Signal extraction circuits and methods for ion mobility tube, and ion mobility detectors

An ion mobility detector, comprising:

• an ion mobility tube operable to characterize ions from an ion source by detecting mobility of the ions in an electric field;
• a signal extraction circuit, comprising a DC blocking module provided with a signal leadin terminal and a signal leadout terminal, wherein the signal leadin terminal in the signal extraction circuit is electrically connected to a Faraday plate in the ion mobility tube, and the DC blocking module is configured to block a high voltage bias signal contained in a voltage from the Faraday plate while passing a time-varying low voltage waveform contained in the voltage extracted from the Faraday plate representing ions received at the Faraday plate as a result of the high voltage bias signal applied to the Faraday plate;
• a pulsed voltage processing circuit electrically connected to the signal leadout terminal and operating at a low voltage, the pulsed voltage processing circuit being configured to perform amplification and/or analog-to-digital conversion on the pulsed voltage output from the signal leadout terminal, wherein an outer shield hood and an inner shield hood are further provided in the ion mobility tube;
• the Faraday plate comprises first and second sides located opposite to each other, and the first side is configured to receive ions;
• the outer shield hood is disposed covering the Faraday plate, and a convex part of the outer shield hood is located opposite to the second side of the Faraday plate;
• the Faraday plate is electrically connected to an inner core of a first coaxial cable via a connection core wire;
• the inner shield hood is located inside the outer shield hood, and a convex part of the inner shield hood is located opposite to the second side of the Faraday plate and disposed covering the connection core wire;
• the inner core of the first coaxial cable is electrically connected in parallel to the signal leadin terminal and a first power supply terminal of the ion mobility tube, respectively;
• both ends of a first outer conductor of the first coaxial cable are electrically connected to the outer shield hood and a second power supply terminal of the ion mobility tube, respectively;
• both ends of a second outer conductor of the first coaxial cable are electrically connected to the inner shield hood and the first power supply terminal, respectively.