Switchable bandwidth lowpass filter

1. A switchable optoelectronic receiver having at least two different operational data bandwidths and a switchable lowpass filter for selecting between said two bandwidths, wherein said switchable lowpass filter comprises parallel elements and a switching element, said parallel elements comprising a first capacitor and a resistor, said resistor being in parallel with said first capacitor; said switching element comprising at least a second capacitor and switching means, said second capacitor disposed parallel to said first capacitor when said switching means is engaged.

2. The switchable optoelectronic receiver recited in claim 1 , wherein said switching means comprises a diode.

3. The switchable optoelectronic receiver recited in claim 1 , wherein said switching means is selected from the group consisting of single-pole switches, diodes, transistors, pin diodes, and relays.

4. The switchable optoelectronic receiver recited in claim 1 , wherein said switching means and said second capacitor are combined.

5. The switchable optoelectronic receiver recited in claim 4 , wherein said switching means comprises a variable capacitance diode.

6. The switchable optoelectronic receiver recited in claim 1 , wherein said switchable lowpass filter is a variable capacitance lowpass filter.

7. The switchable optoelectronic receiver recited in claim 1 , wherein said switchable lowpass filter is a variable resistance lowpass filter.

8. The switchable optoelectronic receiver recited in claim 1 , further comprising a switching input circuit for controlling said switchable lowpass filter.

9. The switchable optoelectronic receiver recited in claim 1 , wherein said at least two different operational data bandwidths are 0.8 through 1.5 Gb/s and 1.6 through 3.2 Gb/s.

10. The switchable optoelectronic receiver recited in claim 1 , wherein said at least two different operational data bandwidths are 1.0625 Gb/s±100 ppm and 2.125 Gb/s±100 ppm.

11. The switchable optoelectronic receiver recited in claim 1 , further comprising means for autodetecting said operational data bandwidth.

12. The switchable optoelectronic receiver recited in claim 11 , wherein said autodetecting means provides a control signal to said means for selecting between said two bandwidths.

13. The switchable optoelectronic receiver recited in claim 11 , wherein said means for autodetecting comprises a first and second data channel, said first data channel input to said means for selecting between said two bandwidths, said second data channel input to a post-amplifier and filter and then to a detector/rectifier/comparator to generate a control signal, said control signal provided to said means for selecting between said two bandwidths.

14. The switchable optoelectronic receiver of claim 1 , further comprising means for autodetecting said operational data bandwidth, wherein said means for autodetecting comprises a first and second data channel, said first data channel providing input to said switchable lowpass filter, and said second data channel providing input to a post-amplifier and filter and then to a detector/rectifier/comparator to thereby generate a control signal, wherein said control signal is provided to said switchable lowpass filter.

15. A switchable optoelectronic transceiver having at least two different operational bandwidths and switchable lowpass filter for selecting between said two bandwidths, wherein said switchable lowpass filter comprises parallel elements and a switching element, said parallel elements comprising a first capacitor and a resistor, said resistor being in parallel with said first capacitor; said switching element comprising at least a second capacitor and switching means, said second capacitor disposed parallel to said first capacitor when said switching means is engaged.

16. The switchable optoelectronic transceiver of claim 15 , wherein said transceiver includes a switchable optoelectronic transmitter shaving said at least two different emission bandwidths, and wherein said transmitter includes said switchable lowpass filter for selecting between said two bandwidths.

17. The switchable optoelectronic transceiver recited in claim 16 , wherein said switching means comprises a diode.

18. The switchable optoelectronic transceiver recited in claim 16 , wherein said switching means is selected from the group consisting of single-pole switches, diodes, transistors, pin diodes, and relays.

19. The switchable optoelectronic transceiver recited in claim 16 , wherein said switching means and said second capacitor are combined.

20. The switchable optoelectronic transceiver recited in claim 19 , wherein said switching means comprises a variable capacitance diode.

21. The switchable optoelectronic transceiver recited in claim 16 , wherein said switchable lowpass filter comprises a variable capacitance lowpass filter.

22. The switchable optoelectronic transceiver recited in claim 16 , wherein said switchable lowpass filter comprises a variable resistance lowpass filter.

23. The switchable optoelectronic transceiver recited in claim 16 , further comprising a switching input circuit for controlling said means for selecting between said two bandwidths.

24. The switchable optoelectronic transceiver recited in claim 23 , wherein said switching means comprises a diode.

25. The switchable optoelectronic transceiver recited in claim 23 , wherein said switching means is selected from the group consisting of single-pole switches, diodes, transistors, pin diodes, and relays.

26. The switchable optoelectronic transceiver recited in claim 23 , wherein said switching means and said second capacitor are combined.

27. The switchable optoelectronic transceiver recited in claim 26 , wherein said switching means comprises a variable capacitance diode.

28. The switchable optoelectronic transceiver recited in claim 23 , further comprising a switching input circuit for controlling said switchable lowpass filter.

29. The switchable optoelectronic transceiver recited in claim 23 , wherein said switchable lowpass filter comprises a variable capacitance lowpass filter.

30. The switchable optoelectronic transceiver recited in claim 23 , wherein said switchable lowpass filter comprises a variable resistance lowpass filter.

31. The switchable optoelectronic transceiver recited in claim 16 , wherein said at least two different operational data bandwidths are 0.8 through 1.5 Gb/s and 1.6 through 3.2 Gb/s.

32. The switchable optoelectronic transceiver recited in claim 16 , wherein said at least two different operational data bandwidths are 1.0625 Gb/s±100 ppm and 2.125 Gb/s±100 ppm.

33. The switchable optoelectronic transceiver recited in claim 16 , further comprising means for autodetecting said operational data bandwidth.

34. The switchable optoelectronic transceiver recited in claim 33 , wherein said autodetecting means provides a control signal to said means for selecting between said two bandwidths.

35. The switchable optoelectronic receiver recited in claim 33 , wherein said means for autodetecting comprises a first and second data channel, said first data channel input to said means for selecting between said two bandwidths, said second data channel input to a post-amplifier and filter and then to a detector/rectifier/comparator to generate a control signal, said control signal provided to said means for selecting between said two bandwidths.

36. The switchable optoelectronic transceiver recited in claim 15 , wherein said at least two different operational data bandwidths are 0.8 through 1.5 Gb/s and 1.6 through 3.2 Gb/s.

37. The switchable optoelectronic transceiver recited in claim 15 , wherein said at least two different operational data bandwidths are 1.0625 Gb/s±100 ppm and 2.125 Gb/s±100 ppm.

38. The switchable optoelectronic transceiver recited in claim 15 , further comprising means for autodetecting said operational data bandwidth.

39. The switchable optoelectronic transceiver recited in claim 38 , wherein said autodetecting means provides a control signal to said means for selecting between said two bandwidths.

40. The switchable optoelectronic transceiver recited in claim 38 , wherein said means for autodetecting comprises a first and second data channel, said first data channel input to said means for selecting between said two bandwidths, said second data channel input to a post-amplifier and filter and then to a detector/rectifier/comparator to generate a control signal, said control signal provided to said means for selecting between said two bandwidths.

41. The switchable optoelectronic transceiver of claim 16 , further comprising means for autodetecting said operational data bandwidth, wherein said means for autodetecting comprises a first and second data channel, said first data channel providing input to said switchable lowpass filter, and said second data channel providing input to a post-amplifier and filter and then to a detector/rectifier/comparator to thereby generate a control signal, wherein said control signal is provided to said switchable lowpass filter.

42. The switchable optoelectronic transceiver of claim 15 , further comprising means for autodetecting said operational data bandwidths, wherein said means for autodetecting comprises a first and second data channel, said first data channel providing input to said a switchable lowpass filter, and said second data channel providing input to a post-amplifier and filter and then to a detector/rectifier/comparator to thereby generate a control signal, wherein said control signal is provided to said switchable lowpass filter.