APPENDIX FTransistor and Amplifier Formulas
The following formulas are meant as a reminder of the fundamentals given in most standard electronics textbooks. Notation for the formulas have the traditional meanings. Depletion capacitances are all given with a negative sign in the denominator as in C = C0/(1 − V/ϕ)γ. Consequently, when the junction is reverse biased, the minus sign turns into a positive sign. Figure F.1 presents the basic FET features and symbols. The transistor body terminal typically is connected to the source or to ground. When the source is not grounded, the body effect modifies the transistor properties. The equations using the Early voltage, VA, should conform with the sign convention used by SPICE (VA > 0).
FIGURE F.1 FET symbols.
BIPOLAR TRANSISTOR PARAMETERS (BJT)
| Description | Formula |
| Collector current |
|
| Transconductance |
|
| Input resistance |
|
| Output resistance |
|
| Base charging capacitance | CD = τFgm |
| Emitter–base junction | |
| Input capacitance ... |
