Low Noise SQUID Array Amplifiers for High Speed Applications

A low-noise amplifier chip, based on Superconducting QUantum Interference Device (SQUID) technology, is needed for the high speed instrumentation used in nuclear physics experiments. SQUIDs are ultra-high-speed devices that are extremely sensitive detectors of magnetic flux. They dissipate very low power and, as a result, can be instrumented with detectors in situations where low power dissipation and high speed are critical. In previous work, an analog SQUID array amplifier system ¿ which has room temperature electronics, sensitivity better than 2 pA/root Hz, and a bandwidth in excess of 10 MHz ¿ has been developed. To improve upon the bandwidth, this project will develop a novel, SQUID amplifier architecture that utilizes an analog SQUID coupled to an array of SQUIDs using Josephson Transmission Lines (JTLs). Because bandwidth associated with JTLs is on the order of several GHz, this SQUID array amplifier can achieve a switching speed in excess of 50 psec. In Phase I, a SQUID array amplifier with 1 GHz bandwidth will be designed, developed, and demonstrated. Single amplifier chips, which contain arrays of SQUID amplifiers for integration in a multi-channel systems, will be designed and fabricated. The amplifier chips will be compact and cost effective, and will require minimal support electronics. Commercial Applications And Other Benefits as described by the Applicant: A low noise high speed SQUID amplifier chip would find use in many high-speed digital systems, such as analog-to-digital converters (ADCs) and digital receivers. Such a SQUID, coupled to a large transformer (100 nH), would enable the development of an amplifier with sub-pico ampere sensitivity, needed for many applications. A sensitive, low-speed version of these SQUID chips should have commercial applications in non-invasive medical diagnostic instrumentation or as SQUID amplifiers for readout of cryogenic detector arrays.