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US 6,587,243 B1Granted
Second order predistortor for a return laser transmitter
AssigneeGeneral Instrument Corporation
InventorShotung Zhou
Life of this patent
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Abstract
The invention provides a second order predistortion circuit which reduces distortions generated by an optical return laser transmitter. The predistortion circuit uses emitter follower as a second order distortion generator. Controlling the emitter D.C. current, the level of second order distortion signals can be easily controlled over a wide range. This predistortion circuit can be confirmed with a digital control circuit for laser distortion compensation over temperature.
Claims11
A method of reducing distortion levels in an optical return transmitter comprising:
- receiving an electrical input signal into an input stage;
- introducing a second order distortion signal to the electrical signal by use of an emitter follower stage;
- and,
- controlling the D.C. current of the emitter follower amplifier to introduce a desired level of second order distortion.
1 more element
A predistortion circuit for a laser transmitter comprising:
- an input stage coupled to an electrical signal input;
- an emitter follower stage coupled to an output of the input stage;
- an amplifier stage coupled to an output of the emitter follower stage;
- and,
- a distortion controller coupled to a control input of the emitter follower stage whereby the distortion controller generates a signal to control the amount of second order distortion generated in the emitter follower stage.
2 more elements
Dependencies are inferred from the claim text.