Patent ID: 8659305

Claim:
A detection device for detecting an element impedance of a sensor element comprised of a solid electrolyte, comprising: an alternating current signal supplying section configured to supply an alternating current signal to a sensor element; and an impedance detection section configured to detect an element impedance of the sensor element on the basis of one of a current and a voltage of an impedance response signal which is transmitted from the sensor element and alternately changed in response to the alternating current signal supplied to the sensor element, wherein the impedance detection section comprises: an input comparator configured to input the impedance response signal and a hold value, to compare the impedance response signal with the hold value, and to output an output voltage on the basis of the comparison result; a hold capacitor configured to be charged by the output voltage supplied from the input comparator and to hold the hold value on the basis of the charged amount and the hold value in the hold capacitor being sequentially updated every time of an alternately changing period of the impedance response signal; and a limit section configured to adjust the output voltage of the input comparator in order to extend the time to update the hold value of the hold capacitor.