Project Title:

Two Stage DC SQUID Amplifiers for Cryogenic Sensors

HYPRES,Inc.
175 Clearbrook Road
Elmsford, NY 10523

93-1		08.14	1190			Amount Requested $69,683.00

Two Stage DC SQUID Amplifiers for Cryogenic Sensors

Abstract:

Superconducting Quantum Interference Devices (SQUIDs) are extremely 
sensitive detectors of magnetic flux and can be used as low noise 
amplifiers for many applications such as cryogenic detectors and 
biomagnetic measurements.  In order to utilize a SQUID as an 
amplifier, extensive peripheral electronics are required.  Such 
room temperature electronics are very expensive, specially for 
space-qualified applications, and are responsible for a substantial 
portion of the cost of the commercial magnetometer systems.  
Therefore, it is highly advantageous to simplify the electronics 
required to operate SQUIDs.  This project will lead to the 
development of an all thin-film SQUID array amplifier chip.  The 
proposed DC SQUID amplifier integrates several (on the order of a 
hundred) DC SQUID gates with a high sensitivity analog SQUID 
magnetometer.  Each chip, in addition to having a SQUID array 
coupled to an analog SQUID, will also have an integrated 
superconducting transformer to facilitate its interface to an 
external pick up coil.  This scheme will eliminate the need for the 
most critical part of the peripheral electronics, that is, the low 
noise amplifiers, which, in practical systems, determines the noise 
floor of the systems.  Such a system will be compact and cost 
effective, and requires ordinary support electronics.  As a result 
of this effort, it will be possible to design and fabricate SQUID 
chips that will contain arrays of such SQUIDs for integration in 
magnetometer systems, thereby reducing the complexity of the room 
temperature electronics for such systems.  Due to significant 
progress in superconducting electronics at HYPRES in recent months, 
we are actually proposing to design, fabricate and evaluate these 
SQUID array amplifier chips under this phase I program.  The goal 
for the flux noise for such chips is less than 5XlO-6~o/~Hz when 
operated from 4.2 K down to milliKelvins.

This project will lead to the development of an all-thin film SQUID 
chip where the chip has a self-contained low noise analog SQUID 
amplifier with on-chip SQUID arrays as amplifiers.  This chip will 
require ordinary support electronics and consequently systems 
containing a few such chips can be realized very cost effectively 
for integration in SQUID magnetometer systems.

SQUID magnetometer, Low noise amplifier, Non-destructive evaluation