Series resonance drive circuit for magnetic bubble memory

A series resonance drive circuit for a magnetic bubble memory, comprising:

• (a) a magnetic bubble memory chip in which magnetic bubbles are driven in accordance with a rotating magnetic field,
• (b) X and Y coils arranged orthogonally to each other to generate the rotating magnetic field in a plane of said magnetic bubble memory chip,
• (c) resonance capacitors each connected in series with respective one of said X and Y coils to form a series resonance circuit with the respective one of said X and Y coils at a frequency of said rotating magnetic field,
• (d) power supplies each connected to the respective one of said series resonance circuits to supply a cyclic wave current consisting of only an A.C. component to the respective one of said series resonance circuits, and
• (e) reactance means electrically connected to said series resonance circuits and for compensating a mutual inductance and a capacitance due to inductive and capacitive couplings between said X and Y coils, said reactance means including a variable inductor having one terminal connected in series with said X ayd Y coils, respectively and the other terminal grounded and a capacitor electrically connected between said series resonance circuits.