Experimental Demonstration and Performance Estimation of a new Relaxation Oscillator Using a Superconducting Schmitt Trigger Inverter

An experimental demonstration and performance estimation of a superconducting relaxation oscillator using the Schmitt trigger inverter are reported. The superconducting Schmitt trigger inverter is composed of a threshold gate that uses coupled superconducting quantum interference devices. The oscillator is based on the general concept of using the Schmitt trigger inverter and a delayed feedback loop. The oscillation frequency is characterized by the circuit parameters of the delayed feedback loop and the hysteresis structure of the Schmitt trigger. The circuit parameter dependence of the oscillation frequency is estimated by numerical simulations. In order to confirm the circuit operation, the proposed relaxation oscillator is fabricated by a Nb/AlOx/Nb standard process and tested. The operation of the oscillator is demonstrated successfully.