Digitally controlled oscillator for a millimeter wave semiconductor device

A capacitor unit, comprising:

• a first NFET having a gate and a back gate connected to a control signal, and a drain connected to a first voltage source;
• a second NFET having a gate connected to ground, a back gate connected to the control signal, and a drain connected to the source of the first NFET;
• and
• a third NFET having a gate and a back gate connected to the control signal, a drain connected to the source of the second NFET, and a source connected to a second voltage source.

A method, comprising:

• providing a digitally controlled oscillator (DCO) comprising a transformer, the transformer comprising a primary winding and a secondary winding, the secondary winding comprising a first port, a second port, and an array of capacitor units, wherein each capacitor unit comprises a first NFET having a gate and a back gate connected to a control signal, and a drain connected to the first port of the secondary winding;
• a second NFET having a gate connected to ground, a back gate connected to the control signal, and a drain connected to the source of the first NFET;
• and a third NFET having a gate and a back gate connected to the control signal, a drain connected to the source of the second NFET, and a source connected to the second port of the secondary winding;
• increasing the frequency of the DCO by a fine tuning resolution by switching on one capacitor unit;
• and
• decreasing the frequency of the DCO by the fine tuning resolution by switching off one capacitor unit.