Proto-type commercial grade Silicon Drift Detectors (SDDs) with on-chip low noise JFETs have been realized using silicon bipolar technology at Bharat Electronics Ltd (BEL), Bangalore. Noise analysis articulating the relationships of various noise sources on the electrical parameters of the fabricated SDD and JFET have been discussed. TCAD device simulations have been performed for the SDD and on-chip JFET for static (dc) and dynamic cases. The static case simulations revealed values of critical dc performance parameters like leakage current, anode capacitance etc. Dynamic simulations meant to study the effect of radiation, revealed the relationship between drift time & drift distance within the detector. Analytical modeling of the I-V characteristics of the SDD has also been performed to predict the leakage current behavior for various other designs fabricated at BEL.