A detailed Sentaurus TCAD simulation based study for Silicon Double Gate Tunnel Field Effect Transistor (Si-DG TFET) based Ring Oscillator (RO) is presented in this work. Two different ring oscillator topologies (simple RO and Negative Skewed Delay RO )are presented with two different structures for TFET device. The two structures are different in the source-drain extension regions widths. The extension region width variation effects are studied and presented for inverter and ring oscillator. A TFET based inverter is presented to show the changes in behavior due to variations in the drain extension region widths, which is later used for RO designs. The drain extension region width changes the drain extension region resistances which in turn is responsible for change in the corresponding device properties. RO simulation are used for calculating the delay. To further explore digital and analog applications transfer characteristics and noise margins of inverter are explored with power supplies variations. Better reliability for oscillation frequency is obtained using Negative Skewed Delay ring oscillator (NSD RO) topology. NSD RO is resulting in lesser jitter, more reliable frequency as compared to single-ended ring oscillator topology. By tuning the supply voltage of the device the ring oscillator frequency can be used for RF applications, thus it works like a voltage controlled oscillator (VCO).