scholar] [CrossRef] - Blauschild, R.; Tucci, P.; Muller, R.; Meyer, R. A new NMOS temperature-stable voltage reference. IEEE J. Solid-State Circuits
**1978**, 13, 767–774. [Google Scholar] [CrossRef] - De Vita, G.; Iannaccone, G. A Sub-1-V, 10 ppm/°C, Nanopower Voltage Reference Generator. IEEE J. Solid-State Circuits
**2007**, 42, 1536–1542. [Google Scholar] [CrossRef] - Dong, Q.; Yang, K.; Blaauw, D.; Sylvester, D. A 114-pW PMOS-only, trim-free voltage reference with 0.26% within-wafer inaccuracy for nW systems. In Proceedings of the 2016 IEEE Symposium on VLSI Circuits (VLSI-Circuits), Honolulu, HI, USA, 15–17 June 2016; pp. 1–2. [Google Scholar] [CrossRef]
- Fassio, L.; Lin, L.; De Rose, R.; Lanuzza, M.; Crupi, F.; Alioto, M. Trimming-Less Voltage Reference for Highly Uncertain Harvesting Down to 0.25 V, 5.4 pW. IEEE J. Solid-State Circuits
**2021**. [Google Scholar] [CrossRef] - Bruschi, P.; Catania, A.; Del Cesta, S.; Piotto, M. A Two-Stage Switched-Capacitor Integrator for High Gain Inverter-Like Architectures. IEEE Trans. Circuits Syst. II Express Briefs
**2020**, 67, 210–214. [Google Scholar] [CrossRef] - Del Cesta, S.; Ria, A.; Simmarano, R.; Piotto, M.; Bruschi, P. A compact programmable differential voltage reference with unbuffered 4 mA output current capability and ±0.4% untrimmed spread. In Proceedings of the ESSCIRC 2017—43rd IEEE European Solid State Circuits Conference, Leuven, Belgium, 11–14 September 2017; pp. 11–14. [Google Scholar] [CrossRef]
- Ria, A.; Catania, A.; Cicalini, M.; Benvenuti, L.; Piotto, M.; Bruschi, P. A Sub-1V CMOS Switched Capacitor Voltage Reference with high output current capability. In Proceedings of the 2019 15th Conference on Ph.D Research in Microelectronics and Electronics (PRIME), Lausanne, Switzerland, 15–18 July 2019; pp. 9–12. [Google Scholar] [CrossRef]
- Enz, C.C.; Krummenacher, F.; Vittoz, E.A. An analytical MOS transistor model valid in all regions of operation and dedicated to low-voltage and low-current applications. Analog Integr. Circuits Signal Process.
**1995**, 8, 83–114. [Google Scholar] [CrossRef] - Enz, C.C.; Vittoz, E.A. Charge-Based MOS Transistor Modeling: The EKV Model for Low-Power and RF IC Design; John Wiley & Sons: Hoboken, NJ, USA, 2006. [Google Scholar] [CrossRef]
- Majumder, S.; Mondal, T.; Deen, M.J. Wearable Sensors for Remote Health Monitoring. Sensors
**2017**, 17, 130. [Google Scholar] [CrossRef] - Magnelli, L.; Crupi, F.; Corsonello, P.; Pace, C.; Iannaccone, G. A 2.6 nW, 0.45 V Temperature-Compensated Subthreshold CMOS Voltage Reference. IEEE J. Solid-State Circuits
**2011**, 46, 465–474. [Google Scholar] [CrossRef] - Wang, Y.; Zhu, Z.; Yao, J.; Yang, Y. A 0.45-V, 14.6-nW CMOS Subthreshold Voltage Reference With No Resistors and No BJTs. IEEE Trans. Circuits Syst. II Express Briefs
**2015**, 62, 621–625. [Google Scholar] [CrossRef]

**Figure 1.**Schematic view of (

**a**) the bandgap reference voltage proposed in [15] and (

**b**) its all-MOSFET version.

**Figure 2.**Temperature behavior of $\Delta {V}_{GS}$ (

**a**) and ${V}_{ref}$ (

**b**) in the BG core of Figure 1b, for different values of ${V}_{th}$, considering or neglecting the ${V}_{DS}$ effect on the drain current.

**Figure 3.**Schematic view of (

**a**) the proposed bandgap reference voltage and (

**b**) its equivalent small signal circuit.

**Figure 4.**Temperature behavior of ${V}_{ref}$ and $\Delta {V}_{GS}$ in the BG core of Figure 3a, for ${V}_{dd}=0.5$ V, considering or neglecting the ${V}_{DS}$ effect on the drain current, for ${V}_{th}=110$ mV (

**a**) and ${V}_{th}=50$ mV (

**b**).

**Figure 5.**Supply voltage dependence of ${V}_{ref}$ (at $T={T}_{0}$) and the Temperature Coefficient (TC), considering or neglecting the ${V}_{DS}$ effect on the drain current.

**Figure 8.**Micrograph of the proposed voltage reference with the layout aligned and superimposed in order to show the devices and interconnections that would be otherwise hidden below the planarization dummies. The dimensions and the main blocks are indicated.

**Figure 9.**Measured output voltage, ${V}_{ref}$, as a function of the power supply at room temperature.

Device | Type | W ($\mathsf{\mu}$m) | L ($\mathsf{\mu}$m) | m |
---|---|---|---|---|

${\mathrm{M}}_{1}$ | LVT | 3 | 3 | 1 |

${\mathrm{M}}_{2}$ | LVT | 3 | 3 | 5 |

${\mathrm{M}}_{3}$ | ZVT | 3.5 | 0.35 | 4 |

${\mathrm{M}}_{4}$ | RVT | 1.8 | 0.18 | 2 |

${\mathrm{M}}_{5}$ | ZVT | 0.5 | 0.5 | 1 |

${\mathrm{M}}_{6}$ | RVT | 3 | 3 | 10 |

${\mathrm{M}}_{\mathrm{I}1\mathrm{n}}$ | RVT | 2 | 2 | 1 |

${\mathrm{M}}_{\mathrm{I}1\mathrm{p}}$ | RVT | 2 | 2 | 4 |

${\mathrm{M}}_{\mathrm{I}2\mathrm{n}}$ | RVT | 2 | 2 | 1 |

${\mathrm{M}}_{\mathrm{I}2\mathrm{p}}$ | RVT | 2 | 2 | 4 |

${\mathrm{M}}_{\mathrm{I}3\mathrm{n}}$ | RVT | 2 | 2 | 1 |

${\mathrm{M}}_{\mathrm{I}3\mathrm{p}}$ | RVT | 2 | 2 | 4 |

${\mathrm{M}}_{\mathrm{I}4\mathrm{n}}$ | RVT | 0.28 | 0.18 | 1 |

${\mathrm{M}}_{\mathrm{I}4\mathrm{p}}$ | RVT | 0.28 | 0.18 | 4 |

${\mathrm{M}}_{\mathrm{I}5\mathrm{n}}$ | RVT | 0.28 | 0.18 | 1 |

${\mathrm{M}}_{\mathrm{I}5\mathrm{p}}$ | RVT | 0.28 | 0.18 | 4 |

Device | Value | Device | Value |
---|---|---|---|

${\mathrm{R}}_{1}$ | 616 k$\mathsf{\Omega}$ | ${\mathrm{C}}_{\mathrm{T}}$ | 1 pF |

${\mathrm{R}}_{2}$ | 616 k$\mathsf{\Omega}$ | ${\mathrm{C}}_{\mathrm{F}}$ | 1 pF |

${\mathrm{R}}_{\mathrm{T}}$ | 154 k$\mathsf{\Omega}$ | ${\mathrm{C}}_{\mathrm{H}}$ | 1 pF |

${\mathrm{C}}_{\mathrm{S}}$ | 1 pF | ${\mathrm{C}}_{\mathrm{SU}}$ | 200 fF |

This Work | [22] | [40] | [23] | [41] | [29] | [33] | [27] | |
---|---|---|---|---|---|---|---|---|

Technology (nm) | 180 | 130 | 180 | 65 | 180 | 110 | 180 | 180 |

Power (nW) | 315 | 170 | 2.6 | 38 | 14 | 5.35 $\times \phantom{\rule{3.33333pt}{0ex}}{10}^{3}$ | 5.4 $\times \phantom{\rule{3.33333pt}{0ex}}{10}^{-3}$ | 19 |

${V}_{dd-min}$ (V) | 0.5 | 0.75 | 0.45 | 0.5 | 0.45 | 0.242 | 0.25 | 0.7 |

${V}_{ref}$ (V) | 0.233 | 0.256 | 263.5 | 0.495 | 0.118 | 0.195 | 0.091 | 0.438 |

PSRR (dB) | −44@100 Hz | N.A | −40@30 Hz | −50@DC | −40@100 Hz | N.A. | −70@100 Hz | N.A. |

Temperature range (°C) | 10–50 | −20–85 | 0–125 | −40–120 | −40–125 | N.A. | 0–120 | −25–85 |

TC (ppm/°C) | 45 | 40 | 165 | 42 | 63.6 | 134 | 265 | 22.1 |

Trimmed | NO | YES | NO | YES | YES | YES | NO | YES |

LR (mV/V) | 1.44 | 0.013 | 1.16 | 3.2 | 1.2 | 8 | 0.145 | 0.571 |

Area (mm^{2}) | 0.015 | 0.055 | 0.043 | 0.0522 | 0.012 | 0.013 | 0.0022 | 0.041 |

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**MDPI and ACS Style**

Ria, A.; Catania, A.; Bruschi, P.; Piotto, M.
A Low-Power CMOS Bandgap Voltage Reference for Supply Voltages Down to 0.5 V. *Electronics* **2021**, *10*, 1901.
https://doi.org/10.3390/electronics10161901

**AMA Style**

Ria A, Catania A, Bruschi P, Piotto M.
A Low-Power CMOS Bandgap Voltage Reference for Supply Voltages Down to 0.5 V. *Electronics*. 2021; 10(16):1901.
https://doi.org/10.3390/electronics10161901

**Chicago/Turabian Style**

Ria, Andrea, Alessandro Catania, Paolo Bruschi, and Massimo Piotto.
2021. "A Low-Power CMOS Bandgap Voltage Reference for Supply Voltages Down to 0.5 V" *Electronics* 10, no. 16: 1901.
https://doi.org/10.3390/electronics10161901