A novel voltage controlled oscillator (VCO) without inductances has been fabricated for the first time based on dual base transistor (DUBAT), which is normally considered as a negative resistance device. The physical model gained through the analysis of the two dimensional transportation of its internal charge carriers of this oscillator is described in detail and its equivalent circuit is introduced. The results simulated by SPICE are consistent with those of experiments. An excellent linearity of frequency versus control voltage is realized with a custom voltage range of control electrode. The simplicity of DUBAT structure and the compatibility of bipolar integrating process make this novel VCO a promising candidate for combination of VCO with functional circuits on a single silicon chip.