A 20ch TDC/ADC hybrid SoC for 240×96-pixel 10%-reflection &lt;0.125%-precision 200m-range imaging LiDAR with smart accumulation technique

Yoshioka, Kentaro; Kubota, Hiroshi; Fukushima, Tadashi; Kondo, Satoshi; Ta, Tuan Thanh; Okuni, Hidenori; Watanabe, K.; Ojima, Yoshinari; Kimura, Kozo; Hosoda, Sohichiroh; Oota, Yutaka; Koizumi, Toru; Kawabe, Naoyuki; Ishii, Yusuke; Iwagami, Yoichiro; Yagi, Seitaro; Fujisawa, Isao; Kano, Nobuo; Sugimoto, Tomohiro; Kurose, Daisuke; Waki, Naoya; Higashi, Y.; Nakamura, Tetsuya; Nagashima, Yoshikazu; Ishii, Hirotomo; Sai, Akihide; Matsumoto, Nobu

doi:10.1109/isscc.2018.8310199

Cited by 11 publications

(3 citation statements)

References 1 publication

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“…In general, the overall chip area of a conventional SAR ADC is limited by the area of the CDAC, which consists of binaryweighted capacitors. Capacitors take up most of the area of a conventional SAR ADC, and thus the chip area is determined by the capacitance density [19,20]. The area of the CDAC is thus used to estimate the chip area of this work, even though our future efforts will incorporate the silicon implementation of this work.…”

Section: Areamentioning

confidence: 99%

A Tunable Foreground Self-Calibration Scheme for Split Successive-Approximation Register Analog-to-Digital Converter

Park,

Lee,

Abraham

et al. 2024

Electronics

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The capacitor mismatch among diverse defects caused by variations in the manufacturing process significantly affects the linearity of the capacitor array used to implement the capacitive digital-to-analog converter (CDAC) in the successive-approximation register (SAR) analog-to-digital converter (ADC). Accordingly, the linearity of the SAR ADC is limited by that of capacitor array, resulting in serious yield loss. This paper proposes an efficient foreground self-calibration technique to enhance the linearity of the SAR ADCs by mitigating the capacitor mismatch based on the split ADC architecture along with variable capacitors. In this work, two ADC channels (i.e., ADC1 and ADC2) for the split ADC architecture include their capacitive DACs (CDACs) whose binary-weighted capacitor arrays consist of variable capacitors. A charge-sharing SAR ADC is used for each ADC channel. In the normal operation mode, their digital outputs are averaged to be the final ADC output, as in a conventional split ADC. In the calibration mode, every single binary-weighted capacitor for the two ADCs is sequentially calibrated by making parallel or/and antiparallel connection among two or thee capacitors from the two channels. For instance, because the capacitors of the CDACs ideally exhibit the binary-weighted relation as Cn=2×Cn−1, the variable capacitor Cn of ADC1 can be updated to be closest to the sum of Cn−1 of ADC1 and Cn−1 of ADC2 for the calibration. For the process, the two capacitor arrays of the two ADCs can be reconfigured to be connected to each other, so that the Cn of ADC1 can be connected with two of the Cn−1 of ADC1 and ADC2 in antiparallel. The two voltages at the top and the bottom plates of the CDAC are compared by a comparator of ADC1, and the comparison results are used to update Cn. This process is iterated, until Cn is in agreement with the sum of two of Cn−1. Finally, all the capacitors can be calibrated in this way to have the binary-weighted relation. The simulation results based on the proposed work with a split SAR ADC model verified that the proposed technique can be practically used, by showing that the total harmonic distortion and the signal-to-noise-and-distortion ratio were enhanced by 21.8 dB and 6.4 dB, respectively.

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Section: Areamentioning

confidence: 99%

A Tunable Foreground Self-Calibration Scheme for Split Successive-Approximation Register Analog-to-Digital Converter

Park,

Lee,

Abraham

et al. 2024

Electronics

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“…However, the frequency modulated continuous wave (FMCW) method for LiDAR makes it possible to increase the optical output power, because it uses a 1550nm light length [8]. It also mitigates the difficulty of the range resolution improvement, because a lower sampling rate analog-to-digital converter can be used for the FMCW method unlike the full-waveform and the Time-of-Flight methods [9]. With these advantages, the FMCW method will be broadly applied to LiDAR systems in the future.…”

Section: Introductionmentioning

confidence: 99%

“…The method can take the measurements for P points with only one FFT calculation. This reduction saves the power to the FFT module as like Equation (9).…”

Section: Introductionmentioning

confidence: 99%

Multipoint Combined Processing for FMCW LiDAR

2022

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This paper proposes a multipoint processing method (MCP) for FMCW LiDAR. The proposed method reduces the number of fast Fourier transform (FFT) calculation compared to the traditional FMCW LiDAR method. This leads to a reduced power consumption. To end this, the proposed method accumulates the multiple beat frequencies in the time domain before the FMCW LiDAR extracts the measured distances from the beat frequencies using the fast Fourier transform (FFT). In order to distinguish the distances that are extracted from the FFT operation, a pulse-width modulation (PWM) counter and an analog comparator were applied. A hysteresis analog comparator was used to increase the immunity from the external noise. When the measured distances are too close to be indistinguishable by the FFT, it may fail to distinguish the measurement order. In order to respond to this situation, the proposed method includes a point-calibration algorithm. The root mean square error (RMSE) and hardware resource usage are utilized in order to assess the performance of the proposed method. The experimental results show that the proposed method achieves power usage time savings compared to the traditional method.

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Data selection and de-noising based on reliability for long-range and high-pixel resolution LiDAR

Tanabe

Kubota

Sai

et al. 2018

2018 IEEE Symposium in Low-Power and High-Speed Chips (COOL CHIPS)

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A 20ch TDC/ADC hybrid SoC for 240×96-pixel 10%-reflection <0.125%-precision 200m-range imaging LiDAR with smart accumulation technique

Cited by 11 publications

References 1 publication

A Tunable Foreground Self-Calibration Scheme for Split Successive-Approximation Register Analog-to-Digital Converter

A Tunable Foreground Self-Calibration Scheme for Split Successive-Approximation Register Analog-to-Digital Converter

Multipoint Combined Processing for FMCW LiDAR

Data selection and de-noising based on reliability for long-range and high-pixel resolution LiDAR

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