Embodiments of the present invention provide a packet receiving method, a deep packet inspection device and system, which relates to the field of communications. The latch circuit includes four or more inverters connected in a loop to hold a signal, a plurality of input terminals respectively connected to different nodes, and a plurality of output terminals respectively connected to different nodes. Embodiments having single and paired cavities in the piston head are disclosed. The apparatus has a means for producing the alternating field and a means for transmitting the alternating field. The bridge layout connects the first and second peripheral line layouts and overlaps the misaligned contact layout.