A Low Noise, Low Power, Cryogenic Differential Amplifier for Reducing the Timing Jitter in Superconducting Nanowire Single Photon Detectors

Long range optical communications using Superconducting Nanowire Single Photon Detectors (SNSPDs) is a new and promising technology for deep spacecraft communications. SNSPDs are planned for use in future NASA space-to-ground laser communication. In the current state of the art, the clock rates are limited in part by the timing jitter of the SNSPD. Improving the timing jitter of SNSPDs results in higher clock rates, higher data rates and longer ranges. Currently timing jitters of 2.7pS have been demonstrated in laboratory research. The Phase 1 SBIR Project focused on the feasibility of a low power, low noise cryogenic differential amplifier. It is expected that integrating the amplifier with the SNSPD will lower the timing jitter to less than 1pS, allowingnbsp;higher data rates and longer ranges without requiring additional mass and power on a spacecraft. Higher data rates will also result in higher resolution images received from space probes. The successful completion of Phase 1 resulted in the delivery of a differential amplifier prototype for integration and testing with a SNSPD. The delivered amplifier exhibits 20db of gain, 5K noise temperature with 2.0mW of power dissipation. The next phase towards a long-range communication system is to fabricate a multi-channel MMIC and construct a 64channel receiver. A 64 channel receive allows 64 digital bits of information. The large number of digital bits are necessary for high speed communications and high-resolution images. The scope of the Phase 2 research will focus on miniaturization of the differential amplifier and design of the 64channel receiver.nbsp; Delivery of the receiver will push the efforts for a longer-range optical communications system.nbsp;