Submount, pedestal, and bond wire assembly for a transistor outline package with reduced bond wire inductance
View Patent ↗The present invention relates generally to optoelectronic devices, and particularly to a submount, pedestal, and bond wire assembly for a transistor outline package. A bottom surface of the submount is connected to a top surface of the pedestal. Each bond wire in a bond wire set is connected to a position on the top surface of the submount, and to a position on the signal line. The signal line is positioned a first distance from the position on the top surface of the submount and a second distance from the pedestal. The submount is sized such that a portion of the bottom and the top surface of the submount extends beyond the top surface of the pedestal such that the first distance is less than the second distance.
1. An optoelectronic assembly including:
a submount, a pedestal, a plurality of bond wires providing a bond wire set, and a signal line;
a bottom surface of the submount connected to a top surface of the pedestal; each bond wire in the bond wire set connected to a position on a top surface of the submount, and to a position on the signal line, said top surface being a surface opposite to the bottom surface of the submount;
the signal line positioned a first distance from the position on the top surface of the submount and a second distance from the pedestal;
wherein the submount is sized such that a portion of the bottom and the top surface of the submount extends beyond the top surface of the pedestal such that the first distance is less than the second distance, and wherein a plurality of the bond wires in the bond wire set contact a portion of the sub mount that overhangs and extends beyond the top surface of the pedestal, thereby reducing inductive effects of the bond wires.
2. The optoelectronic assembly of claim 1 , wherein the submount contains no capacitors and inductors.
3. The optoelectronic assembly of claim 1 , wherein the bottom surface of the submount further includes a ground plane, and the top surface of the submount further includes one or more signal traces.
4. The optoelectronic assembly of claim 3 , wherein the submount, the one or more signal traces of the submount, and the ground plane of the submount function as a transmission line, reducing inductive effects of the bond wire set.
5. The optoelectronic assembly of claim 4 , wherein the one or more signal traces of the submount are configured so that an impedance of the signal traces approximately matches an impedance of the signal line.
6. The optoelectronic assembly of claim 3 , wherein the ground plane of the submount does not extend substantially beyond a width of the top surface of the pedestal, so as to not interfere with transmission characteristics of the signal line.
7. The optoelectronic assembly of claim 1 , wherein the top surface of the submount further includes one or more signal traces, and wherein the pedestal acts as a ground plane to the one or more signal traces of the top surface of the submount.
8. The optoelectronic assembly of claim 1 , further comprising at least one of a capacItor and an inductor incorporated into the submount to compensate for impedance presented by the bond wire set.
9. The optoelectronic assembly of claim 1 , wherein the submount is substantially comprised of one or more of: aluminum nitride and alumina ceramic.
10. An optoelectronic assembly comprising:
a laser pedestal having a top, a bottom, and one or more partially concentric sides;
a laser submount adjacent to the top of the laser pedestal and having a plurality of edges, the edges of the laser submount overhanging and extending beyond the top of the laser pedestal, the laser submount for mounting a laser diode thereupon;
a plurality of data signal contacts, the data signal contacts extending proximate the one or more partially concentric sides of the laser pedestal, the data signal contacts operating as a coaxial cable with respect to the partially concentric sides of the laser pedestal;
wherein the laser submount is closer to the data signal contacts than are the partially concentric sides of the laser pedestal, because the submount overhangs and extends beyond the pedestal;
a plurality of short bond wires, the bond wires connecting the plurality of data signal contacts to portions of the laser submount that overhang and extend beyond the pedestal, thereby reducing inductive effects in a transmission system including the data signal contacts, the laser submount, the short bond wires, and a laser diode.
11. The optoelectronic assembly of claim 10 , wherein the plurality of data signal contacts comprises two data signal contacts that form a differential data signal connection.
12. The optoelectronic assembly of claim 10 , wherein the submount further comprises a top surface and a bottom surface, and wherein the bottom surface of the submount further includes a ground plane, and the top surface of the submount further includes one or more signal traces.
13. The optoelectronic assembly of claim 12 , wherein the submount, the one or more signal traces of the submount, and the ground plane of the submount function as a transmission line, reducing inductive effects of the plurality of short bond wires.
14. The optoelectronic assembly of claim 12 , wherein the one or more signal traces of the submount are configured so that an impedance of the signal traces approximately matches an impedance of the data signal contacts.
15. The optoelectronic assembly of claim 12 , wherein the ground plane of the submount does not extend substantially beyond a width of the top surface of the pedestal, so as to not interfere with transmission characteristics of the plurality of data signal contacts.