continuous time linear equalizer - yonsei...
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![Page 1: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/1.jpg)
Continuous Time Linear Equalizer
2011321196 권대현
![Page 2: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/2.jpg)
Paper preview
• Title of the paper A 0.18-um CMOS 3.5-Gb/s Continuous-Time Adaptive Cable Equalizer Using
Enhanced Low-Frequency Gain Control Method
• Author Jong-Sang Choi, Moon-Sang Hwang, Deog-Kyoon Jeong
• Publication Journal IEEE Journal of Solid-State Circuits
![Page 3: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/3.jpg)
Contents
• Continuous Time Linear Equalizer (CTLE) Conventional CTLE Split path CTLE
• High frequency boosting control• Stable gain in unity gain path
• Modified CTLE Low frequency gain control Merged equalizer filter
• Conclusion
![Page 4: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/4.jpg)
Continuous Time Linear Equalizer
Reference clock
Recovered clock
Recovered data
Equalizer
Without EQ. at X
With EQ. at X
Channel response
Equalizer
ChannelOverall
fd
B
• Disadvantages Wideband frequency gain control inadequate Low frequency gain High frequency gain
X
![Page 5: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/5.jpg)
Continuous Time Linear Equalizer
• Split Path Amplifier
The characteristics of channel Low frequency pass well! High frequency cut Inter-Symbol Interference
Dividing the signal path into two : Low frequency signal path + High frequency signal path
High frequency gain boosting control!!
Unity gain path
High frequency boosting gain path
Attentions• Unity gain path Gain stable for PVT
• High frequency boosting Adaptive loop
![Page 6: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/6.jpg)
High Frequency Boosting Adaptive Loop
• Adaptive method for high frequency boosting gain Power comparing :
• High frequency boosting vs. Regulating Comparator
Using high pass filter & rectifier, power can be detected.
Difference between these two factor, boosting gain can be controlled
![Page 7: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/7.jpg)
Regulating Comparator
Regulating comparator Limiting amp.
High gain & Large BW not high frequency boosting Making signal saturation (Logic level: 1,0)
Regulating comparator output cannot be same with equalized output
Equalizing High frequency boosting
By comparing power , adequate boosting gain !!
Volta
geVo
ltage
Volta
geVo
ltage
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Stable Unity Gain Path
• Stable unity gain path Negative resistive feedback
Phase mismatch Input signal distortion
Feedback resistor ↑ Effective feedback , RC delay ↑ Input distortion
![Page 9: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/9.jpg)
Modified CTLE
• The points of the thesis High speed amplifier Stable fixed gain low frequency
• Modifying conventional CTLE Equalizing filter Low frequency gain control
![Page 10: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/10.jpg)
Modified CTLE
• Low frequency gain control
Power of output, equalizer filter vs. Power of output, regulating comparator Stable in unity gain path Still fast operation
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Modified CTLE
• Equalizing filter
Conventional filter Split topology , unity gain path & High frequency boosting path
Modified filter Merged-path topology• Need not summation circuit• Need not delay matching
![Page 12: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/12.jpg)
Jitter performance
Cablelength
Input signal
Amplitude
ResultsEye-diagram
BeforeEqualizing
AfterEqualizing
![Page 13: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/13.jpg)
Conclusion
• High-speed equalizer filter is designed
• Joint adaptation method Power comparing
High frequency loss & low-frequency gain variation Compensated!!
• Merged equalizing filter is used
• 3.5Gb/s @ 15-m RG-58 coaxial cable
![Page 14: Continuous Time Linear Equalizer - Yonsei Universitytera.yonsei.ac.kr/class/2013_1_2/lecture/Sp1_CTLE_KDH.pdf · Enhanced Low-Frequency Gain Control Method ... Continuous Time Linear](https://reader034.vdocuments.site/reader034/viewer/2022052406/5a75cfa67f8b9a1b688cbb7a/html5/thumbnails/14.jpg)