Nanoscale field emission devices are promising candidates to design high-frequency electronics due to the lack of scattering in the vacuum channel that enables ballistic transport. In-plane devices are relatively easy to fabricate with current fabrication techniques and offer sub-fF capacitance. In this work, the characteristics of lateral gold multi-tip field emission arrays are studied. Vacuum gaps between the electrodes of 30 nm are fabricated, which allow < 10 V operation. The effect of number of emitting tips on measured current is investigated. By taking advantage of the strong non-linearity in the emission characteristic, frequency mixing in the MHz range is also demonstrated.