Coded data generation or conversion – Analog to or from digital conversion – Differential encoder and/or decoder
Reexamination Certificate
2003-06-11
2004-08-31
Young, Brian (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Differential encoder and/or decoder
C341S144000, C375S289000, C375S300000, C375S302000
Reexamination Certificate
active
06784817
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data generator and a data generating method which utilize a quadrature signal composed of an I signal and a Q signal, and a transmitter utilizing this data generator.
2. Related. Art of the Invention
FIG. 25
shows an example of a conventional transmitter (for example, see Japanese Patent Laid-Open No. 2002-325109. The entire disclosure of the document are incorporated herein by reference in its entirety.). In
FIG. 25
, two output terminals of a data generator
5001
output I data (I signal) and Q data (Q signal) which are orthogonal to each other. These data are inputted to a modulator
5002
for modulation. A signal outputted from the modulator
5002
is amplified by an amplifier
5006
. The amplified signal is then radiated from an antenna
5007
.
However, in the transmitter shown in
FIG. 25
, the envelope of the signal outputted from the antenna
5007
varies markedly. The amplifier
5006
must be linear in order to prevent such a signal from being degraded in the transmitter. Ensuring the linearity of the amplifier
5006
causes the amplifier
5006
to consume more power.
In view of these problems, it is an object of the present invention to provide a data generator and a data generating method which serve to implement an efficient transmitter, and a transmitter utilizing this data generator.
SUMMARY OF THE INVENTION
The 1
st
aspect of the present invention is a data generating method comprising:
receiving an input signal to generate, from said signal, a quadrature signal composed of an I signal and a Q signal;
converting an amplitude component of said quadrature signal into a signal of a resolution lower than a resolution of said amplitude component;
dividing said I signal by the amplitude component of said quadrature signal to obtain normalized I data, multiplying said normalized I data by said converted signal to obtain first data, and outputting the first data; and
dividing said Q signal by the amplitude component of said quadrature signal to obtain normalized Q data, multiplying said normalized Q data by said converted signal to obtain second data, and outputting the second data.
The 2
nd
aspect of the present invention is a data generator comprising:
raw data generating means of generating, from an inputted signal, an I signal and a Q signal which are orthogonal to each other as well as an amplitude component of a quadrature signal composed of said I signal and said Q signal;
converting means of converting said amplitude component into a signal of a resolution lower than a resolution of said amplitude component;
first multiplying means of multiplying normalized I data obtained by dividing said I signal by the amplitude component, by said converted signal to obtain first data, and outputting the first data; and
second multiplying means of multiplying normalized Q data obtained by dividing said Q signal by the amplitude component, by said converted signal to obtain second data, and outputting the second data.
The 3
rd
aspect of the present invention is the data generator according to the 2
nd
aspect, wherein said converting means is delta sigma modulating means.
The 4
th
aspect of the present invention is the data generator according to the 3
rd
aspect, wherein said raw data generating means outputs said I signal, said Q signal, and said amplitude component,
wherein first dividing means connected to an output of said raw data generating means which outputs said amplitude component is connected to an output of said raw data generating means which outputs said I signal, and said first dividing means outputs said normalized I data by dividing said I signal by said amplitude component,
wherein second dividing means connected to the output of said raw data generating means which outputs said amplitude component is connected to an output of said raw data generating means which outputs said Q signal, and said second dividing means outputs said normalized Q data by dividing said Q signal by said amplitude component,
wherein said delta sigma modulating means is connected to the output of said raw data generating means which outputs the amplitude component,
wherein said delta sigma modulating means outputs a signal obtained by delta-sigma-modulating said amplitude signal,
wherein first multiplying means connected to an output of said delta sigma modulating means is connected to an output of said first dividing means, and said first multiplying means multiplies said normalized I data by the signal obtained by delta-sigma-modulating said amplitude signal, to obtain first data, and outputs the first data, and
wherein second multiplying means connected to the output of said delta sigma modulating means is connected to an output of said second dividing means, and said second multiplying means multiplies said normalized Q data by the signal obtained by delta-sigma-modulating said amplitude signal, to obtain second data, and outputs the second data.
The 5
th
aspect of the present invention is the data generator according to the 2
nd
aspect, wherein said raw data generating means outputs the normalized I data obtained by dividing said I signal by the amplitude component of said quadrature signal, the normalized Q data obtained by dividing said Q signal by the amplitude component of said quadrature signal, and the amplitude component of said quadrature signal.
The 6
th
aspect of the present invention is the data generator according to the 5
th
aspect, wherein said converting means is delta sigma modulating means.
The 7
th
aspect of the data generator according to the 2
nd
or 5
th
aspect, further comprising a fourth D/A converter and a fifth D/A converter which subject the first data and second data, respectively, outputted by said data generator, to D/A conversion.
The 8
th
aspect of the present invention is the data generator according to the 6
th
aspect, further comprising:
a first D/A converter connected to the output of said raw data generating means which outputs the normalized I data, of converting said normalized I data into analog data;
a second D/A converter connected to the output of said raw data generating means which outputs the normalized Q data, of converting said normalized Q data into analog data;
upsampling means connected to the output of said raw data generating means of upsampling the amplitude component of said quadrature signal; and
a third D/A converter connected to the output of said delta sigma modulating means, of converting said delta-sigma-modulated signal, into analog signal, and
wherein said delta sigma modulating means delta-sigma-modulates said upsampled signal,
wherein said first multiplying means is connected to an output of said first D/A converter and an output of said third D/A converter to multiply said normalized I data converted into analog data by said delta-sigma-modulated signal converted into analog signal and then to output a result of the multiplication,
wherein said second multiplying means is connected to an output of said second D/A converter and an output of said third D/A converter to multiply said normalized Q data converted into analog data by said delta-sigma-modulated signal converted into analog signal and then to output a result of the multiplication, and
wherein said first D/A converter and said second D/A converter have a higher vertical resolution than said third D/A converter, and said third D/A converter operates at a higher speed than said first D/A converter and said second D/A converter.
The 9
th
aspect of the present invention is the data generator according to the 2
nd
aspect, further comprising first delay means of delaying said I signal and second delay means of delaying said Q signal.
The 10
th
aspect of the present invention is the data generator according to the 2
nd
aspect, further comprising third delay means of delaying said normalized I signal and fourth delay means of delaying-said normalized Q signal.
The 11
th
aspect of the present invention is the data generator according to the 3
rd
or 6
th
asp
Adachi Hisashi
Matsuura Toru
Nguyen John B
Smith , Gambrell & Russell, LLP
Young Brian
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