We present a novel RF identification transponder based on nonlinear transmission lines (NLTLs). The NLTLs provide an effective solution to self-jamming with the harmonic generation property, and they are passive, compact, and offer easy impedance. Three NLTLs are fabricated with a different Bragg cutoff frequency fT in an IBM 8RF 0.13-μ m CMOS process. The 0.4 mm by 1.8 mm NLTL with fT = 10 GHz has -10-dBm second harmonic and -15-dBm third harmonic power with 0-dBm small-signal input. We demonstrate effective wireless transmission of the NLTL-based transponder over a read range of 0.3-0.8 m using less than 7-mm D*dot antennas and a -90-dBm off-the-shelf receiver.