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Figure 2.34 Operating conditions of constant current sink.

Plotting Va=204 V, Ia=0 mA is easy, but we don’t yet know where the other end of the loadline will be. However, we do know a point on the line; we know that Ia=2 mA at the operating point, although we do not know the voltage. It is up to us to choose a voltage, and Va=81 V is a good choice for linearity. Linearity is still important in a CCS because the complete circuit will probably modulate the sink’s anode voltage with an audio signal. If linearity is poor, this indicates non-constant ra, which is part of the term that governs the output resistance of the sink. If the output resistance ...

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