Abstract: A protection method may prevent a load-mismatch-induced failure in solid-state power amplifiers. In an RF power amplifier, the load voltage standing-wave ratio results in very high voltage peaks at the collector of the final stage and may eventually lead to permanent failure of the power transistor due to avalanche breakdown. The method avoids breakdown by attenuating the input power to the final stage during overvoltage conditions, thus limiting the output collector swing. This is accomplished by a feedback control system, which detects the peak voltage at the output collector node and clamps its value to a given threshold by varying the circuit gain. Indeed, the control loop is unlocked in the nominal condition and it acts when an output mismatching condition is detected. A control circuit also allows a supply-independent collector-clamping threshold to be accurately set.

Abstract: A gain stage control method may include providing a control current signal; generating a regulation current signal connected to the control current signal; transforming the regulation current signal into a biasing current, proportional to the regulation current signal; and biasing the gain stage by using the biasing current. The biasing current may be related to the control current signal by an exponential law.

Abstract: A protection method may prevent a load-mismatch-induced failure in solid-state power amplifiers. In an RF power amplifier, the load voltage standing-wave ratio results in very high voltage peaks at the collector of the final stage and may eventually lead to permanent failure of the power transistor due to avalanche breakdown. The method avoids breakdown by attenuating the input power to the final stage during overvoltage conditions, thus limiting the output collector swing. This is accomplished by a feedback control system, which detects the peak voltage at the output collector node and clamps its value to a given threshold by varying the circuit gain. Indeed, the control loop is unlocked in the nominal condition and it acts when an output mismatching condition is detected. A control circuit also allows a supply-independent collector-clamping threshold to be accurately set.

Abstract: A gain stage control method may include providing a control current signal; generating a regulation current signal connected to the control current signal; transforming the regulation current signal into a biasing current, proportional to the regulation current signal; and biasing the gain stage by using the biasing current. The biasing current may be related to the control current signal by an exponential law.