Structure for circuit interconnects
Described are various configurations of high-speed via structures. Various embodiments can reduce or entirely eliminate insertion loss in high-speed signal processing environments by using impedance compensation structures that decrease a mismatch in components of a circuit. An impedance compensation structure can include a metallic structure placed near a via to lower an impedance difference between the via and a conductive pathway connected to the via.
1. A circuit comprising:
a conductive contact disposed on a top side of a circuit board structure comprising one or more layers of a circuit board;
a conductive path disposed on an opposed bottom side of the circuit board structure;
a via structure extending through the one or more layers of the circuit board, the via structure interconnecting the conductive contact and the conductive path; and
a group of metallic structures embedded in the circuit board directly beneath a bottom end of the via structure and separated from the bottom end of the via structure by a dielectric material, the group of metallic structures and the conductive path having a same width to decrease an impedance difference between the via structure and the conductive path;
wherein the group of metallic structures and a portion of the conductive path that is connected to the via structure have a same perpendicular width that is perpendicular to the conductive path; and
wherein the group of metallic structures further has a parallel width that is the same as the perpendicular width, the parallel width being a width of the group of metallic structures that is parallel to the conductive path.
2. The circuit of claim 1 , wherein each metallic structure in the group is separate from other metallic structures of the group.
3. The circuit of claim 1 , wherein the circuit board includes a first layer, a second layer and a ground layer disposed between the first layer and the second layer, wherein the top side of the circuit board structure is a surface of the first layer of the circuit board and the opposed bottom side of the circuit board structure is another surface of the second layer of the circuit board.
4. The circuit of claim 3 , wherein the via structure extends through the first layer and the ground layer of the circuit board, and partially extends through a portion of the second layer.
5. The circuit of claim 1 , wherein the group of metallic structures are embedded in dielectric material of the circuit board.
6. The circuit of claim 5 , wherein the circuit is a multilayer circuit in which the conductive path is a trace surrounded by dielectric material.
7. The circuit of claim 1 , wherein each metallic structure is a metallic square pad.
8. The circuit of claim 7 , wherein the group of metallic structures form a square group of metallic pads.
9. The circuit of claim 8 , wherein the square group of metallic pads are axially aligned with the via structure.
10. The circuit of claim 1 , wherein the group of metallic structures decrease the impedance difference by lowering an impedance of the via structure and the conductive contact.
11. The circuit of claim 1 , wherein the conductive contact is a terminal that connects to an external circuit.
12. The circuit of claim 11 , wherein the circuit is transceiver circuit, and the external circuit is a photonic integrated circuit (PIC) that generates high frequency modulated signal.
13. The circuit of claim 12 , wherein the high frequency modulated signal is Pulse Amplitude Modulation (PAM) signal.
14. The circuit of claim 13 , wherein the high frequency modulated signal is four level PAM signal.
15. A structure for circuit interconnects, comprising:
a first grounding plane;
a second grounding plane beneath the first grounding plane;
a substrate layer of dielectric material between the first grounding plane and the second grounding plane;
a trace embedded in the substrate layer;
a pillar above the first grounding plane;
a via structure extending through the first grounding plane, the via structure comprising a first end portion connected to the pillar and a second end portion connected to the trace; and
a group of metallic structures embedded in the substrate layer directly beneath the second end portion of the via structure and separated from the second end portion of the via structure by the dielectric material, the group of metallic structures and the trace having a same width to decrease an impedance difference between the via structure and the trace;
wherein the group of metallic structures and a portion of the trace that is connected to the via structure have a same perpendicular width that is perpendicular to the trace; and
wherein the group of metallic structures further has a parallel width that is the same as the perpendicular width, the parallel width being a width of the group of metallic structures that is parallel to the trace.