In RFID system, when multiple tags transmit information in the same wireless channel simultaneously, data collisions usually occur which will reduce the identifying efficiency of RFID systems. To resolve this problem, several Dynamic Frame-Slotted ALOHA (DFSA) methods have been proposed. However, these methods are generally not capable of achieving expected performance when the number of tags is much larger or smaller than the initial frame size. Aiming to this problem, a Rapid DFSAI (RDFSAI) method was put forward based on the DFSA with interrupt (DFSAI) in this paper. Firstly, whether the frame size is adjusted or not is judged by comparing the system efficiency with the reference system efficiency. Secondly, the multiple factor of the frame size is determined by the ratio between the collision and empty slots, which leads to a seriels of different multiple factors or. As a result, the proposed RDFSAI elevates the adjustment speed of frame size and reduces the unnecessary empty and collision slots effectively. Simulation results indicate that the RDFSAI method appears better performance than the conventional methods even the tag number is increased up to 1600.

An implementation method of a power supply on-chip (PSOC) was presented for low power digital integrated circuit (IC) applications in this paper. The PSOC consists of a main power supply and a backup low power dissipation power supply, which is featured of micro-standby power consumption and fast switching. The PSOC was designed according to the design rules of SMIC 0.18μm CMOS process and validated both through simulation and silicon verification. The active area is about 0.035mm2 in fact. Post-layout simulation results indicate that output voltage of the PSOC is regulable in the range of 1.52~2.5V as input voltage is in the range of 2.0~3.6V, in which output of the main power supply is regulable in the range of 1.75~ 1.84V. The maximum quiescent current of main power supply is 16.23μA, while the maximum quiescent current of standby power is only 0.552μA. Experimental results indicate that the PSOC is capable of providing energy for the system digital IC implementation. Its power switching time is less than 148μs at the load capacitance of CL =56nF.