Thermal conductivity detector circuit and method for operating the same

摘要

A thermal conductivity detector (5) comprises:
a measuring cell (7) through which a sample fluid in a reference carrier fluid stream flows and which contains a detector element for generating a detector signal (11),
an amplifier (12) for amplifying the detector signal (11),
a subtracting means (13) for generating a difference signal (14) from the amplified detector signal (15) and a reference signal (16), and
a signal processing means (17, 18) for digitizing and processing the difference signal (14). To improve the thermal conductivity detector for use in gas chromatography without the need of an additional reference cell, it further comprises a reference signal generating means (19) controllable to generate the reference signal (16) from the amplified detector signal (15) or a signal derived from it in the form of a fixed analog reference value (21) at a given time when solely the reference carrier fluid passes the measuring cell (7).