Flux flow amplifiers and logic operating at millimeter wave frequencies

Summary form only given. Superconducting flux flow transistors (SFFTs) have recently been used in a W-band amplifier operating from 91 to 98 GHz and in an invertor configured as an oscillator operating at 86 GHz. These SFFTs consist of three weakened YBaCuO links in parallel. The links are about 1-μm wide, 3-μm long, and 20-nm thick (relative to an electrode thickness of about 200 nm). The links are biased above their local critical field so that vortices flow through the links in accordance with the Lorentz-type force supplied by the bias. The `gate´ is a control line located proximate to the link system and supplies a local magnetic field. Above a critical current, flux flow begins and the device enters the active region characterized by a transresistive response to control current and a finite output resistance. A flux flow invertor circuit can consist of 2 SFFTs: both devices are in parallel with the current bias and the input is a control current to one device