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Ultrawide-bandwidth low-noise optical receiver

  • US 5,010,588 A
  • Filed: 03/06/1989
  • Issued: 04/23/1991
  • Est. Priority Date: 03/10/1988
  • Status: Expired due to Term
First Claim
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1. An optical receiver having a bandwidth that extends from near dc to the multi-gigahertz range for converting a received optical signal to an amplified electrical signal at the output of the receiver, said receiver comprising:

  • photodetector means for converting the received optical signal to a proportional low-level electrical signal,inductive/resistive frequency enhancement means connected to said photodetector means for extending the high frequency response of a first stage of an amplifying means and for providing a high input impedance to said first stage,said amplifying means being connected between said frequency enhancement means and said receiver output and comprising a plurality of amplifying stages each comprising a transistor amplifier and a microwave matching circuit comprising a modified T-network having as series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor, said amplifying stages providing individual input and output impedances decreasing successively from said high input impedance at said first of said stages to a low output impedance at the last of said stages, the resistor in the shunt-leg of each modified T-network being chosen to extend the bandwidth of each stage to near the dc level and the values of said inductive and microwave elements being chosen to preserve the high frequency response as extended by said frequency enhancement means.

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