A/D converter and sensor apparatus including the same

An A/D converter comprising:

• an adder that calculates a difference between an analog input signal and a predicted value;
• a quantizer that quantizes the difference output from the adder to convert the analog input signal to a digital signal;
• a prediction filter that generates a predicted value from the digital signal output from the quantizer;
• and
• a D/A converter that converts the predicted value from a digital signal to an analog signal and output the predicted value to the adder;
• wherein
• the predicted value before being subjected to conversion to the analog signal by the D/A converter defines and functions as an A/D converted output of the analog input signal input to the adder;
• and
• the prediction filter includes:
• a second adder that calculates a difference between a value obtained by multiplying the predicted value generated by the prediction filter by a first coefficient not greater than one and an input of the prediction filter;
• an integrator that integrates an output of the second adder;
• and
• a third adder that calculates a difference between a value obtained by multiplying the predicted value generated by the prediction filter by a second coefficient not greater than one and an output of the integrator to generate the predicted value.

A sensor apparatus comprising:

• an A/D converter including:
• an adder that calculates a difference between an analog input signal and a predicted value;
• a quantizer that quantizer the difference output from the adder to convert the analog input signal to a digital signal;
• a prediction filter that generates a predicted value from the digital signal output from the quantizer;
• and
• a D/A converter that converts the predicted value from a digital signal to an analog signal and output the predicted value to the adder;
• wherein
• the predicted value before being subjected to conversion to the analog signal by the D/A converter defines and functions as an A/D converted output of the analog input signal input to the adder;
• the adder is a capacitance adder including a series circuit including a capacitive charge output sensor and a capacitor;
• and
• a connection point between the capacitive charge output sensor and the capacitor is connected to an input of the quantizer.