Superconductor SQIF Amplifier for Wideband SIGINT Receivers

The detection and identification of very low-level electromagnetic waveforms for Signal Intelligence (SIGINT) relies on receiver systems with very low noise figure and high dynamic range. This task becomes even more challenging when the signal sources of interest are wideband and/or when they rely on spread-spectrum, frequency-hopping or other digital signal-processing techniques for signal security. We propose to develop the Superconducting Quantum Interference Filter (SQIF) into a wideband ultra-linear low-noise amplifier to intercept and help identify these signals. The operation of Niobium SQIF amplifiers at a temperature of 4 Kelvin inherently enables very low noise temperatures. The SQIF amplifier is expected to dissipate only microwatts of power, enabling relatively low-power cryocoolers to be used. New designs and techniques are required to develop the spur-free dynamic range and wide bandwidth that will make them useful to near-future SIGINT receivers. BENEFIT: This development, if successful, will enable the detection and identification of low-probability-of-intercept and other small signals of interest that would otherwise be unable to detect. Our amplifier will have very low noise, a target bandwidth of DC to greater than 18 GHz, and a large spur-free dynamic range. This technology can be used for other applications, such as deep-space communications for unmanned NASA vehicles, wireless communications. The amplifier itself will consume only microwatts of power, which is orders of magnitude less than semiconductor amplifiers. In addition, it is compatible with Niobium superconductor mixed-signal and other superconductor digital circuits, which can be operated with low power dissipation on the same 4-Kelvin platform.