Many high precision experiments place severe requirements on the noise, linearity and slew rate of flux-locked dc SQUID systems (linearity requirement approaches 1 in 106 for Gravity Probe-B). A computationally efficient and accurate method of simulating a dc SQUID's V-ϕ and I-V characteristics has proven valuable in evaluating and improving various SQUID readout methods. The simulation of the SQUID is based on fitting of previously acquired data from either a real or a modeled device using the Fourier transform of the V-E curve. This method does not predict SQUID behavior, but rather is a way of replicating a known behavior efficiently with portability into various simulation programs such as SPICE. In this paper we discuss the methods used to simulate the SQUID and the flux-locking control electronics and present specific examples of this approach. Results include an estimate of the slew rate and linearity of a simple flux-locked loop using a characterized dc SQUID.
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics