Invention Grant
US07683955B2 Photocurrent sensing circuit converting an illumination of visible light into an electric signal as well as photosensor and electronic device with the photocurrent sensing circuit 失效
光电流检测电路将可见光的照明转换成电信号,以及光电传感器和电子器件与光电流检测电路

  • Patent Title: Photocurrent sensing circuit converting an illumination of visible light into an electric signal as well as photosensor and electronic device with the photocurrent sensing circuit
  • Patent Title (中): 光电流检测电路将可见光的照明转换成电信号,以及光电传感器和电子器件与光电流检测电路
  • Application No.: US11907597
    Application Date: 2007-10-15
  • Publication No.: US07683955B2
    Publication Date: 2010-03-23
  • Inventor: Takayuki Shimizu
  • Applicant: Takayuki Shimizu
  • Applicant Address: JP Osaka
  • Assignee: Sharp Kabushiki Kaisha
  • Current Assignee: Sharp Kabushiki Kaisha
  • Current Assignee Address: JP Osaka
  • Agency: Birch, Stewart, Kolasch & Birch LLP
  • Priority: JP2006-303062 20061108
  • Main IPC: H04N3/14
  • IPC: H04N3/14
Photocurrent sensing circuit converting an illumination of visible light into an electric signal as well as photosensor and electronic device with the photocurrent sensing circuit
Abstract:
A photocurrent sensing circuit includes a logarithmic compression circuit; a cancellation circuit logarithmically compressing a current substantially equal in temperature coefficient of the photocurrent to convert the same into a voltage, and performing an addition or a subtraction on the converted voltage and a voltage converted from a photocurrent by logarithmically compression; a logarithmic operation circuit logarithmically compressing the voltage received from the cancellation circuit to produce a first voltage, logarithmically compressing a voltage proportional to a thermal voltage of the photocurrent to produce a second voltage, logarithmically compressing a current having thermal dependence of nearly zero to produce a third voltage and performing an addition or a subtraction of each of the second and third voltages with respect to the first voltage to produce a fourth voltage; and an inverse logarithmic transformation circuit performing inverse logarithmic transformation on the fourth voltage to output a current.
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