Circuit interconnect for optoelectronic device for controlled impedance at high frequencies
View Patent ↗An optoelectronic assembly includes a transistor outline (TO) package that houses an optoelectronic device. The TO package and the optoelectronic device are coupled to a circuit interconnect. The circuit interconnect includes an insulator having a first side for transmitting a signal current between the optoelectronic device and a device external to the TO package, and a second side for transmitting a ground current between the TO package and the external device. For a predefined operating frequency range, the impedance of the circuit interconnect approximately matches the impedance of the signal leads of the TO package and also approximately matches the impedance of the device external to the TO package. The optoelectronic device may include a laser diode or a photo diode. In addition, the present invention is an optoelectronic transceiver including a transmitter optoelectronic assembly and a receiver optoelectronic assembly. The transmitter optoelectronic assembly includes a transmitter TO package and a transmitter circuit interconnect, and the receiver optoelectronic assembly includes a receiver TO package and a receiver circuit interconnect.
1. An optoelectronic assembly comprising:
a plurality of transistor outline packages housing a like plurality of optoelectronic devices;
a plurality of circuit interconnects, each respective circuit interconnect coupled to a respective one of the optoelectronic devices and a respective one of the transistor outline packages, wherein each respective circuit interconnect comprises an elongate, flexible insulator including:
a plurality of data signal traces on a first side for transmitting a plurality of data signal currents between the respective optoelectronic device and a respective device external to the respective transistor outline package; and
a conductor on a second side for transmitting a ground current between the respective transistor outline package and the respective device external to the respective transistor outline package; the conductor having a current path that runs parallel to the plurality of data signal traces; and
a circuit board on which each of the respective devices external to the transistor outline packages is mounted;
wherein the insulator, the conductor and the data signal traces of each of the plurality of circuit interconnects are configured so that, for operation in a predefined range of frequencies above 3 GHz, impedance of the circuit interconnect approximately matches impedance of the respective device external to the transistor outline package.
2. The optoelectronic assembly of claim 1 , wherein each transistor outline package includes a plurality of signal leads; and
the insulator, the conductor and the data signal traces of each of the plurality of circuit interconnects are configured so that, for operation in the predefined range of frequencies, impedance of the circuit interconnect approximately matches impedance of the signal leads of the respective transistor outline package.
3. The optoelectronic assembly of claim 2 , wherein the impedance each signal lead of the plurality of signal leads of each transistor outline package approximately matches impedance of circuitry within the transistor outline package.
4. The optoelectronic assembly of claim 1 , wherein
each transistor outline package includes a signal lead; and
each transistor outline package of the plurality of transistor outline packages includes a pedestal shaped to be concentrically positioned around at least a portion of the signal lead.
5. The optoelectronic assembly of claim 1 , wherein
a first transistor outline package of the plurality of transistor outline packages includes a signal lead; and
the first transistor outline package includes a pedestal shaped to be concentrically positioned around at least a portion of the signal lead.
6. The optoelectronic assembly of claim 1 , wherein the conductor on the second side of each circuit interconnect directly contacts the respective transistor outline package.
7. The optoelectronic assembly of claim 1 , wherein each transistor outline package includes a signal lead electrically connected to the optoelectronic device housed in the transistor outline package, a concentric dielectric ring situated around the signal lead, and a concentric ground ring situated around the dielectric ring, the concentric ground ring directly contacting the conductor on the second side of the respective circuit interconnect.
8. An optoelectronic transceiver comprising:
a light source housed in a transmitter transistor outline package;
a detector housed in a receiver transistor outline package;
a transmitter circuit interconnect coupled to the light source and the transmitter transistor outline package, wherein the transmitter circuit interconnect includes:
a first data signal trace on a first side for transmitting data signal current from the light source to a first device external to the transistor outline package; and
a first conductor on a second side for transmitting a ground current between the transmitter transistor outline package and the first device external to the transistor outline package; the first conductor having a current path that runs parallel to the first data signal trace; wherein the first conductor and the first data signal trace are configured so that, for operation in a predefined range of frequencies above 3 GHz, impedance of the transmitter circuit interconnect approximately matches impedance of the light source housed in the transmitter transistor outline package;
a receiver circuit interconnect coupled to the detector and the receiver transistor outline package, wherein the receiver circuit interconnect includes:
a second data signal trace on a first side for transmitting signal current from the detector to a second device external to the transistor outline package; and
a second conductor on a second side for transmitting a ground current between the receiver transistor outline package and the second device external to the transistor outline package; the second conductor having a current path that runs parallel to the second data signal trace; wherein the second conductor and the second data signal trace are configured so that, for operation in a predefined range of frequencies above 3 GHz, impedance of the receiver circuit interconnect approximately matches impedance of the detector housed in the receiver transistor outline package.