A low power, fully integrated 130 nm CMOS RC oscillator for RFIDs is presented in this article. By making use of injection locking rather then a power hungry PLL, the RFID clock is locked to an external clock signal. The circuit is able to lock to a -59.3 dBm, 1.9 GHz to 2.3 GHz rf-signal which makes locking to a radiated signal received by an antenna feasible. The oscillator itself is used as a 2-fold frequency divider. This leads to an output frequency of 950 to 1150 MHz and a power consumption of 127 μW. Eight samples of the same batch were tested at different supply voltages (0.7 to 1.6 V) and temperatures (-20 to 100°C). Within the lock range, no frequency deviation was measured. The circuit was also successfully tested when driving an ultra wideband transmitter.