Burst mode digital optical receiver
First Claim
1. Apparatus for use in determining a logic value of a received optical signal which is converted to an electrical signal and amplified by a preamplifier, comprising:
- means for matching the DC level of said preamplifier;
means for automatically setting a logic level discriminating threshold; and
means responsive to said amplified electrically-converted signal, said matching DC level and said threshold for supplying an output indicative of the logic value of said received optical signal by using feedback from the output of said supplying means via said means for automatically setting a logic level;
wherein said preamplifier and said means for matching each have a transimpedance configuration and each has a Schottkey diode in it feedback path.
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Accused Products
Abstract
A DC coupled burst mode optical receiver circuit having improved sensitivity and improved dynamic range. The output of the receiver'"'"'s photodiode is single endedly amplified by a main preamplifier and the main preamplifier'"'"'s output is then converted, using an operational amplifier, e.g., with a gain of 1, to a differential signal which swings symmetrically around a threshold level. More specifically, the output of the main preamplifier is connected to one input of the operational amplifier. The output of a tracking preamplifier, which is identical to the main preamplifier, is coupled to the other input of the operational amplifier. The output of the tracking preamplifier is used to match the DC voltage of the main preamplifier, e.g., by being noise-free and by tracking changes in supply voltage, temperature, and the like. It is used to set the DC reference voltage for the standard operational amplifier functions. Between one output of the operational amplifier and the opposite sign input thereof is connected an automatic threshold controller (ATC). The ATC insures that the threshold level for determining the value of the logic value of the received signal is at the middle of the signal supplied from the main preamplifier. Preferably, the main preamplifier, the tracking preamplifier, the operational amplifier and the ATC are manufactured on a single integrated circuit. Optionally, a transimpedance resistor of both the main preamplifier and the tracking preamplifier are clamped to a predetermined maximum level, e.g., using a high-speed Schottkey diode, to enhance the dynamic range of the receiver.
18 Citations
15 Claims
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1. Apparatus for use in determining a logic value of a received optical signal which is converted to an electrical signal and amplified by a preamplifier, comprising:
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means for matching the DC level of said preamplifier; means for automatically setting a logic level discriminating threshold; and means responsive to said amplified electrically-converted signal, said matching DC level and said threshold for supplying an output indicative of the logic value of said received optical signal by using feedback from the output of said supplying means via said means for automatically setting a logic level; wherein said preamplifier and said means for matching each have a transimpedance configuration and each has a Schottkey diode in it feedback path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for use in determining a logic value of a received optical signal which is converted to an electrical signal and amplified by a main preamplifier, comprising:
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a tracking preamplifier which matches the DC level of said preamplifier; and an operational amplifier responsive to (i) said amplified electrically-converted signal, (ii) said matching DC level and (iii) an automatically set logic level discriminating threshold for supplying an output indicative of the logic value or said received optical a signal; wherein said threshold is developed using feedback from an output of said operational amplifier to an input of said operational amplifier via an automatic gain controller and wherein said tracking preamplifier has a transimpedance configuration and a Schottkey diode in its feedback path and said main preamplifier has a transimpedance configuration and a Schottkey diode in its feedback path. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification