Combined amplifier circuit

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As mentioned above, the three basic configuration amplifier circuits have their own advantages and disadvantages. If two of the configuration circuits are properly combined to form a combined amplifier circuit, the performance will be highly complementary. This section discusses several commonly used combined amplifier circuits.

2.5.1 Common-emitter-common-base combination amplifier circuit

The right figure is a common emitter-common base combined amplifier circuit: T1 forms a common emitter circuit with a higher input resistance and current gain; T2 forms a common base circuit with a higher voltage gain and output resistance R0 '. Therefore, the circuit has a higher power gain and a wider frequency band.

Common emitter-common base combination amplifier circuit

The figure below is its slightly variable equivalent circuit, where R _b = R _b1 ∥ R _b2 .

The slightly modified equivalent circuit of the circuit in the figure above

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