Variable capacitance devices

A method of fabricating a variable capacitance device, comprising:

• forming a variable resistor including a gate structure disposed over a doped well;
• forming a shielding layer from a conductive material over an upper surface of a semiconductor substrate, the shielding layer being laterally spaced from the gate structure and not overlapping the doped well;
• and
• forming a capacitor in one or more metal layers disposed over the semiconductor substrate and the shielding layer such that the capacitor is coupled in series with the variable resistor, the capacitor comprising
• a first plate comprising
• a first segment extending in a first direction, and
• a first plurality of segments extending from the first segment in a second direction that is perpendicular to the first direction;
• and
• a second plate comprising
• a second segment disposed at a distance from the first segment and extending in the first direction, and
• a second plurality of segments extending from the second segment in the second direction, the second plurality of segments being interdigitated with the first plurality of segments,
• wherein a resistance of the variable resistor is based on a voltage applied to the gate structure disposed over an upper surface of the semiconductor substrate and below the one or more metal layers in which the capacitor is formed such that a resistance of a channel of the variable resistor formed in the semiconductor substrate and a capacitance of the variable capacitance device are adjusted;
• and
• connecting the first plate of the capacitor to the gate structure of the variable resistor.

A variable capacitance device, comprising:

• a plurality of circuit elements arranged in parallel with each other, each of the plurality circuit elements including
• a capacitor having a first capacitance, the capacitor formed in at least one metal layer disposed over a semiconductor substrate and includes
• a first plate comprising
• a first segment extending in a first direction, and
• a first plurality of segments extending from the first segment in a second direction that is perpendicular to the first direction;
• and
• a second plate comprising
• a second segment disposed at a distance from the first segment and extending in the first direction, and
• a second plurality of segments extending from the second segment in the second direction, the second plurality of segments being interdigitated with the first plurality of segments;
• a variable resistor including a gate structure formed over a channel region defined in a doped well formed in the semiconductor substrate;
• at least one interconnect connecting the first plate of the capacitor to the gate structure of the variable resistor;
• and
• a shielding layer formed of a conductive material disposed over an upper surface of the semiconductor substrate and below a lower surface of the at least one metal layer in which the capacitor plates are formed, the shielding layer being laterally spaced from the gate structure and not overlapping the doped well,
• wherein a resistance of the variable resistor is based on a voltage applied to the gate structure, which adjusts a resistance of the channel and a capacitance of the variable capacitance device.