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[edit] Bipolar Junction Transistor (BJT) networks

The superposition theorem also is applicable for the analysis and design of the dc and ac components of a BJT network, permitting the separation of the analysis of the dc and ac responses of the system.

Circuits utilizing voltage controlled devices such as the JFET and IGFET are treated differently because transconductance functions are involved. This means that the currents flowing in different branches do not "superpose" in the usual manner (because some currents are voltage-controlled from other branches of the circuit), so superposition cannot be used directly on the complete circuit. This same limitation applies to vacuum tube circuits. Superposition Theorem The total current in any part of a linear circuit equals the algebraic sum of the currents produced by each source separately. To evaluate the separate currents to be combined, replace all other voltage sources by short circuits and all other current sources by open circuits

The above seems very confused. First, a BJT is a transconductance device too. Second, it doesn't matter. As long as the circuit is linear, superposition holds even if the sources are controlled. Please see this paper: [1] Alfred Centauri 13:38, 15 May 2007 (UTC)