Measurement of RF current waveform of a source driver chip used in a liquid crystal-TV display panel

Shoichi Kobayashi, Hideki Torizuka, Sandeep Dhungana, Masahiro Yamaguchi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Instantaneous RF current waveform of the power line for a source driver chip used in a typical colour active matrix type liquid crystal-TV display panel has been evaluated for the first time based on magnetic near field measurement. A 16-inch panel set was opened to bare the 10 parallelly-connected source driver chips. Each chip is with 2.7 mm x 12.0 mm in size, and drives 207 liquid crystal cells with nominally 100 pF for each at 16 Vmax with common voltage level of 8 V, which corresponds to the maximum charge of 0.17 μC. A shielded-loop probe (CP-2S, window size: 0.2 mm x 1.0 mm) was used to measure the induced voltage waveform. The analogue power line was identified as the major source of RF magnetic field noise. Then RF current waveform was calculated based on the Faraday's low, using the size and geometry of measurement system. It is known the cells are fully charged when all the panel cells display "white." The measured corresponding peak current was 130 mA with rise time of less than 10 ns at the turned-off of clock pulse, followed by a triangular-like decrease for 1.7 μs. The corresponding electric charge was 0.14 μC, which is closely to the maximum possible charge of 0.17 μC. The spectrum of RF current has significant intensity even around 1 GHz.

Original languageEnglish
Title of host publicationIEEE International Symposium on Electromagnetic Compatibility, EMC 2010 - Final Program
Pages505-508
Number of pages4
DOIs
Publication statusPublished - 2010 Dec 1
Event2010 IEEE International Symposium on Electromagnetic Compatibility, EMC 2010 - Fort Lauderdale, FL, United States
Duration: 2010 Jul 252010 Jul 30

Publication series

NameIEEE International Symposium on Electromagnetic Compatibility
ISSN (Print)1077-4076

Other

Other2010 IEEE International Symposium on Electromagnetic Compatibility, EMC 2010
CountryUnited States
CityFort Lauderdale, FL
Period10/7/2510/7/30

Keywords

  • EMC
  • LCD panel
  • Magnetic near-field measurement Faraday's low
  • RF current waveform
  • Shielded loop probe

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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