In this manuscript, we propose and experimentally demonstrate a dispersion-controlled optoelectronic oscillator with phase only modulator at 18 GHz. The generated microwave signal has a phase noise of −108 dBc/Hz at 10 kHz offset frequency and the integrated timing jitter is calculated to be 16.2 fs (1 kHz to 100 MHz) and 20 fs (1kHz to Nyquist).