VERTICAL BALLAST TECHNOLOGY FOR POWER HBT DEVICE

摘要

Power amplification devices are disclosed having a vertical ballast configuration to prevent thermal runaway in at least one stack of bipolar transistors formed on a semiconductor substrate. To provide a negative feedback to prevent thermal runaway in the bipolar transistors, a conductive layer is formed over and coupled to the stack. A resistivity of the conductive layer provides an effective resistance that prevents thermal runaway in the bipolar transistors. The vertical placement of the conductive layer allows for vertical heat dissipation and thus provides ballasting without concentrating heat.