In this work, a compact model based on an analytical closed form solution of the 1D Poisson's equation for a double-gate Tunnel FET is derived. Furthermore, the current levels are estimated by implementing an algorithm based on the Kane's band-to-band tunneling model. A good agreement with numerical simulations for varying device parameters is demonstrated and the advantages and limitations of the modeling approach are investigated and discussed. The model is implemented in a Verilog-A based circuit simulator and basic circuit blocks like an inverter, a 2-bit half adder and a 15 stage ring oscillator are simulated to demonstrate the capabilities of the model. The switching energy of a Tunnel FET based circuit block is studied with Vdd scaling revealing interesting aspects of Tunnel FET circuit behavior.