Measurement apparatus and measurement method
There is realized a measurement apparatus capable of highly accurate synchronous detection while keeping costs low. A measurement apparatus is characterized by including: a current generation circuit causing an alternating constant current corresponding to a reference signal (Ss) with a predetermined frequency to occur and supplying the alternating constant current to a measurement target object; a voltage detection circuit detecting a voltage v that has occurred in the measurement target object; a signal generation circuit detecting a current i flowing in the measurement target object and generating a binary signal (Sip) synchronized with the current i; a first synchronous detection unit performing synchronous detection of the voltage v based on the reference signal (Ss) and calculating an amplitude |V| of the voltage v and a voltage phase difference φv; a second synchronous detection unit performing synchronous detection of the binary signal (Sip) based on the reference signal (Ss) and calculating a current phase difference φi; and an arithmetic unit calculating electrical characteristics of the measurement target object based on the amplitude |V| of the voltage and the voltage phase difference φv, the current phase difference φi, and an amplitude |I| of the current.
1 . A measurement apparatus comprising:
a current generation circuit causing an alternating constant current corresponding to a reference signal with a predetermined frequency to occur and supplying the alternating constant current to a measurement target object;
a voltage detection circuit detecting a voltage that has occurred in the measurement target object;
a signal generation circuit detecting a current flowing in the measurement target object and generating a binary signal synchronized with a phase of the detected current, the binary signal synchronized with only a phase of the detected current;
a first synchronous detection unit performing synchronous detection of the voltage detected by the voltage detection circuit, based on the reference signal and calculating an amplitude of the voltage and a voltage phase difference that is a phase difference between a phase of the voltage and a phase of the reference signal;
a second synchronous detection unit performing synchronous detection of the binary signal based on the reference signal and calculating a current phase difference that is a phase difference between the phase of the detected current flowing in the measurement target object and the phase of the reference signal; and
an arithmetic unit calculating electrical characteristics of the measurement target object based on the amplitude of the voltage and the voltage phase difference calculated by the first synchronous detection unit, the current phase difference calculated by the second synchronous detection unit, and an amplitude of the current flowing in the measurement target object, wherein the signal generation circuit compares a voltage signal obtained by converting the current flowing in the measurement target object to a reference voltage and generates the binary signal representing a binary comparison result.
2 . The measurement apparatus according to claim 1 , further comprising a communication circuit performing, in a state of a first circuit side including the signal generation circuit and a second circuit side including the first synchronous detection unit, the second synchronous detection unit, and the arithmetic unit being electrically insulated from each other, transmission/reception of signals between the first circuit side and the second circuit side.
3 . The measurement apparatus according to claim 1 , wherein the signal generation circuit compares a voltage signal obtained by converting the current flowing in the measurement target object to a voltage and a reference voltage and generates the binary signal corresponding to a result of the comparison.
4 . The measurement apparatus according to claim 1 , wherein
the first synchronous detection unit calculates the amplitude of the voltage and the voltage phase difference by multiplying a digital signal of the voltage detected by the voltage detection circuit and a digital signal indicating the reference signal and multiplying the digital signal of the voltage detected by the voltage detection circuit and a digital signal with a phase displaced by 90° relative to the reference signal, and
the second synchronous detection unit calculates the current phase difference by multiplying the binary signal and the digital signal indicating the reference signal and multiplying the binary signal and the digital signal with the phase displaced by 90° relative to the reference signal.
5 . A measurement method comprising:
a first step of, by performing synchronous detection of a voltage that occurs in a measurement target object when an alternating constant current corresponding to a reference signal with a predetermined frequency is supplied to the measurement target object, based on the reference signal, calculating an amplitude of the voltage and a voltage phase difference that is a phase difference between a phase of the voltage and a phase of the reference signal;
a second step of generating a binary signal synchronized with a phase of a current flowing in the measurement target object when the constant current is supplied to the measurement target object, the binary signal synchronized with only a phase of the current flowing in the measurement target object, the second step including comparing a voltage signal obtained by converting the current flowing in the measurement target object into a reference voltage and generating the binary signal representing a binary comparison result;
a third step of, by performing synchronous detection of the binary signal generated at the second step, based on the reference signal, calculating a current phase difference that is a phase difference between the phase of the current flowing in the measurement target object and the phase of the reference signal; and
a fourth step of calculating electrical characteristics of the measurement target object based on the amplitude of the voltage and the voltage phase difference calculated at the first step and the current phase difference calculated at the third step.