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A bipolar junction transistor (BJT) is a three-terminal device constructed of doped semiconductor material and may be used in amplifying or switching applications. Bipolar transistors are so named because their operation involves both electrons and holes. Although a small part of the transistor current is due to the flow of majority carriers, most of the transistor current is due to the flow of minority carriers, and so BJTs are classified as "minority-carrier" devices. This tool allows Bipolar Junction Transistor (BJT) simulation using a 2D mesh. It allows the user to simulate an npn- or pnp- type of device in common-emitter and common-base configurations. Users can specify the Emitter, Base and Collector region depths and doping densities. Also, the material and minority carrier lifetimes can be specified by the user.
BJT Operation Description
BJT Theoretical Exercise
Typical simulation run time LINEAR: ~ 2 minutes
Typical simulation run time DISCRETE: ~ 4 minutes
- If you want to know more about the physics of the operation of BJT plese refer to the following slides:
Example Problems for BJT:
BJT tool wish list :
- Upgrading to include HBT simulations.
Improvements / modifications in subsequent version releases:
- 2.4 - Updated mobility term for doping dependence. Added Beta Vs Ic plot.
- 2.3.3 - Fixed Vc voltage sign for npn
- 2.3.2 - Changed default input deck for run to be faster.
- 2.3.1 - Fixed overwriting for previous simulation runs
- 2.3 - Improved mesh density for Linear case around 2*Le+Wb+2*Lc (Le/c=diffusion lengths;Wb=base width). Mesh density gradient calculated depending on doping in the region for better resolution.
- 2.2 - Working for Common Base mode of operation. Added fermi level plot in equilibrium energy band diagram. Added option for minority carrier lifetime (us) and Diffusion constant (cm2/s) for Emitter,Base and Collector regions.
- 2.1 - 1D Linear BJT simulation capability added.3D plots added for better visualization for 2D discrete BJT simulations.
- 2.0.1 - Added simulation progress bar.
- 2.0 - It is now a full 2D simulator allowing users to plot 1D plots along the depth like conduction/valence band, electron/hole density, electric field, potential, recombination rate, current density.
- 1.22 - Fixed for memory issue by trimming output files.
- 1.12 - Update for improved quality of output curves. No overlapping of curves now.
- 1.11 - Discrete BJT simulator launched with output characteristics and Gummel plot.
- 1.1 - 1D linear BJT simulator updated for minor bugs.
- 1.0 - 1D linear BJT simulator launched.
PADRE (Pisces And Device REplacement) developed by Mark Pinto & Kent Smith at AT&T Bell Labs.
Cite this work
Researchers should cite this work as follows: