A miniature tunnel diode oscillator for condensed matter physics experiments

We have developed a new design for a small tunnel diode oscillator circuit, which minimizes eddy current pickup in changing magnetic fields, minimizes parasitic reactance for achieving high frequency operation, and is small enough to fit in the confined spaces that are common in high magnetic field dilution refrigerator environments. The new design has been tested up to 1.5 GHz and at temperatures from room temperature down to 25 mK. We have also used the system to take measurements up to 60 T in a pulsed magnetic field. In this manuscript, we analyze the circuit and give guidance for using the circuits and the limits of operation.