A single branch charge pump without overstress for RFID tag

Charge pump, which provides high voltage to program the memory cells, is indispensable for the nonvolatile memory (NVM) in radio frequency identification (RFID) tag. This paper presents a charge pump, which adopts single branch topology and is implemented only with PMOSFETs, to fulfill the low cost requirement of RFID tag. By introducing a voltage shift circuit, the voltage difference of adjacent nodes in the charge pump will not exceed the supply voltage (V_dd), which ensures the reliability of charge pump. Furthermore, the bulks of transmission transistors in the charge pump connect with the sources of that by resistances, which can drop the peak of power consumption at the settling time efficiently. A 10 stages charge pump of the proposed topology is implemented in a 0.18-um CMOS standard process, which can pump the supply voltage of 1.5 V to 14.89 V with pure capacitor load at clock frequency of 2 MHz. The charge pump consumes an active die area of 146×76 um².