| MOS |
BIPOLAR |
| Majority-carrier device |
Minority-carrier device |
| No charge-storage effects |
Charge stored in the base and collector |
| High switching speeds, less temperature sensitive than bipolar devices |
Low switching speed, temperature sensitive |
| Drift current (fast process) |
Diffusion current (slow process) |
| Voltage Driven |
Current Driven |
| Purely capacitive input impedance; no DC current required |
Low input impedance; DC current required |
| Simple drive circuitry |
Complex drive circuitry (resulting from high base current requirements) |
| Predominently negative temperature coefficient on resistance |
Positive temperature coefficient of collector current |
| No thermal runaway |
Thermal runaway |
| Devices can be paralleled with some precautions |
Devices cannot be simply paralleled because of VBE matching problems and local current concentration |
| Less susceptible to second breakdown |
Susceptible to second breakdown |
| Square-law I-V characteristics at low current; linear I-V features at high current |
Exponential I-V characteristics |
| Greater linear operating and fewer harmonics |
More intermodulation and cross-modulation products |
| Low on-resistance (low saturation voltage) because of conductivity modulation of high resistivity drift region |
High on-resistance and therefore larger conduction loss |
| Drain current proportional to channel width |
Collector current approximately proportional to emitter stripe length and area |
| Low transconductance |
High transconductance |
| High breakdown voltage as the result of a lightly doped region of a channel-drain blocking junction |
High breakdown voltage as the result of a lightly doped region of a base collector blocking junction |
