7.8 Frequency Limitations of Transistors

In this section we discuss the properties of bipolar transistors under high-frequency operation. Some of the frequency limitations are junction capacitance, charging times required when excess carrier distributions are altered, and transit time of carriers across the base region. Our aim here is not to attempt a complete analysis of high-frequency operation, but rather to consider the physical basis of the most important effects. Therefore, we shall include the dominant capacitances and charging times and discuss the effects of the transit time on high-frequency devices.

7.8.1 Capacitance and Charging Times

The most obvious frequency limitation of transistors is the presence of junction capacitance at ...

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