A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique
Herein, we present a low-power cyclic Vernier two-step time-to-digital converter (TDC) that achieves a wide input range with good linearity. Since traditional approaches require a large area or high power to achieve an input range >300 ns, we solve this problem by proposing a simple yet effic...
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| Format: | Article |
| Language: | English |
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MDPI AG
2018-11-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/18/11/3948 |
| _version_ | 1811302207890391040 |
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| author | Van Nhan Nguyen Duc Nha Duong Yunmo Chung Jong-Wook Lee |
| author_facet | Van Nhan Nguyen Duc Nha Duong Yunmo Chung Jong-Wook Lee |
| author_sort | Van Nhan Nguyen |
| collection | DOAJ |
| description | Herein, we present a low-power cyclic Vernier two-step time-to-digital converter (TDC) that achieves a wide input range with good linearity. Since traditional approaches require a large area or high power to achieve an input range >300 ns, we solve this problem by proposing a simple yet efficient TDC suitable for time-of-flight (TOF) sensors. In previous studies using the cyclic structure, the effect of startup time on the linearity of the TDC is not described. Thus, the achievable linearity has been limited when the TDC is used for applications requiring a high input range. We solve this problem by using a simple yet effective technique to compensate. The proposed technique is realized using (1) digitally-controlled oscillators (DCOs) that have dual frequency control and matched startup time; (2) an alignment detector that performs startup time correction by proper timing control; and (3) a fully symmetric arbiter that precisely detects the instant of edge alignment. To achieve a fine resolution for the cyclic Vernier TDC, we design two closely-matched DCOs with dual frequency control. The alignment detector performs the critical task of cancelling startup time via timing control. The detector is delay-compensated by using a dummy to provide matched loading for the two DCOs. To enhance the detection speed under low power, a current-reuse approach is employed for the arbiter. The TDC is fabricated using a 0.18 μm complementary metal⁻oxide⁻semiconductor (CMOS) process in a compact chip area of 0.028 mm<sup>2</sup>. Measured results show a dynamic range of 355 ns and a resolution of 377 ps. When the result is applied for TOF sensing, it corresponds to a distance range of 53.2 m and a resolution of 5.65 cm. Over a relatively large input range, good linearity is achieved, which is indicated by a DNL of 0.28 LSB<sub>rms</sub> and an INL of 0.96 LSB<sub>rms</sub>. The result corresponds to root mean square (RMS) error distance of 5.42 cm. The result is achieved by consuming a relatively low power of 0.65 mW. |
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| language | English |
| last_indexed | 2024-04-13T07:23:56Z |
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| spelling | doaj.art-b2524f893eed4c72b14a5b338767ca552022-12-22T02:56:33ZengMDPI AGSensors1424-82202018-11-011811394810.3390/s18113948s18113948A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction TechniqueVan Nhan Nguyen0Duc Nha Duong1Yunmo Chung2Jong-Wook Lee3School of Electronics and Information, Information and Communication System-on-chip (SoC) Research Center, Kyung Hee University, Yongin 17104, KoreaSchool of Electronics and Information, Information and Communication System-on-chip (SoC) Research Center, Kyung Hee University, Yongin 17104, KoreaSchool of Electronics and Information, Information and Communication System-on-chip (SoC) Research Center, Kyung Hee University, Yongin 17104, KoreaSchool of Electronics and Information, Information and Communication System-on-chip (SoC) Research Center, Kyung Hee University, Yongin 17104, KoreaHerein, we present a low-power cyclic Vernier two-step time-to-digital converter (TDC) that achieves a wide input range with good linearity. Since traditional approaches require a large area or high power to achieve an input range >300 ns, we solve this problem by proposing a simple yet efficient TDC suitable for time-of-flight (TOF) sensors. In previous studies using the cyclic structure, the effect of startup time on the linearity of the TDC is not described. Thus, the achievable linearity has been limited when the TDC is used for applications requiring a high input range. We solve this problem by using a simple yet effective technique to compensate. The proposed technique is realized using (1) digitally-controlled oscillators (DCOs) that have dual frequency control and matched startup time; (2) an alignment detector that performs startup time correction by proper timing control; and (3) a fully symmetric arbiter that precisely detects the instant of edge alignment. To achieve a fine resolution for the cyclic Vernier TDC, we design two closely-matched DCOs with dual frequency control. The alignment detector performs the critical task of cancelling startup time via timing control. The detector is delay-compensated by using a dummy to provide matched loading for the two DCOs. To enhance the detection speed under low power, a current-reuse approach is employed for the arbiter. The TDC is fabricated using a 0.18 μm complementary metal⁻oxide⁻semiconductor (CMOS) process in a compact chip area of 0.028 mm<sup>2</sup>. Measured results show a dynamic range of 355 ns and a resolution of 377 ps. When the result is applied for TOF sensing, it corresponds to a distance range of 53.2 m and a resolution of 5.65 cm. Over a relatively large input range, good linearity is achieved, which is indicated by a DNL of 0.28 LSB<sub>rms</sub> and an INL of 0.96 LSB<sub>rms</sub>. The result corresponds to root mean square (RMS) error distance of 5.42 cm. The result is achieved by consuming a relatively low power of 0.65 mW.https://www.mdpi.com/1424-8220/18/11/3948time-to-digital convertertime-of-flightinput rangestartup timecyclicVernierdigitally controlled oscillator |
| spellingShingle | Van Nhan Nguyen Duc Nha Duong Yunmo Chung Jong-Wook Lee A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique Sensors time-to-digital converter time-of-flight input range startup time cyclic Vernier digitally controlled oscillator |
| title | A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique |
| title_full | A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique |
| title_fullStr | A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique |
| title_full_unstemmed | A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique |
| title_short | A Cyclic Vernier Two-Step TDC for High Input Range Time-of-Flight Sensor Using Startup Time Correction Technique |
| title_sort | cyclic vernier two step tdc for high input range time of flight sensor using startup time correction technique |
| topic | time-to-digital converter time-of-flight input range startup time cyclic Vernier digitally controlled oscillator |
| url | https://www.mdpi.com/1424-8220/18/11/3948 |
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