Abstract
A linear amplifier using a flux-flow phenomenon in a long Josephson junction has been designed and tested by connecting a load resistance. The present experiment has demonstrated that a current gain of 500/Ws (1/µm) is obtained for the load resistance of 9 mΩ when an input signal is applied with a control line of width Ws (µm). An equivalent circuit of the amplifier has also been presented, which shows that the device is most suitable for current amplification with large gain in low impedance circuits.