Voltage-controlled oscillator

An apparatus, comprising:

• a first transistor and a second transistor, drains of the first and second transistors electrically coupled to a pair of first output nodes, a gate of the first transistor electrically coupled to the drain of the second transistor, a gate of the second transistor electrically coupled to the drain of the first transistor;
• a third transistor and a fourth transistor, drains of the third and fourth transistors electrically coupled to a pair of second output nodes, a gate of the third transistor electrically coupled to the drain of the fourth transistor, a gate of the fourth transistor electrically coupled to the drain of the third transistor;
• a capacitance unit electrically coupled to at least one pair of the pair of first output nodes and the pair of second output nodes;
• a first inductive unit configured to magnetically couple one of the first output nodes to one of the second output nodes;
• and
• a second inductive unit configured to magnetically couple the other of the first output nodes to the other of the second output nodes.

A method comprising:

• magnetically coupling a first inductive element to a second inductive element;
• magnetically coupling a third inductive element to a fourth inductive element, wherein the first and third inductive elements are electrically coupled to a first cross-coupled transistor pair at a pair of first output nodes, and the second and fourth inductive elements are electrically coupled to a second cross-coupled transistor pair at a pair of second output nodes;
• and
• generating signals having oscillation frequency at the pair of first output nodes and at the pair of second output nodes.