UHF passive RFID tags have become a natural option for long distance identification (few meters) as warehouse monitoring and vehicles control access. However, ultra-high frequency and long distance identification implies in very low received power. In order to achieve low power and reliability, a 1.4 V and 300 nA UHF passive RFID voltage regulator was designed in 130 nm CMOS. According to electric simulations of TT corner, we found a voltage regulation settling time smaller than 1 ms for a temperature coefficient of 220 ppm/°C. The voltage reference variability is μ= 712 mV and σ= 45 mV, estimated by a 1k points MC electric simulation. Finally, we found a PSRR smaller than -30 dB at 100 Hz, 27°C.