Patent EP0570979A1 successfully refreshed from Google Patents.
EP0570979A1
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EP
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Quadrature modulation circuit
Assignee: NEC Corp
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Filing: 1993-05-21
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Granted: —
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Expires: 2013-05-21
Abstract
Abstract A quadrature modulation circuit (300) of the present invention has a phase shifter (302) whose shifting amount is fixed at 90 degrees, a minute amount-phase shifter (303) whose shifting amount is variable, a detector (307) for detecting a RF signal supplied from the quadrature modulation circuit (300) by a direct voltage signal, and a control circuit (308) for generating a control signal in accordance with a direct voltage signal from the detector (307). The phase shifting amount of the minute amount-phase shifter (303) is adjusted by the control signal whereby a total amount of the phase shifting is maintained at 90 degrees.
Inventors
- 👤 Hideki Ueda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 13:56
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/36; H04L27/362; H04L27/364; H03; H03C; H03C3/00; H03C3/38; H03C3/40
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
141 words
A quadrature modulation circuit, comprising: means for supplying a local signal and two baseband signals; means for dividing said local signal into two local signals; means for shifting a phase of at least one of said two local signals to provide a relative phase difference of 90 degrees therebetween; a first mixer for combining said first baseband signal with a first one of said two local signals, whereby a first combined signal is obtained; a second mixer for combining said second baseband signal with a second one of said two local signals, whereby a second combined signal is obtained; means for adding said first and second combined signals; and means for controlling said shifting means in accordance with an output signal of said adding means, whereby said two local signals are adjusted to have a relative phase difference of 90 degrees.
Claim 2
Dependent Claim
41 words
A quadrature modulation circuit, according to claim 1, wherein: said shifting means comprises a first phase shifter whose shifting amount is fixed to be 90 degrees, and a variable phase shifter whose shifting amount can be adjusted by said control means.
Claim 3
Dependent Claim
79 words
A quadrature modulation circuit, according to claim 1 or 2, wherein: said shifting means includes first and second phase shifter for shifting phases of said first and second local signals by predetermined shifting amounts, respectively, and a third phase shifter for shifting at least one of said first and second local signals which have, been phase-shifted by said first and second phase shifter; said third phase shifter being able to be adjusted in shifting amount by said control means.
Claim 4
Dependent Claim
70 words
A quadrature modulation circuit, according to claim 1, 2, or 3, wherein: said controlling means comprises a band-pass filter for limiting a band of said output signal of said adding means, a detector for detecting a signal passing through said band-pass filter by a direct voltage signal, and a control circuit for controlling a shifting amount of said shifting means in accordance with said direct voltage signal from said detector.
Claim 5
Dependent Claim
92 words
A quadrature modulation circuit, according to any one of claims 1 to 4, wherein: said controlling means comprises a band-pass filter for limiting a band of said output signal of said adding means, a detector for detecting a signal passing through said band-pass filter by a direct voltage signal, and a control circuit for controlling a shifting amount of said shifting means in accordance with said direct voltage signal from said detector; said control circuit controlling a shifting amount of said shifting means to minimize said direct voltage signal from said detector.
References Cited (Backward Citations)
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