23rd IMEKO TC 4 International Symposium and the 5th Chinese Conference on Electromagnetic Metrology Technical (IMEKO TC4 2019)

176 / 2019-03-24 14:55:05

A High Isolation Analogue Switch and its Application in Digital Sampling Bridge

Analog switch,Off-Isolation,Impedance bridge,Sampling method

Plenary track > Signal and Image processing

This paper describes a high-isolation analogue switching device to replace the mechanical reed switches used in precision digital sampling bridges. The switching speed of the designed analogue switch is much higher than that of the mechanical switches, and the Off-Isolation is good enough at frequencies between 1 kHz and 100 kHz. A method of applying the designed analogue switch to an automatic source balanced single digital sampling bridge is given, the theoretical measurement accuracy of the given bridge can reach ppm level with faster measurement speed. Finally, the actual Off-Isolation of the designed switch is verified by the method of detecting the small signal by the lock-in amplifier. The designed switch has a simple structure, is convenient and practical, and simplifies the design of the impedance bridge, it has been successfully applied to a digital sampling bridge developed at NIM