Patent ID: 9572949
Date: 2017-02-21
CPC Classifications: A61M,G01K

Claim:
1. A sensing circuit for a heated conduit for use in a respiratory apparatus, the sensing circuit comprising: a sensing wire coupled to a heating circuit for the heated conduit; a temperature sensor coupled to the sensing wire and configured to measure the temperature of the heated conduit; a sensing resistor coupled to the sensing wire and configured to provide an output to indicate the temperature measured by the temperature sensor; and a bias generator circuit configured to provide a reference voltage to the sensing resistor to allow determination of the output as a function of a voltage drop across the sensing resistor during both heating on and heating off cycles of the heating circuit, wherein the bias generator includes a track and hold circuit configured to measure a voltage of the sensing wire and provide the measured voltage to the bias generator circuit, wherein the bias generator circuit is configured to adjust the reference voltage as a function of the measured voltage.