A Process-Independent and Highly Linear DCO for Crowded Heterogeneous IoT Devices in 65-nm CMOS

J. Gorji | M.B. Ghaznavi-Ghoushchi

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URL :   http://research.shahed.ac.ir/WSR/WebPages/Report/PaperView.aspx?PaperID=43851
Date :  2017/06/26
Publish in :    IEEE Transactions on Very Large Scale Integration (VLSI) Systems
DOI :  https://doi.org/10.1109/tvlsi.2017.2715167
Link :  https://doi.org/10.1109/TVLSI.2017.2715167
Keywords :DCO, Devices, CMOS

Abstract :

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The Internet of Things (IoT) devices are manufactured under different fabrication quality standards, considering the wide variety of vendors. As a result, global process variations in the IoT system-on-chip (SoC) are an enormous concern that can affect reliability of the device. Among the components in a typical SoC, oscillator is the most susceptible element to process variations. This paper proposes a feedback-assisted digitally controlled oscillator (DCO). The DCO has 512 operating modes, for wide-range frequency tuning from 0.6 to 3.1 GHz. By adding a dynamic feedback to inner current-controlled oscillator using a frequency-to-current converter, the DCO remains linear and invariant to the process for entire 2.5-GHz frequency band. Thanks to pseudodifferential cross-coupled structure used in each stage, this paper achieves a 2.3 ps deterministic jitter at 1.87-GHz output frequency. Furthermore, Monte Carlo analysis is performed at 1.87-GHz frequency; indicate that standard deviation from the mean is 2.47 that verifies reliability of this design. Power consumption varies from 0.86 to 3.68 mW at 1.2 V supply voltage, corresponding to the code word. The DCO is implemented in 65-nm standard CMOS process.