A 0.4-to-1 V Voltage Scalable $\Delta \Sigma $ ADC With Two-Step Hybrid Integrator for IoT Sensor Applications in 65-nm LP CMOS

This brief presents a two-step hybrid integrator (TSHI) that can operate at a wide supply voltage range, which is demonstrated with a third-order <inline-formula> <tex-math notation="LaTeX">${\Delta \Sigma }$ </tex-math></inline-formula> analog-to-digital converter (ADC). The proposed TSHI consists of a zero-crossing-detector (ZCD)-based integrator and an inverter-based integrator. In the coarse-integration step, the ZCD-based integrator performs a fast integration without concern for overshoot or detection delay issues. In the fine-integration step, the inverter-based integrator performs the residual integration with high accuracy. Hence, the TSHI provides fast and accurate integration process. In addition, the TSHI supports trade-off between voltage-scalable bandwidth and power consumption for an energy efficient operation of Internet-of-Things sensor nodes, owing to the scalable operation of the ZCD and inverter. The proposed <inline-formula> <tex-math notation="LaTeX">${\Delta \Sigma }$ </tex-math></inline-formula> ADC is fabricated in a 65-nm LP CMOS process, and the active area is 0.38 mm<sup>2</sup>. The fabricated ADC operates at supply voltages from 0.4 to 1 V. Depending on the supply voltage and sampling frequency, the power consumption and bandwidth of the ADC can be scaled from 12.7 to <inline-formula> <tex-math notation="LaTeX">$948~{\mu }{\mathrm{W}}$ </tex-math></inline-formula> and from 7.5 to 400 kHz, respectively. The ADC maintains an SNDR higher than 60 dB within the operating supply range.

[1]  Franco Maloberti,et al.  Active-Passive ΔΣ Modulator for High-Resolution and Low-Power Applications , 2017, IEEE Trans. Very Large Scale Integr. Syst..

[2]  Un-Ku Moon,et al.  A 630μW zero-crossing-based ΔΣ ADC using switched-resistor current sources in 45nm CMOS , 2009, 2009 IEEE Custom Integrated Circuits Conference.

[3]  Jeongjin Roh,et al.  A True 0.4-V Delta–Sigma Modulator Using a Mixed DDA Integrator Without Clock Boosted Switches , 2014, IEEE Transactions on Circuits and Systems II: Express Briefs.

[4]  Youngcheol Chae,et al.  Low Voltage, Low Power, Inverter-Based Switched-Capacitor Delta-Sigma Modulator , 2009, IEEE J. Solid State Circuits.

[5]  W. Dargie,et al.  Dynamic Power Management in Wireless Sensor Networks: State-of-the-Art , 2012, IEEE Sensors Journal.

[6]  Atila Alvandpour,et al.  Low-Power DT $\Delta \Sigma$ Modulators Using SC Passive Filters in 65 nm CMOS , 2014, IEEE Transactions on Circuits and Systems I: Regular Papers.

[7]  Un-Ku Moon,et al.  Pseudo-differential zero-crossing-based circuit with differential error suppression , 2010, Proceedings of 2010 IEEE International Symposium on Circuits and Systems.

[8]  Franco Maloberti,et al.  Active–Passive $\Delta \Sigma $ Modulator for High-Resolution and Low-Power Applications , 2017, IEEE Transactions on Very Large Scale Integration (VLSI) Systems.

[9]  Michiel Steyaert,et al.  A 250 mV 7.5 μW 61 dB SNDR SC ΔΣ Modulator Using Near-Threshold-Voltage-Biased Inverter Amplifiers in 130 nm CMOS , 2012, IEEE Journal of Solid-State Circuits.

[10]  Gunhee Han,et al.  Low Voltage, Low Power, Inverter-Based , 2009 .

[11]  Atila Alvandpour,et al.  Low-Power DT ΔΣ Modulators Using SC Passive Filters in 65 nm CMOS. , 2014 .

[12]  Chao Chen,et al.  A 1V 14b self-timed zero-crossing-based incremental ΔΣ ADC , 2013, 2013 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[13]  Anantha Chandrakasan,et al.  A Resolution-Reconfigurable 5-to-10-Bit 0.4-to-1 V Power Scalable SAR ADC for Sensor Applications , 2013, IEEE Journal of Solid-State Circuits.

[14]  Jeongjin Roh,et al.  A 0.4 V 63 $\mu$W 76.1 dB SNDR 20 kHz Bandwidth Delta-Sigma Modulator Using a Hybrid Switching Integrator , 2015, IEEE Journal of Solid-State Circuits.

[15]  Yan Han,et al.  A 0.8-V 230-$\mu$ W 98-dB DR Inverter-Based $\Sigma \Delta$ Modulator for Audio Applications , 2013, IEEE Journal of Solid-State Circuits.