A load testing circuit a circuit tests the load impedance of a load connected to an amplifier. The load impedance includes a first terminal and a second terminal, the load testing circuit comprising a signal generator providing a test signal of a defined bandwidth to the first terminal of the load impedance, an energy-storing element being connected to the second terminal of the load impedance and providing an output signal, and a measuring unit that measures the output signal or compares the output signal with a reference.