first diffuse to the transition region before producing a measurable change in current, which adds an additional strongly expressed diffusive pole into all of the TES transfer functions. In a phase separated CDMS-II TES device for example, measured $\frac{\partial I_{t}}{\partial V_{b}}$ has 2 fall-time poles (plus the $R/L$ pole) with roughly similar weighting [@MCP_Thesis]. Beyond simply adding confusion when trying to understand and model device performance, the most important consequence is to again suppress $\omega_{S/N \, \delta \! P_{t}}$.

Finally, due to such large variations in the derivative of the resistivity ($\frac{\partial \rho}{\partial T}$) across the sharp superconducting/normal boundary, thermal power fluctuations within the TES directly couple to the total TES resistance $R_{t}$, and consequently the measured signal current $I_{t}$, giving us an additional noise source with fluctuations on all length scales [@circleTES]. Interestingly enough, in discretized simulations of phase separated TES for CDMS-II [@MCP_Thesis], we have found that this additional noise source is largely counter balanced by a suppression in sensitivity to standard TFN noise across $G_{tb}$ at frequencies below the longest diffusive pole, and thus $S_{p\, total}$ primarily sees increases at higher frequencies.

Bandwidth Mismatch between Signal and Sensor {#sec:BandwidthMismatch}
============================================

Before attempting to estimate the sensitivity of 