A/D converter apparatus with frequency conversion function and radio apparatus using the same

An A/D converter apparatus comprising:

• a negative feedback loop having a main signal line supplied with an input signal of a predetermined frequency and a feedback signal line receiving a feedback signal;
• A/D conversion means including a frequency converter connected to said main signal line for frequency-converting the input signal to a frequency-converted signal having a frequency lower than that of the input signal and an A/D converter for A/D-converting the frequency-converted signal of said frequency converter;
• D/A conversion means connected in said feedback signal line and having a frequency conversion function for frequency-converting the feedback signal to a frequency-converted feedback signal having a frequency substantially equal to that of the input signal;
• and
• subtraction means for subtracting the frequency-converted feedback signal from said D/A conversion means from the input signal to supply a subtraction result signal to said A/D conversion means.

An A/D converter apparatus comprising:

• a negative feedback loop having a main signal line supplied with an input signal of a predetermined frequency and a feedback signal line receiving a feedback signal;
• A/D conversion means including a first frequency converter for frequency-converting the input signal to a frequency-converted signal having a frequency lower than that of the input signal and an A/D converter for A/D-converting the frequency-converted signal from said first frequency converter;
• D/A conversion means including a D/A converter connected to the feedback signal line for D/A-converting the feedback signal and a second frequency converter for frequency-converting an output signal from said D/A converter to a frequency-converted feedback signal having a frequency substantially equal to that of the input signal;
• and
• subtraction means for subtracting the frequency-converted feedback signal from said D/A conversions means from the input signal to supply a subtraction result signal to said A/D conversion means.

An A/D converter apparatus comprising:

• a negative feedback loop having a main signal line supplied with an input signal of a predetermined frequency and a feedback signal line receiving a feedback signal;
• A/D conversion means connected in said main signal line and having a first frequency conversion function for frequency-converting the input signal to a frequency-converted signal having a frequency different from that of the input signal;
• D/A conversion means connected in said feedback signal line and having a second frequency conversion function for frequency-converting the feedback signal to a frequency-converted feedback signal having a frequency substantially equal to that of the input signal;
• and
• subtraction means for subtracting the frequency-converted feedback signal from said D/A conversion means from the input signal to supply a subtraction result signal to said A/D conversion means, and
• wherein said A/D conversion means comprises a first reference signal generator for generating first orthogonal reference signals and a pair of A/D converters connected in said main signal line for A/D-converting the input signal in accordance with the first orthogonal reference signals to output a pair of A/D-converted signals corresponding to the frequency-converted signal, and wherein said D/A conversion means comprises a pair of D/A converters connected in said feedback signal line for D/A converting feedback signals corresponding to the A/D-converted signals, a second reference signal generator for generating second orthogonal reference signals, a pair of mixers for multiplying D/A converted signals from said D/A converters by the second orthogonal reference signals, respectively, to output quadrature-modulated signals, and an adder for adding the quadrature-modulated signals from said mixers together to output the frequency-converted feedback signal.

An A/D converter apparatus according to claim comprising:

• a negative feedback loop having a main signal line supplied with an input signal of a predetermined frequency and a feedback signal line receiving a feedback signal;
• A/D conversion means connected in said main signal line and having a first frequency conversion function for frequency-converting the input signal to a frequency-converted signal having a frequency different from that of the input signal;
• D/A conversion means connected in said feedback signal line and having a second frequency conversion function for frequency-converting the feedback signal to a frequency-converted feedback signal having a frequency substantially equal to that of the input signal;
• and
• subtraction means for subtracting the frequency-converted feedback signal from said D/A conversion means from the input signal to supply a subtraction result signal to said A/D conversion means, and
• wherein said A/D conversion means comprises a first reference signal generator for generating first orthogonal reference signals, a pair of mixers connected in said main signal line for multiplying the input signal by the first orthogonal reference signals to output quadrature-modulated signals, and a pair of A/D converters for A/D-converting the quadrature-modulated signals, and wherein said D/A conversion means comprises a second reference signal generator for generating second orthogonal reference signals, a pair of D/A converters connected in said feedback signal line for D/A-converting feedback signals corresponding to A/D-converted signals from said A/D converters in accordance with the second orthogonal reference signals to output quadrature A/D-converted signals, and an adder for adding the quadrature A/D-converted signals together to output the frequency-converted feedback signal.

An A/D converter apparatus comprising:

• a negative feedback loop having a main signal line supplied with an input signal of a predetermined frequency and a feedback signal line receiving a feedback signal;
• A/D conversion means connected in said main signal line and having a first frequency conversion function for frequency-converting the input signal to a frequency-converted signal having a frequency different from that of the input signal;
• D/A conversion means connected in said feedback signal line and having a second frequency conversion function for frequency-converting the feedback signal to a frequency-converted feedback signal having a frequency substantially equal to that of the input signal;
• and
• subtraction means for subtracting the frequency-converted feedback signal from said D/A conversion means from the input signal to supply a subtraction result signal to said A/D conversion means, and
• wherein said A/D conversion means comprises a first reference signal generator for generating first orthogonal reference signals and a pair of A/D converters connected in said main signal line for A/D-converting the input signal in accordance with the first orthogonal reference signals to output a pair of A/D converted signals corresponding to the frequency-converted signal, and wherein said D/A conversion means comprises a second reference signal generator for generating second orthogonal reference signals, a pair of D/A converters connected in said feedback signal line for D/A-converting feedback signals corresponding to A/D-converted signals from said A/D converters in accordance with the second orthogonal reference signals to output quadrature A/D-converted signals, and an adder for adding the quadrature A/D-converted signals together to output the frequency-converted feedback signal.