Compact modeling of collector base junction space charge region transit time effect on noise in SiGe HBTs

Correlated noise in bipolar transistors: Model implementation issues

“…The extracted low-current transit time was s f 0 ¼ 0:285 ps; therefore, the BC-SCR delay can be regarded relevant in this device. Calculating the BC-SCR delay using the extracted s c0 ¼ 0:148 ps and considering the active g m -factor, we found a it ¼ 0:39 for the model (34). On the other hand assuming s c0 ¼ 0, we obtain a it ¼ 0:68 for the same model with active g m -factor.…”

“…6 and 7 allows us to use the pure NQS noise model with h c ¼ 0 in (32) and (34) even to include the SDEC affected noise response for any h c value. This further allows a simpler parameter (a it ) extraction and simultaneously preserving the model parameter count.…”

“…Here, f c replaces the commonly used notation k [18,34,35] to avoid confusion. The delay time within the BC-SCR is obtained as [33] s c ¼ s c0 Á cc;…”

Effect of Boundary Conditions on Thermal Noise of Intrinsic Terminal Currents in Bipolar Transistors Pertinent to Quasi-Ballistic Transport

“…This suggests that in device modeling and circuit design, one can continue to use the classic 2q I C for S ic in thin base transistors despite the large effect of QBT on I C itself, perhaps with a justified use of a correction coefficient. This also serves as basis of modeling the effect of CB SCR transport on transistor noise at high frequencies [3], [12], [13].…”

“…The noise comes from: 1) injection noise in the electron current injected from the emitter and emitter-base space charge region (EB SCR) and 2) diffusion noise due to inelastic scattering inside quasi-neutral base (QNB). The collector-base space region (CB SCR) does not introduce extra noise but modifies the PSDs [3], [12], [13] and will not be discussed here. The diffusion noise is well described by van Vliet model for long base, but is expected to be reduced for short base with QBT as high-velocity carriers do not contribute noise.…”