HFF Voltage-Controlled Crystal Oscillators CTS HFF Voltage-Controlled Crystal Oscillators (VCXOs) are high-frequency fundamental crystal oscillators with clock rates up to 250MHz. The CTS HFF VCXOs offer excellent stability and low jitter/phase noise performance. Available in 5mm x 3.2mm and 7mm x 5mm case sizes, the HFF series offers HCMOS, LVPECL, or LVDS outputs. These VCXOs are ideal for use in small cell, wireless, broad access, base station, digital video, and test/measurement applications.