![]() ![]() The output variation is limited by saturation. 4 shows an AC load line with the Q-point moved away from center toward saturation. If the amplifier is driven any further than this, it will “clip” at cutoff, as shown in Fig. V CE can only swing up to its cutoff value and an equal amount below V CEQ. I C can only swing down to near zero and an equal amount above I CQ.The output variation is limited by cutoff in this case. 3 shows an AC load line with the Q-point not centered and moved away from center toward cutoff. This signal is the maximum that can be obtained from the class A amplifier.The peak value of I C equals I CQ, and the peak value of V CE equals V CEQ in this case. V CE can swing from its Q-point value, V CEQ, up to its cutoff value, V ce(cutoff), and down to its saturation value of near zero.I C can vary from its Q-point value, I CQ, up to its saturation value, I c(sat), and down to its cutoff value of zero. This graph shows the AC load line with the Q-point at its center.When the Q-point is at the center of the AC load line, the maximum class A signal can be obtained.įigure 2: Maximum class A output occurs when the Q-point is centered on the AC load line DC and AC load lines intersect at the Q-point.Their size depends on the heat dissipation requirement and the maximum ambient temperature of transistor operation. Heat sinks vary in size, number of fins, and type of material.Heat from the transistor flows through the case to the heat sink and then dissipates in the surrounding air.The case is designed to provide a large contact area between it and an external heat sink. The transistor’s case is always connected to the collector terminal.For BJT power transistors, the collector terminal is the critical junction:.Power devices must dissipate a large amount of internally generated heat. ![]()
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