Impedance-to-digital converter, impedance-to-digital converting device, and method for adjustment of impedance-to-digital converting device

An impedance-to-digital converting device for sensing an impedance value of a to-be-sensed component, comprising:

• an impedance-to-digital converter including:
• a sensing unit to be coupled to the to-be-sensed component, disposed to receive a sensing voltage and a sensing current, operable to select one of the sensing voltage and the sensing current to be a sensing signal, and configured to provide the sensing signal to the to-be-sensed component, and to convert the sensing signal into a first electric charge every operation period of said impedance-to-digital converter, an amount of the first electric charge being proportional to a magnitude of the sensing signal;
• an offset impedance unit disposed to receive an offset signal, and configured to convert the offset signal into a second electric charge every operation period of said impedance-to-digital converter, an amount of the second electric charge being proportional to a magnitude of the offset signal;
• a reference impedance unit disposed to receive a reference signal and a digital signal that has a series of logic values, and including a reference impedance circuit configured to convert the reference signal into a third electric charge every operation period of said impedance-to-digital converter, an amount of the third electric charge being proportional to a magnitude of the reference signal, a polarity of the third electric charge being associated with a logic level of the digital signal;
• and
• a conversion block receiving the first electric charge, the second electric charge and the third electric charge that are respectively outputted by said sensing unit, said offset impedance unit and said reference impedance unit to cooperatively form a resultant electric charge, and configured to convert the resultant electric into the digital signal;
• and
• an operation unit coupled to said conversion block for receiving therefrom the digital signal, and configured to perform an average operation of the series of logic values of the digital signal to generate a series-average value;
• wherein said operation unit includes a lookup table recording a pre-stored impedance value that corresponds to the series-average value thus generated, and is further configured to obtain the pre-stored impedance value from said lookup table according to the series-average value, and to output the pre-stored impedance value to serve as a sensed impedance value corresponding to the to-be-sensed component;
• wherein the impedance value sensed by said impedance-to-digital converting device has a linear relationship with a number of the operation periods that correspond to a predetermined logic level of the digital signal among a predetermined number of the operation periods;
• wherein a central value of a sensible impedance range of said impedance-to-digital converter is proportional to a ratio of a magnitude of the offset signal to a magnitude of the sensing signal;
• wherein the impedance value sensed by impedance-to-digital converting device has a sensing resolution proportional to a ratio of the magnitude of the sensing signal to a magnitude of the reference signal.