Transmission line with integrated connection pads for circuit elements
View Patent ↗An optoelectronic assembly includes a circuit board having a set of signal traces, where one or more of the signal traces has a junction point that integrates a pad of a circuit element. Exemplary circuit elements include a resistor, capacitor, and an inductor. The junction point has a first width and a first thickness, and the one or more signal traces have a second width and a second thickness. The dimensions of the junction point and the dimensions of the one or more signal traces are configured such that the first width and the second width are substantially similar, and that the first thickness and the second thickness are substantially similar. In one embodiment, the first width is no greater than 125% of the second width.
1. An optoelectronic assembly including:
a circuit board with a plurality of signal traces, one or more of the signal traces having a junction point that integrates a pad of a circuit element;
the junction point having dimensions including a first width and a first thickness; and the one or more signal traces having dimensions including a second width and a second thickness;
wherein the dimensions of the junction point and the dimensions of the one or more signal traces are configured such that the first width and the second width are substantially similar, and that the first thickness and the second thickness are substantially similar and such that parasitic inductance created at the junction point is substantially offset by parasitic capacitance created at the junction point.
2. The optoelectronic assembly of claim 1 , wherein the first thickness of the pad at the junction point is the same as the second thickness of the one or more signal traces.
3. An optoelectronic assembly, comprising:
an optoelectronic component;
a circuit board including a circuit coupled to the optoelectronic component by a plurality of signal traces, each signal trace of the plurality of signal traces comprising a high frequency transmission line; and
a first biasing circuit coupled to a first signal trace of the plurality of signal traces at a first junction point, the first junction point incorporating a region of the first signal trace and a first pad of the first biasing circuit;
wherein the first signal trace has a first width, and the first junction point has a second width that is selected such that a parasitic inductance created at the first junction point is substantially offset by parasitic capacitance created at the first junction point.
4. The optoelectronic assembly of claim 3 , wherein the first-width is approximately equal to 17 mils, and the second width is approximately equal to 20 mils.
5. The optoelectronic assembly of claim 3 , wherein the first signal trace also has a first thickness, and the first junction point has a second thickness, and wherein the first thickness is substantially similar to the second thickness.
6. The optoelectronic assembly of claim 5 , wherein the second thickness of the first junction point is substantially the same as the first thickness of the first signal trace.
7. The optoelectronic assembly of claim 5 , further including a second biasing circuit coupled to a second signal trace of the plurality of signal traces at a second junction point, the second junction point incorporating a region of the second signal trace and a second pad of the second biasing circuit, the second signal trace having a third width that is substantially similar to the first width of the first signal trace and to the second width of the first junction point.
8. The optoelectronic assembly of claim 7 , wherein the second signal trace has a third thickness that is substantially similar to the first thickness of the first signal trace and to the second thickness of the first junction point.
9. The optoelectronic assembly of claim 7 , wherein the second biasing circuit comprises an RLC circuit.
10. The optoelectronic assembly of claim 5 , wherein the first biasing circuit is coupled to the first signal trace at a second junction point, in addition to the first junction point, the second junction point incorporating a second region of the first signal trace and a second pad of the first biasing circuit, the second junction point having a third width that is substantially similar to the first width of the first signal trace and the second width of the first junction point.
11. The optoelectronic assembly of claim 10 , wherein the second signal trace has a third thickness that is substantially similar to the first thickness of the first signal trace and to the second thickness of the first junction point.
12. The optoelectronic assembly of claim 10 , wherein the first biasing circuit includes a first resistor coupled to the first pad and a first inductor coupled to the second pad.
13. The optoelectronic assembly of claim 12 , wherein the first biasing circuit further includes a second resistor coupled to the first resistor and a first capacitor coupled to the first inductor.
14. The optoelectronic assembly of claim 3 , wherein the second width is greater than the first width but not greater than 125% of the first width.
15. The optoelectronic assembly of claim 3 , wherein the first biasing circuit comprises an RLC circuit.
16. The optoelectronic assembly of claim 15 , wherein the first biasing circuit has at least one resistor having a resistance of 5 to 50 ohms, at least one inductor having an inductance of 2 to 12 nanoHenries, and at least one capacitor having a capacitance of 0.1 to 10 picoFarads.
17. The optoelectronic assembly of claim 3 , wherein the first biasing circuit further comprises a biasing circuit for a laser diode, the biasing circuit configured to minimize the voltage drop across the biasing circuit, and to provide a biasing current to the laser diode without interfering with high frequency current transmitted through the first signal trace.