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 Title: |
US5077532:
Feed forward distortion minimization circuit
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Obermann, Mark G.; Niles, IL
Long, James F.; Glen Ellyn, IL
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| Assignee: |
Motorola, Inc., Schaumburg, IL
other patents from MOTOROLA, INC. (386735) (approx. 18,357)
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| Published / Filed: |
1991-12-31
/ 1990-12-17
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| Application Number: |
US1990000628539
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| IPC Code: |
Advanced:
H03F 1/32;
Core:
more...
IPC-7:
H03F 1/32;
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| U.S. Class: |
Current:
330/151;
327/100;
330/149;
Original:
330/151;
330/149;
328/163;
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| Field of Search: |
330/151,149,52
328/163
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| Priority Number: |
| 1990-12-17 |
US1990000628539 |
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| Abstract: |
A feed forward distortion minimization circuit which receives an input signal and routes the input signal along two signal paths is disclosed. One path, the main signal path, includes a distortion generator such as, for example, a power amplifier, which generates an output signal having a distortion component. The other path, the feed forward signal path, includes a delay line responsive to the input signal for feeding the input signal forward, without distortion. The output signal from the distortion generator is combined with a fed forward input signal to form an error signal representative of the distortion component. A feedback circuit is employed to detect a DC current or RF voltage proportional to the error signal's signal strength and to adjust the amplitude and the phase of signals in the feed forward or main signal paths to reduce the carrier to distortion ratio of the error signal. Thereafter, the error signal is subtracted from the main signal path to cancel any distortion components therein. The subtraction is controlled by circuitry which detects distortion at the main signal path output, and adjusts the amplitude and the phase of the error signal, so that when the error signal is subtracted from the main signal path, substantially all distortion is cancelled.
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| Attorney, Agent or Firm: |
Hillman, Val Jean F. ;
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| Primary / Asst. Examiners: |
LaRoche, Eugene R.; Dinh, Tan
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| INPADOC Legal Status: |
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| Family: |
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First Claim:
Show all 11 claims |
What is claimed is:
1. A feed forward distortion minimization circuit comprising:
- means, for receiving an input signal;
- a main signal path having an input connected to the receiving means and a distortion generating means responsive to the input signal for generating an output signal having a distortion component;
- a feed forward signal path having an input connected to the receiving means for feeding the input signal forward, without distortion;
- means, for combining the distortion generating means output signal with a fed forward input signal to form an error signal substantially representative of the distortion component;
- detecting means, operably coupled to the combining means, for detecting a DC current proportional to the entire carrier energy within the error signal; and
- feedback circuit means, responsive to the detected signal, for adjusting the amplitude and the phase of signals in at least one signal path, to reduce the carrier to distortion ratio of the error signal.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 51 U.S. patent(s) that reference this one
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