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US 6,208,204 B1Granted
Feedforward amplifier
AssigneeNTT Mobile Communications Network, Inc.
InventorsYasunori Suzuki, Toshio Nojima, Shoichi Narahashi
Life of this patent
Estimating the term…
Abstract
In the balance adjustment using a pilot signal in a distortion detector and a distortion canceller of a feed-forward amplifier for amplifying a CDMA transmission signal, a pilot code is spread by a long code different from that of the CDMA transmission signal to obtain the pilot signal. The pilot signal is converted to a signal of the transmission frequency band, and the converted signal is injected into the transmission signal at the input side of the amplifier. The pilot signal frequency band is detected from the output of an auxiliary amplifier of the distortion canceller and converted to the base band, thereafter being despread to detect the pilot signal (code).
Claims17
A feed-forward amplifier for amplifying a code division multiple access signal, comprising:
- a distortion detector which includes a main amplifier for amplifying a signal fed thereto from an input path and detects a nonlinear distortion component of said main amplifier;
- a distortion canceller which includes an auxiliary amplifier for amplifying the distortion component detected by said distortion detector and injects said amplified distortion component again into the output of said main amplifier, thereby canceling said distortion component;
- first pilot signal generating means for generating a first pilot signal;
- second pilot signal generating means for generating a second pilot signal;
- multiplexing means provided in said input path, for multiplexing said first pilot signal onto an input transmission signal and for providing the multiplexed signal to said distortion detector;
- first variable attenuating means and first phase shifting means inserted in said distortion detector;
- second pilot injecting means provided in the path of said main amplifier of said distortion detector, for injecting said second pilot signal;
- second variable attenuating means and second variable phase shifting means inserted in said distortion canceller;
- first level detecting means inserted in the path of said auxiliary amplifier of said distortion cancellor, for detecting the level of said first pilot signal;
- second level detecting means inserted in the output path of said distortion canceller, for detecting the level of said second pilot signal;
- and
- control means for controlling said first variable attenuating means and said first variable phase shifting means in a manner to minimize the detection level of said first level detecting means, and for controlling said second variable attenuating means and said second phase shifting means in a manner to minimize the detection level of said second level detecting means;
- wherein said first pilot signal generating means comprises:
- code generating means for generating a first pilot code of a predetermined code pattern;
- spreading means for spreading said first pilot code by a spreading code in a radio communication system of said code division multiple access;
- first signal converting means for converting the output of said spreading means to a signal of a predetermined frequency band to be amplified by said feed-forward amplifier, thereby generating said first pilot signal;
- and
- wherein said first level detecting means comprises:
- second signal converting means for frequency converting said predetermined frequency band amplified by said auxiliary amplifier to the base band;
- despreading means for spectrum-despreading the output of said second signal converting means by said spreading code;
- and
- code detecting means for detecting the level of said first pilot code from the output of said despreading means.
19 more elements
A feed-forward amplifier for amplifying a code division multiple access signal, comprising:
- a distortion detector which includes a main amplifier for amplifying a signal fed thereto from an input path and detects a nonlinear distortion component of said main amplifier;
- a distortion canceller which includes an auxiliary amplifier for amplifying the distortion component detected by said distortion detector and injects said amplified distortion component again into the output of said main amplifier, thereby canceling said distortion component;
- first pilot signal generating means for generating a multiplexed signal of a transmission signal and a first pilot signal, and for applying said multiplexed signal to said distortion detector via said input path;
- second pilot signal generating means for generating a second pilot signal;
- first variable attenuating means and first variable phase shifting means inserted in said distortion detector;
- pilot injecting means provided in the path of said main amplifier of said distortion detector, for injecting said second pilot signal;
- second variable attenuating means and second variable phase shifting means inserted in said distortion canceller;
- first level detecting means inserted in the path of said auxiliary amplifier of said distortion cancellor, for detecting the level of said first pilot signal;
- second level detecting means inserted in the output path of said distortion canceller, for detecting the level of said second pilot signal;
- and
- control means for controlling said first variable attenuating means and said first variable phase shifting means in a manner to minimize the detection level of said first level detecting means, and for controlling said second variable attenuating means and said second phase shifting means in a manner to minimize the detection level of said second level detecting means;
- wherein said first pilot signal generating means comprises:
- code generating means for generating a first pilot code of a predetermined code pattern;
- spreading means for spreading said first pilot code by a spreading code in a radio communication system of said code division multiple access to generate a base-band first pilot signal;
- multiplexing means for multiplexing said base-band first pilot signal from said spreading means onto a base-band transmission signal;
- and
- first signal converting means for converting the output of said multiplexing means to a signal of a predetermined frequency band to be amplified by said feed-forward amplifier, thereby generating said first pilot signal multiplexed onto said transmission signal;
- and
- wherein said first level detecting means comprises:
- second signal converting means for converting a signal of said predetermined frequency band amplified by said auxiliary amplifier to a base band signal;
- despreading means for spectrum-despreading the output of said second signal converting means by said spreading code;
- and
- code detecting means for detecting the level of said first pilot code from the output of said despreading means.
20 more elements
Dependencies are inferred from the claim text.