A system may include a first input for receiving a first signal for driving an amplifier that drives a load, a second input for receiving a second signal driven by the amplifier, and an instability detector for detecting instability of a feedback loop for controlling the first signal based on comparison of the first signal and the second signal.

A system may include a first input for receiving a first signal for driving an amplifier that drives a load, a second input for receiving a second signal driven by the amplifier, and an instability detector for detecting instability of a feedback loop for controlling the first signal based on comparison of the first signal and the second signal.

A system may include a first input for receiving a first signal for driving an amplifier that drives a load, a second input for receiving a second signal driven by the amplifier, and an instability detector for detecting instability of a feedback loop for controlling the first signal based on comparison of the first signal and the second signal.

A system may include a first input for receiving a first signal for driving an amplifier that drives a load, a second input for receiving a second signal driven by the amplifier, and an instability detector for detecting instability of a feedback loop for controlling the first signal based on comparison of the first signal and the second signal.

Described is a frequency selective canceler, which uses signals reflected from a reflective element (e.g. a frequency selective limiter) to selectively reject only signals having a power level above a threshold power level while simultaneously allowing signals having a power level below the threshold power level to pass without rejection.

A frequency selective limiter (FSL) is provided having a transmission line structure with a tapered width. The FSL includes a magnetic material having first and second opposing surfaces. A first conductor is disposed on the first surface of the magnetic material, where a width of the first conductor decreases from a first end of the FSL to a second end of the FSL along a length of the FSL. Two second conductors are disposed on the second surface of the magnetic material, where a width of a gap between the two second conductors decreases from the first end of the FSL to the second end of the FSL along a length of the FSL. The first conductor and two second conductors form a biplanar waveguide transmission line.

A frequency selective limiter (FSL) is provided having a transmission line structure with a tapered width. The FSL includes a magnetic material having first and second opposing surfaces. A first conductor is disposed on the first surface of the magnetic material, where a width of the first conductor decreases from a first end of the FSL to a second end of the FSL along a length of the FSL. Two second conductors are disposed on the second surface of the magnetic material, where a width of a gap between the two second conductors decreases from the first end of the FSL to the second end of the FSL along a length of the FSL. The first conductor and two second conductors form a biplanar waveguide transmission line.

A frequency selective limiter (FSL) is provided having a transmission line structure with a tapered width. The FSL includes a magnetic material having first and second opposing surfaces. A first conductor is disposed on the first surface of the magnetic material, where a width of the first conductor decreases from a first end of the FSL to a second end of the FSL along a length of the FSL. Two second conductors are disposed on the second surface of the magnetic material, where a width of a gap between the two second conductors decreases from the first end of the FSL to the second end of the FSL along a length of the FSL. The first conductor and two second conductors form a biplanar waveguide transmission line.

Described is a frequency selective canceler, which uses signals reflected from a reflective element (e.g. a frequency selective limiter) to selectively reject only signals having a power level above a threshold power level while simultaneously allowing signals having a power level below the threshold power level to pass without rejection.

This radiofrequency power limiter includes at least one transistor, a drain of the transistor being directly connected to a mesh connecting an input to an output of the limiter, a source of the transistor being connected to a common reference potential, and a gate of the transistor being connected to a common control potential. The transistor is not biased between its drain and its source during operation of the limiter.