AB039

To achieve reliable power amplifier designs you must con-sider the stress on the amplifier compared to its power handling limitations. Power handling limits are specified by the Safe Operating Area (SOA) curves of the power amp. Stress on the amplifier depends on amplifier load and signal conditions which can be evaluated with straightforward techniques.Consider the simplified power op amp shown in Figure 1.and Q₁  provide positive and negative Output transistors Q₂is shown flowing out of the output current to the load. I_OUT is supplying the output current. For positive amplifier, so Q₁is "off"and can be ignore output current, Q₂ under load is related to the output current.

The stress on Q₁ (its collector-to-emitter voltage, and the voltage across Q₁). The product of these quantities, I V_OUT , is the powerV_CE   V_CE. This power dissipation is one important dissipation of Q₁ consideration, but the safe operating area provides a mo complete description of the amplifie's limits.