CATV optical receiving module
An optical receiving module, cable television technology, applied in electromagnetic receivers, optical fiber radios, TV systems adapted to optical transmission, etc., to achieve the effect of improving performance and unique principles
Inactive Publication Date: 2013-07-31
万军
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Problems solved by technology
[0003] Aiming at the disadvantages of the above-mentioned optical receivers in the prior art, such as low sensitivity when the input optical power is weak, and poor linearity when the input optical power is strong, this The invention provides a new cable TV optical receiving module for optical receivers, which adopts the photocurrent load resistance of the preamplifier, which can change its size with the intensity of the input optical power, and change with the decrease of the input optical power. Automatically increase, and automatically decrease with the increase of input optical power, thereby changing the thermal noise carrier-to-noise ratio of the preamplifier, so that the thermal noise carrier-to-noise ratio decreases by less than 2dB with the input optical power decreasing by 1dB
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[0015] This embodiment is one of the preferred embodiments of the present invention, and all other principles and basic structures that are the same as or similar to those of the present embodiment fall within the protection scope of the present invention.
[0016] Please refer to the attached figure 1 , Attached figure 1 This is the principle diagram of the equivalent circuit where the inventive point of the present invention lies. The photodiode is used as a photoelectric conversion unit and is connected to the signal input end of the amplifier. A feedback resistance unit R is connected across the signal output end and the signal input end of the amplifier. f , Feedback resistance unit R f Using an automatic variable resistor, the resistance of the feedback resistor unit Rf decreases with the increase of the input optical power, and increases with the decrease of the input optical power. In this embodiment, in order to explain the problem more simply and clearly, the DC bias ci...
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A CATV optical receiving module with wide dynamic range, high linearity and high sensitivity is disclosed. Said optical receiving module is used in the optical receiver of the terminal of CATV optical transmission system. Said optical receiving module comprises a photoelectric conversion unit and a preamplifier unit. The signal of said photoelectric conversion unit is output to said preamplifier unit. Said preamplifier unit is a trans-impedance amplifier, and feedback resistance unit is connected to the input and output end of the amplifier. In said optical receiving module, the feedback resistance unit has the function of voltage negative feedback, and is also the load resistance unit of photocurrent. The impedance of said feedback resistance unit is automatically increased when the input optical power is decreased, is automatically decreased when the input optical power is increased, and has certain dynamic range.
Description
technical field [0001] The invention discloses a light receiving module, in particular a large dynamic, high linearity and high sensitivity CATV light receiving module used in cable TV optical fiber transmission equipment and in the optical receiver of the cable TV signal fiber transmission system terminal. Background technique [0002] CATV optical receiver is one of the important components in fiber optic network (ie HFC) and upcoming fiber to the home (ie FTTH) applications. However, the existing optical receiver has problems such as low sensitivity when the input optical power is weak, and poor linearity when the input optical power is strong. Driven by market demand, the research on improving the performance of optical receivers has not stopped. The sensitivity of an optical fiber communication system is measured by the carrier-to-noise ratio of an optical link. The carrier-to-noise ratio of an optical link is mainly composed of three parts: one is the relative inten...
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IPC IPC(8): H04B10/60H04N7/22H04B10/2575
CPCH04B10/25751H03F3/08
Inventor 万军
Owner 万军