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Forn-Díaz, P. (author), Schouten, R.N. (author), Den Braver, W.A. (author), Mooij, J.E. (author), Harmans, C.J.P.M. (author)We fabricated and tested a squelch circuit consisting of a copper powder filter with an embedded Josephson junction connected to ground. For small signals (squelch ON), the small junction inductance attenuates strongly from dc to at least 1 GHz, while for higher frequencies dissipation in the copper powder increases the attenuation exponentially...journal article 2009
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Vink, I.T. (author), Nooitgedagt, T. (author), Schouten, R.N. (author), Vandersypen, L.M.K. (author), Wegscheider, W. (author)The authors employ a cryogenic high electron mobility transistor (HEMT) amplifier to increase the bandwidth of a charge detection setup with a quantum point contact (QPC) charge sensor. The HEMT is operating at 1?K and the circuit has a bandwidth of 1?MHz. The noise contribution of the HEMT at high frequencies is only a few times higher than...journal article 2007