Two or more transistors can be wired together to create a new single transistor. This hybrid transistor has better characteristics
compared to each one of the transistors used. The advantages are higher collector impedance and lower sensitivity to noise at the input.
The cascaded transistors approximate the function of a constant current source.
The first circuit shown uses two transistors, and the second one uses a combination of transistor and FET. The FET combination offers a much less critical DC voltage stabilization.
Electronic Circuits volume 1.0 - Circuit Nr. 16
The complete data of the electronic circuit described above can be found in the following book and is available from Amazon.com.
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