Delta Sigma Modulator and Delta Sigma Analog-Digital Converter

A ΔΣ modulator comprising:

• an oscillator for changing a frequency thereof according to an input signal;
• a reference signal source for outputting a reference signal at a predetermined frequency;
• a mixer for mixing the signals from the oscillator and the reference signal source;
• a low-pass filter for passing a low frequency component of a signal output from the mixer;
• means for quantizing a frequency modulation signal output from the low-pass filter;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the quantizing means,
• wherein a center oscillation frequency of the oscillator is set higher than a target center oscillation frequency of the frequency modulation signal.

A ΔΣ modulator comprising:

• a first oscillator for changing a frequency thereof according to the input signal;
• a second oscillator for changing a frequency thereof according to the input signal;
• a mixer for mixing the signals from the two oscillators;
• a low-pass filter for passing a low frequency component of a signal output from the mixer;
• means for quantizing a frequency modulation signal output from the low-pass filter;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the quantizing means,
• wherein either the first oscillator or the second oscillator has a positive frequency dependency to the input signal, and the other has a negative frequency dependency to the input signal, and center oscillation frequencies of the two oscillators are set higher than a target center oscillation frequency of the frequency modulation signal.

A ΔΣ modulator comprising:

• an integrator for integrating an analog input signal;
• an oscillator for changing a frequency thereof according to an output signal from the integrator;
• means for quantizing a frequency modulation signal output from the oscillator;
• an operation circuit for applying a first predetermined operation to a digital signal output from the quantizing means;
• means for detecting that the output signal from the integrator reaches a predetermined value;
• means for resetting the integrator based on a detection signal from the detecting means;
• and
• a processor for applying a second predetermined operation to a digital signal output from the operation circuit based on the detection signal output from the detecting means.

A ΔΣ modulator comprising:

• an integrator for integrating an analog input signal;
• a quantizer for quantizing an output signal from the integrator;
• an operation circuit for applying a first predetermined operation to a digital signal output from the quantizer;
• means for detecting that the output signal from the integrator reaches a predetermined value;
• means for resetting the integrator based on a detection signal from the detecting means;
• and
• a processor for applying a second predetermined operation to a digital signal output from the operation circuit based on the detection signal output from the detecting means.

A ΔΣ modulation device comprising:

• a first ΔΣ modulator comprising an integrator for integrating an analog input signal, a quantizer for quantizing an output signal from the integrator, and a first adder for inverting the polarity of an output signal from the quantizer and adding the inverted output signal to the analog input signal;
• a second adder for inverting the polarity of either the output signal from the quantizer of the first ΔΣ modulator or the output signal from the integrator of the first ΔΣ modulator, and adding the inverted signal to the other one of the signals;
• a second ΔΣ modulator for modulating a signal from the second adder;
• a differentiator for differentiating a digital signal from the second ΔΣ modulator;
• and
• a processor for applying a predetermined operation to a digital signal output from the differentiator and the digital signal output from the quantizer of the first ΔΣ modulator,
• wherein a sampling frequency of the second ΔΣ modulator is higher than a sampling frequency of the first ΔΣ modulator.

A ΔΣ modulation device comprising:

• a first ΔΣ modulator comprising an integrator for integrating an analog input signal, a quantizer for quantizing an output signal from the integrator;
• and an adder for inverting the polarity of an output signal from the quantizer and adding the inverted output signal to the analog input signal;
• a second ΔΣ modulator for modulating the signal output from the integrator of the first ΔΣ modulator;
• a differentiator for differentiating a digital signal from the second ΔΣ modulator;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the differentiator and the digital signal output from the first ΔΣ modulator,
• wherein a sampling frequency of the second ΔΣ modulator is higher than a sampling frequency of the first ΔΣ modulator.

A ΔΣ modulation device comprising:

• a first ΔΣ modulator comprising an integrator for integrating an analog input signal, a quantizer for quantizing an output signal from the integrator, and a first adder for inverting the polarity of an output signal from the quantizer and adding the inverted output signal to the analog input signal;
• a second adder for inverting the polarity of either the output signal from the quantizer of the first ΔΣ modulator or the output signal from the integrator of the first ΔΣ modulator, and adding the inverted signal to the other of the signals;
• a second ΔΣ modulator for modulating a signal output from the second adder;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the second ΔΣ modulator and the digital signal output from the quantizer of the first ΔΣ modulator,
• wherein a sampling frequency of the second ΔΣ modulator is higher than a sampling frequency of the first ΔΣ modulator.

A ΔΣ modulation device comprising:

• a first ΔΣ modulator comprising an integrator for integrating an analog input signal, a first quantizer for quantizing an output signal from the integrator, and a first adder for inverting the polarity of an output signal from the first quantizer and adding the inverted output signal to the analog input signal;
• a second adder for inverting the polarity of either the output signal from the first quantizer of the first ΔΣ modulator or the output signal from the integrator of the first ΔΣ modulator, and adding the inverted signal to the other one of the signals;
• an oscillator for changing a frequency thereof according to a signal from the second adder;
• a second quantizer for quantizing an output signal from the oscillator;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the second quantizer and the digital signal output from the first quantizer of the first ΔΣ modulator,
• wherein a sampling frequency of the second quantizer is higher than a sampling frequency of the first ΔΣ modulator.

A ΔΣ modulation device comprising:

• a first ΔΣ modulator comprising an integrator for integrating an analog input signal, a quantizer for quantizing an output signal from the integrating means, and an adder for inverting the polarity of an output signal from the quantizer and adding the inverted output signal to the analog input signal;
• a second ΔΣ modulator for modulating the signal output from the integrator of the first ΔΣ modulator;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the second ΔΣ modulator and the digital signal output from the quantizer of the first ΔΣ modulator,
• wherein a sampling frequency of the second ΔΣ modulator is higher than a sampling frequency of the first ΔΣ modulator.

A ΔΣ modulation device comprising:

• a first ΔΣ modulator comprising an integrator for integrating an analog input signal, a first quantizer for quantizing an output signal from the integrator, and a adder for inverting the polarity of an output signal from the first quantizer and adding the inverted output signal to the analog input signal;
• an oscillator for changing a frequency thereof according to a signal output from the integrator of the first ΔΣ modulator;
• a second quantizer for quantizing an output signal from the oscillator;
• and
• an operation circuit for applying a predetermined operation to a digital signal output from the second quantizer and the digital signal output from the first quantizer of the first ΔΣ modulator,
• wherein a sampling frequency of the second quantizer is higher than a sampling frequency of the first ΔΣ modulator.

A ΔΣ modulation device comprising:

• a first oscillator for changing a frequency thereof according to an input signal;
• a second oscillator for changing a frequency thereof according to the input signal;
• a first quantizer for quantizing a frequency modulation signal output from the first oscillator;
• a second quantizer for quantizing a frequency modulation signal output from the second oscillator;
• and
• a processor for processing digital signals output respectively from the first and second quantizer,
• wherein either the first oscillator or the second oscillator has a positive frequency dependency to the input signal, and the other has a negative frequency dependency to the input signal.