In this study, a new voltage mode frequency agile filter designed by voltage differencing trans-conductance amplifier (VDTA) is presented. A single VDTA and two capacitors are used to implement the designed frequency agile filter. The MOS capacitor technique is used instead of conventional capacitors to achieve high operating frequencies. The agility of the designed filter is implemented by selecting different size MOS capacitor. The performance parameters of the VDTA and agile filter structure are summarized. The suitability of the filter for different applications are given. AMS 0.18 mu m parameters are used for the designed frequency agile filter.