We have characterized the radio frequency (rf) noise in high-k Al2O3 and AlTiOx gate dielectrics, which have respective effective oxide thickness (EOT) of 17.2 and 12.5 Angstrom. The measured noise figure in gate dielectric is material dependent and sensitive to dielectric defect after stress. Although the high-k AlTiOx gate dielectric has lower EOT, it has a higher noise figure than others. From the simulation in our proposed equivalent circuit model, the dominant noise is thermal noise and the reason for increasing noise figure after stress is due to additional parallel resistance by trap-assisted tunneling.