Simulator Experiments on Josephson Junction Harmonic Mixers

We have studied the JJ harmonic mixing with an analog simulator devised by Magerlein. For even-harmonic mixing, there are two operation modes: zero-bias operation and finite-bias operation. The former is peculiar to even-harmonic mixing, while the latter is common to both even- and odd-harmonic mixing. Zero-bias operation is possible with a supply of LO current that suppresses the zero-voltage step completely, and it has the advantage of eliminating the dc bias supply and its accompanying heating effect and shot noise. For relatively low LO frequency (≃0.6), zero-bias operation has a higher conversion efficiency than does finite-bias operation. 2nd harmonic mixing under zero-bias operation has a conversion efficiency nearly equal to the fundamental mixing in the range 0.5.