Enhancing the quality factor of planar capacitors without impacting the resonance frequency
The technology described herein is directed towards a planar-type capacitor with a modified design (relative to standard capacitors), in which an array of interconnects facilitates electrical surface current flow between the first conductor and the second conductor, determines the self-resonant frequency of the capacitor, and provides an improved quality factor to an extent. The array (or enlarged area) of conducting interconnects results in capacitors with larger self-resonant frequency, e.g., having a substantially stable capacitance over a range of high radio frequencies, including millimeter wave frequencies. The designs described herein further decouple the capacitor's quality factor from the self-resonant frequency, based on a design modification to the shape of the RF signal port that changes the capacitor's parasitic inductance, facilitating greater flexibility in radio frequency component tuning. The modified capacitor provides benefits in various circuits, e.g., in an impedance or a millimeter wave frequency phase shifter for antenna elements.
1 . A capacitor device, comprising:
a first conductor layer;
a second conductor layer;
a dielectric layer between the first conductor layer and the second conductor layer, the dielectric layer coupled to a physical interconnect overlapping area to facilitate electrical surface current flow between the first conductor layer and the second conductor layer, wherein the physical interconnect overlapping area is configured to determine a resonance frequency of the capacitor device; and
a radio frequency port section comprising an angled conductor configured to couple radio frequency signals to the capacitor device, wherein the angled conductor determines a quality factor value of the capacitor device that is substantially independent of at least one of:
the resonance frequency of the capacitor device, or
a capacitance value of the capacitor device, wherein the physical interconnect overlapping area is substantially centered substantially opposite the radio frequency port section.
2 . The capacitor device of claim 1 , wherein the angled conductor comprises a tapered shape that narrows a width of the angled conductor in a direction pointing towards the physical interconnect overlapping area.
3 . The capacitor device of claim 1 , wherein the angled conductor comprises a first angled side and a second angled side, the angled conductor comprising a tapered shape that narrows a first width of the first angled side in a direction pointing towards the physical interconnect overlapping area, and narrows a second width of the second angled side in the direction pointing towards the physical interconnect overlapping area.
4 . The capacitor device of claim 1 , wherein one side of the angled conductor comprises a first angled part and a second angled part, wherein the first angled part narrows a first width of the first angled part for a first length of the first angled part, and wherein the second angled part widens a second width of the second angled part for a second length of the second angled part.
5 . The capacitor device of claim 1 , wherein a first side of the angled conductor comprises a first angled part and a second angled part, wherein the first angled part narrows a first width of the first angled part for a first length of the first angled part, wherein the second angled part widens a second width of the second angled part for a second length of the second angled part, wherein a second side of the angled conductor comprises a third angled part and a fourth angled part, wherein the third angled part narrows a third width of the third angled part for a third length of the third angled part, and wherein the fourth angled part widens a fourth width of the fourth angled part for a fourth length of the fourth angled part.
6 . The capacitor device of claim 1 , wherein the physical interconnect overlapping area comprises a group of respective conducting interconnects as respective vias that determine an overall size of the physical interconnect overlapping area.
7 . The capacitor device of claim 6 , wherein the respective conducting interconnects are distributed in a circular or substantially circular pattern.
8 . The capacitor device of claim 6 , wherein the respective conducting interconnects are distributed proximate to a periphery of the first conductor layer.
9 . The capacitor device of claim 1 , wherein the physical interconnect overlapping area is positioned proximate to a periphery of a radio frequency ground plane of the capacitor device.
10 . A device, comprising:
a first conductor electrode separated from a second conductor electrode by a dielectric medium to operate as a metal-insulator-metal capacitor with a radio frequency ground plane;
a physical interconnect overlapping area aligned with a periphery of the radio frequency ground plane to facilitate electrical surface current flow between the first conductor and the second conductor to reduce a surface current density of the metal-insulator-metal capacitor, wherein a resonance frequency of the device is based on a size of the physical interconnect overlapping area; and
a radio frequency port section comprising an angled conductor configured to couple radio frequency signals to the device, wherein a shape of the angled conductor determines an enhanced device quality factor relative to a non-angled conductor, and wherein the device quality factor is substantially independent of at least one of:
the resonance frequency of the device, or
a capacitance value of the device, wherein the physical interconnect overlapping area is substantially centered substantially opposite the radio frequency port section.
11 . The device of claim 10 , wherein the angled conductor comprises at least one angled side that narrows a width of the angled conductor in a direction pointing towards the physical interconnect overlapping area.
12 . The device of claim 10 , wherein the angled conductor comprises at least one multiangled side that varies a width of the angled conductor in a direction pointing towards the physical interconnect overlapping area.
13 . The device of claim 10 , wherein the physical interconnect overlapping area comprises a geometrically distributed array of interconnects that enables electrical vias from the first conductor electrode to the second conductor electrode through the dielectric medium.
14 . The device of claim 10 , wherein the dielectric medium is a first dielectric medium, and further comprising a third conductor electrode separated from the second conductor electrode by a second dielectric medium.
15 . The device of claim 10 , wherein the physical interconnect overlapping area comprises a group of respective conducting interconnects as respective vias that determine an overall size of the physical interconnect overlapping area, and wherein the respective conducting interconnects are distributed in a circular or substantially circular pattern.
16 . A capacitor, comprising:
a first conductor overlapping with a dielectric layer coupled to a physical interconnect overlapping area overlapping with a second conductor that is coupled to a substrate, the first conductor electrically coupled to the second conductor via an array of interconnects through the dielectric layer comprised in the physical interconnect overlapping area, wherein the array of interconnects facilitates electrical surface current flow between the first conductor and the second conductor, and determines a self-resonant frequency of the capacitor; and
a radio frequency port section comprising a tapered conductor configured to couple radio frequency signals to the capacitor, wherein the tapered conductor determines a quality factor value of the capacitor that is substantially independent of at least one of:
the self-resonant frequency of the capacitor, or
a capacitance value of the device, wherein the physical interconnect overlapping area is substantially centered substantially opposite the radio frequency port section.
17 . The capacitor of claim 16 , wherein the angled conductor comprises at least one angled or curved side that narrows a width of the angled conductor in a direction pointing towards a center of the capacitor.
18 . The capacitor of claim 16 , wherein the array of interconnects comprises a geometrically distributed array positioned proximate to a periphery of the first conductor.
19 . The capacitor of claim 16 , wherein the capacitor is deployed as a tuning element as part of an impedance matching network.
20 . The capacitor of claim 16 , wherein the capacitor is a part of a millimeter-wave frequency phase shifter for antenna elements.