415
Bipolar Junction Transistor Compact Models
A complete set of SGP BJT compact model parameters is extracted from
the following set of measurement data set for BJT parameter extraction
including:
• Forward characteristics
• Gummel plot (I C , I B ) versus V BE with V BC = 0
• I C versus V CE
• Cut-off frequency, f T versus I C
• Reverse characteristics
• Gummel plot (I E , I B ) versus V EB with V BE = 0
• I E versus V CE
The SGP model does not model the devices in the reverse mode as accurately
as in the forward mode. Though BJTs are normally operated in the forward
mode, both forward and reverse data are needed to extract series resistances.
In addition EB and CB pn-junction structures are used to extract capacitance model parameters {C j0 , f bi , m j }.
11.6 Summary
This chapter presented the basic BJT model for circuit simulation. A systematic methodology is presented to derive SGP BJT compact model starting
from the basic EM model. An overview of the model parameter extraction
is presented. The objective of this chapter is to expose readers to the basic
understanding of BJT device modeling. The readers involved in BJT device
engineering can extend the basic understanding from this study to more
appropriate advanced BJT models.
Exercises
11.1 An npn-BJT is used as an open-collector pn-junction diode as
shown in Figure E11.1. Then
a. Use the injection version of EM1 BJT model to derive an expression for the emitter current I E as a function of V BE ;
b. Use the expression derived in part (a) to calculate V BE for I E = −1 mA.
Given that: α F = 0.98; α R = 0.49; I ES = 10 −16 A, and T = 300 K.
Bipolar Junction Transistor Compact Models
A complete set of SGP BJT compact model parameters is extracted from
the following set of measurement data set for BJT parameter extraction
including:
• Forward characteristics
• Gummel plot (I C , I B ) versus V BE with V BC = 0
• I C versus V CE
• Cut-off frequency, f T versus I C
• Reverse characteristics
• Gummel plot (I E , I B ) versus V EB with V BE = 0
• I E versus V CE
The SGP model does not model the devices in the reverse mode as accurately
as in the forward mode. Though BJTs are normally operated in the forward
mode, both forward and reverse data are needed to extract series resistances.
In addition EB and CB pn-junction structures are used to extract capacitance model parameters {C j0 , f bi , m j }.
11.6 Summary
This chapter presented the basic BJT model for circuit simulation. A systematic methodology is presented to derive SGP BJT compact model starting
from the basic EM model. An overview of the model parameter extraction
is presented. The objective of this chapter is to expose readers to the basic
understanding of BJT device modeling. The readers involved in BJT device
engineering can extend the basic understanding from this study to more
appropriate advanced BJT models.
Exercises
11.1 An npn-BJT is used as an open-collector pn-junction diode as
shown in Figure E11.1. Then
a. Use the injection version of EM1 BJT model to derive an expression for the emitter current I E as a function of V BE ;
b. Use the expression derived in part (a) to calculate V BE for I E = −1 mA.
Given that: α F = 0.98; α R = 0.49; I ES = 10 −16 A, and T = 300 K.