bipolar device simulation parameter

[zarric]

what is the difference between device area and multiplier in bipolar device paremeter.
in my opinion, device area is the emitter area coefficient ( for example : merged two 8*8 emitter area in a 8*16) and multiplier is the paralled device number??
whether that is correct????

thanks all

 

[diemilio]

In spice:

Scaling is controlled by the element parameters AREA, AREAB, AREAC, and M. The AREA parameter, the normalized emitter area, divides all resistors and multiplies all currents and capacitors. AREAB and AREAC scale the size of the base area and collector area. Either AREAB or AREAC is used for scaling, depending on whether vertical or lateral geometry is selected (using the SUBS model parameter). For vertical geometry, AREAB is the scaling factor for IBC, ISC, and CJC. For lateral geometry, AREAC is the scaling factor. The scaling factor is AREA for all other parameters.

M is just a multiplier that accompanies the parameter AREA (in every single equation). For example, The following formula scales the DC model parameters (IBE, IS, ISE, IKF, IKR, and IRB) for both vertical and lateral BJT transistors:

Ieff = AREA ⋅ M ⋅ I

Reference: SPICE Elements and Device Models Manual

Hope this helps,

diemilio

By the way, M is what you call "multiplier parameter".