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 device for comparing the peak value of a periodic voltage signal or a linear combination of periodic voltage signals with a reference voltage includes a reference transconductor element for converting the reference voltage into a reference current, respective transconductor elements for converting each of the periodic voltage signals into respective periodic current signals, a current-comparison node for comparing the respective periodic current signals with the reference current, generating a comparison current as a difference between the sum of the aforesaid periodic current signals and the reference current, a current rectifier supplied with the comparison current, a hold capacitor charged with the output current of the current rectifier, and a discharge-current generator in parallel to the hold capacitor.

Abstract: A device for detecting the peak value of a signal with crest factor not known a priori includes a pair of peak detectors, each of which includes a rectifier element and a discharge-current generator and generates a respective output signal that is a function of the ratio between a physical dimension of the rectifier element and the intensity of discharge current produced by the generator. The ratio is different for the two detectors, and a combination network combines the output signals of the two peak detectors with one another and produces a combined signal indicating the peak value sought with high accuracy.

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.