In order to meet the need to measure the changing resistance signal during the test

a fast sampling interface circuit with a wide dynamic range for high-sensitivity nanomaterial gas sensors is designed. Based on the principle of integral circuit

this circuit converts the current flowing through the sensor into a square wave signal which has a certain pulse width

and then uses microcontroller unit（ MCU） to capture pulse time and convert into resistance value. The circuit has a maximum linearity error of 5 % in measurement range of 1 kΩ～ 500 MΩ and can be used in gas sensor testing or calibration

handheld gas detection equipment

and resistance measurement field.