Oscillator circuit and device

An oscillator comprising:

• a forward stage comprising an NMOS transistor coupled between first through third terminals, wherein the second terminal is coupled to a first voltage node;
• and
• a transformer-coupled band-pass filter (BPF) coupled between the first and third terminals, the transformer-coupled BPF comprising:
• a capacitive device coupled between the first and third terminals;
• and
• a transformer in a metal layer of an integrated circuit (IC), the transformer comprising:
• a first winding comprising a first conductive structure coupled to one of the first or third terminals, and a second conductive structure coupled to a second voltage node;
• a third conductive structure comprising a first extending portion connected to the first conductive structure, and a second extending portion connected to the second conductive structure;
• and
• a second winding comprising a fourth conductive structure comprising a third extending portion coupled to the second voltage node, and a fourth extending portion coupled to the other of the first or third terminals, wherein
• the third extending portion is between the second conductive structure and the first extending portion, and
• the fourth extending portion is between the first conductive structure and the second extending portion.

An oscillator comprising:

• a forward stage comprising first through third terminals, wherein the second terminal is coupled to a first voltage node;
• and
• a transformer-coupled band-pass filter (BPF) coupled between the first and third terminals, the transformer-coupled BPF comprising:
• a capacitive device coupled between the first and third terminals;
• and
• a transformer in a metal layer of an integrated circuit (IC), the transformer comprising:
• a first winding comprising a first conductive structure coupled to one of the first or third terminals, and a second conductive structure coupled to a ground node;
• a third conductive structure comprising a first extending portion connected to the first conductive structure, and a second extending portion connected to the second conductive structure;
• and
• a second winding comprising a fourth conductive structure comprising a third extending portion coupled to the ground node, and a fourth extending portion coupled to the other of the first or third terminals, wherein
• the third extending portion is between the second conductive structure and the first extending portion,
• the fourth extending portion is between the first conductive structure and the second extending portion, and
• the first or second winding further comprises a tap coupled to a second voltage node.