Optical transceiver with equalization and controllable laser interconnection interface
An optical transceiver includes an optical IC coupled to a processor IC. For transmit, the optical IC can be understood as a transmitter IC including a laser device or array. For receive, the optical IC can be understood as a receiver IC including a photodetector/photodiode device or array. For a transmitter IC, the processor IC includes a driver for a laser of the transmitter IC. The driver includes an equalizer that applies high frequency gain to a signal transmitted with the laser device. For a receiver IC, the processor IC includes a front end circuit to interface with a photodetector of the receiver IC. The front end circuit includes an equalizer that applies high frequency gain to a signal received by the receiver IC. The driver can be configurable to receive a laser having either orientation: ground termination or supply termination.
1. An optical transceiver system comprising:
a laser device; and
a driver circuit to drive the laser device, the driver circuit comprising an equalizer that generates high frequency gain to a signal to be transmitted via the laser device, wherein the equalizer is embedded within the driver circuit.
2. The optical transceiver system of claim 1 , wherein the laser device comprises a VCSEL (vertical cavity surface emitting laser).
3. The optical transceiver system of claim 1 , wherein the laser device includes an array of lasers, and the driver circuit includes a driver circuit for each laser in the array.
4. The optical transceiver system of claim 1 , wherein the equalizer comprises a feed forward equalizer circuit.
5. The optical transceiver system of claim 1 , wherein the driver circuit includes the equalizer in a high-speed path of the signal.
6. The optical transceiver system of claim 1 , wherein the driver circuit comprises a modulator including the equalizer.
7. The optical transceiver system of claim 1 , wherein the driver circuit drives the laser device at a frequency higher than its rated bandwidth.
8. An optical transceiver system comprising:
a photo detector device having a first bandwidth to receive an optical signal having a second bandwidth, the first bandwidth being lower than the second bandwidth;
a transimpedance amplifier (TIA) coupled to the photo detector device to convert the optical signal received at the photo detector device into an electrical signal; and
an equalization circuit coupled to the TIA to generate a high frequency gain in the electrical signal to compensate for the first bandwidth of the photo detector.
9. The optical transceiver system of claim 8 , wherein the equalization circuit comprises a continuous time linear equalizer (CTLE) circuit.
10. The optical transceiver system of claim 8 , wherein the photo detector device includes an array of photodiodes, and the equalization circuit includes applies equalization for each photodiode of the array.
11. The optical transceiver system of claim 8 , wherein the photo detector device operates at a frequency higher than its rated bandwidth.
12. An optical small form factor pluggable (SFP) transceiver comprising:
a printed circuit board (PCB) including
pads to electrically connect to a peripheral port;
an optical transmitter integrated circuit (IC) disposed on the PCB;
an optical receiver IC disposed on the PCB; and
a processor IC disposed on the PCB, including
signal processing logic,
a driver circuit to drive a VCSEL (vertical cavity surface emitting laser) of the optical transmitter IC, the driver circuit comprising an equalizer that applies high frequency gain to a signal to be transmitted via the VCSEL, wherein the equalizer is embedded within the driver circuit; and
an optical receiver front end circuit including a transimpedance amplifier (TIA) coupled to the optical receiver IC to convert an optical signal received at a photodiode of the optical receiver IC into an electrical signal, and an equalization circuit coupled to the TIA to apply high frequency gain to the electrical signal; and
a connector housing to at least partially enclose the printed circuit board.
13. The SFP transceiver of claim 12 , wherein the optical transmitter IC includes a VCSEL array and the optical receiver IC includes a photodiode array, wherein the connector housing includes an array of lenses corresponding to the array of VCSELs and the array of photodiodes.
14. The SFP transceiver of claim 12 , wherein the driver equalizer comprises a feed forward equalizer circuit, and wherein the equalization circuit comprises a continuous time linear equalizer (CTLE) circuit.
15. The SFP transceiver of claim 12 , wherein both the optical transmitter IC and the optical receiver IC operate at a frequency higher than their respective rated bandwidths.
16. An optical transmitter device comprising:
a first connection area to connect to a source terminated laser device; a second connection area to connect to a ground terminated laser device;
a signal line coupled to one of the first connection area and the second connection area; and
a driver circuit coupled to the signal line to drive the laser device, including providing an output signal to the signal line, wherein the driver circuit includes a variable current source configured to produce a first current when the signal line is connected to the first connection area to drive the source terminated laser device, or to produce a second current different from the first current when the signal line is connected to the second connection area to drive the ground terminated laser device.
17. The optical transmitter device of claim 16 , the driver circuit further comprising an inductor in a signal path of the driver circuit coupled to the signal line, the inductor configured to suppress reflection current.
18. The optical transmitter device of claim 17 , the driver circuit further comprising a capacitor in parallel with the variable current source.
19. The optical transmitter device of claim 16 , the driver circuit further comprising an equalizer to apply high frequency gain to an optical signal to be transmitted by the laser device.