Abstract
We have constructed a two-stage SQUID amplifier, in which
series-mixing local feedback has been used to screen the
SQUID input inductances and hence to boost the power gain
of the amplifier. 2.9 pA/Hz1/2 current noise and 2.9 nH
input inductance of the lower SQUID stage imply energy
resolution of 18 times Planck constant at 4.2 K, which,
arguably, can be further improved by input inductance
screening. The upper stage consists of a 184-series
4-parallel SQUID array, which, when used alone, shows
lower than 0.03 µF 0/Hz1/2 flux noise, but which as a
part of the two-stage amplifier is operated at a higher
flux noise level to provide robust, EMI-tolerant output
signal. The series-mixing feedback also facilitates
negative SQUID input impedance, which would allow
self-oscillating SQUID-based frequency domain
multiplexing
| Original language | English |
|---|---|
| Article number | 042017 |
| Journal | Journal of Physics: Conference Series |
| Volume | 507 |
| Issue number | Part 4 |
| DOIs | |
| Publication status | Published - 2014 |
| MoE publication type | A1 Journal article-refereed |
| Event | 11th European Conference on Applied Superconductivity, EUCAS 2013 - Genoa, Italy Duration: 15 Sep 2013 → 19 Sep 2013 Conference number: 11 |