Hybrid superconducting-magnetic fault current limiter

This limiter is intended to protect high-speed electronic circuits from subnanosecond duration high voltage transients. It operates at liquid nitrogen temperature and could be used in cryogenic electronic systems based on high-T/sub c/ superconducting devices. The device operates because of electric current induced switching from the superconducting state to the normal state and electric field induced resistance changes in manganite. The attenuation in high-speed transmission lines occurs, when, as the result of the action of a current pulse, the resistance of the superconducting Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ strip, connected in series with the transmission line, increases, while the resistance of the manganite La/sub 0.67/Ca/sub 0.33/MnO/sub 3/ film, connected in parallel to this line, decreases. The attenuation achieved by such limiters exceeds 20-30 dB. In its non-attenuating regime, the bandwidth of the device could be up to 18 GHz.