In order to precisely measure the volume fraction of methane to avoid explosion accident’s occurrence

a signal conditioning circuit for a thermal conductivity sensor is designed based on the thermal conductivity sensor TCS208F

instrumentation amplifier INA122

U/I transmitter AD694.The weak voltage signal obtained by sensor is amplified

converts into 4

2

0mA industrial standard electric current signal which suites for long-distance transmission after the U/I transformation.Electric current signal is converted back to voltage signal

and sends it into the monolithic integrated circuit.Aimed at question appeared in the circuit design process

the analysis is carried on to circuit design’s disturbance factor

a series of anti-jamming measure is obtaind

and the goo

d effect is obtained.