Impedance measuring device and method

An impedance measuring device comprising:

• a signal generation unit that generates a first reference signal, and a second reference signal that is obtained by inverting a phase of the first reference signal at an interval of a predetermined inversion period;
• a measurement signal supply unit that produces a measurement signal, based on the second reference signal, and supplies the measurement signal to a measurement object;
• a measuring unit that synchronously detects a signal occurring in the measurement object due to the measurement signal, using a modulation signal produced based on the second reference signal, and further produces a filtered signal by low-pass filtering the detected signal;
• and
• an arithmetic unit that determines impedance of the measurement object, based on an added average of a magnitude of the filtered signal when the first reference signal and the second reference signal are in phase, and a magnitude of the filtered signal when the first reference signal and the second reference signal are in anti-phase.

A method comprising steps of:

• generating a first reference signal, and a second reference signal that is obtained by inverting a phase of the first reference signal at an interval of a predetermined inversion period;
• producing a measurement signal, based on the second reference signal, and supplying the measurement signal to a measurement object;
• synchronously detecting a signal occurring in the measurement object due to the measurement signal, using a modulation signal produced based on the first reference signal, and further producing a filtered signal by low-pass filtering the detected signal;
• and
• determining impedance of the measurement object, based on an added average of a magnitude of the filtered signal when the first reference signal and the second reference signal are in phase, and a magnitude of the filtered signal with inverted sign when the first reference signal and the second reference signal are in anti-phase.

A method comprising steps of:

• generating a first reference signal, and a second reference signal that is obtained by inverting a phase of the first reference signal at an interval of a predetermined inversion period;
• producing a measurement signal based on the second reference signal, and supplying the measurement signal to a measurement object;
• synchronously detecting a signal occurring in the measurement object due to the measurement signal, using a modulation signal produced based on the second reference signal, and further producing a filtered signal by low-pass filtering the detected signal;
• and
• determining impedance of the measurement object, based on an added average of a magnitude of the filtered signal when the first reference signal and the second reference signal are in phase, and a magnitude of the filtered signal when the first reference signal and the second reference signal are in anti-phase.