Technique for photonic analog-to-digital signal conversion
View Patent ↗In an inventive photonic analog-to-digital signal converter (ADC), multiple opto-electric sampling devices are employed to successively sample an analog signal input. Optical clock signals having the same frequency but different clock phases are used, which are associated with the opto-electric sampling devices, respectively. Each sampling device takes samples of the analog signal input in response to the optical clock signal associated therewith. The resulting samples are processed to produce quantized samples. The inventive ADC outputs a digital signal representing the quantized samples.
1. An analog-to-digital signal conversion apparatus, comprising:
an optical element for providing a plurality of optical clock signals having an identical frequency, at least one of the optical clock signals having a phase offset from a second one of the optical clock signals, the phase offset having a selected value based at least on the number of optical clock signals provided;
a plurality of sampling devices responsive to the optical clock signals for successively sampling an analog signal input to provide samples thereof, each of the optical clock signals being associated with a respective one of the sampling devices, at least one of the sampling devices being adapted to generate an electrical current whose amperage represents values of samples taken by the at least one sampling device; and
one or more demultiplexers for distributing, in a time-controlled manner, the electrical current from the at least one sampling device to a plurality of processing elements for generating a digital signal representing values of quantized samples, which arc derived from the sample values represented by the amperage of the electrical current.
2. The apparatus of claim 1 wherein the at least one optical clock signal is a delayed version of the second optical signal.
3. The apparatus of claim 1 wherein the plurality of optical clock signals are derived from an optical clock signal generated from a mode lock laser source.
4. The apparatus of claim 1 further comprising at least one optical delay element for providing the at least one optical signal.
5. The apparatus of claim 4 wherein the optical delay element comprises a predetermined length of an optical fiber.
6. The apparatus of claim 1 wherein at least one of the sampling devices comprises an opto-electric track and hold amplifier (THA).
7. The apparatus of claim 1 wherein the identical frequency varies with the number of sampling devices used.
8. The apparatus of claim 1 wherein the samples by the at least one sampling device are sub-sampled before the the digital signal is generated.
9. The apparatus of claim 1 wherein at least one of the processing elements comprises an electronic analog-to-digital signal converter.
10. The apparatus of claim 1 wherein the optical element comprises an optical splitter.
11. An analog-to-digital signal conversion apparatus, comprising:
a plurality of sampling devices for successively sampling an analog signal input in response to different optical clock signals, respectively, at least one of the sampling devices being adapted to generate an electrical current whose amperage represents values of samples taken by the at least one sampling device; and
one or more demultiplexers for distributing, in a time-controlled manner, the electrical current from the at least one sampling device to a plurality of processing elements for generating a digital signal representing values of quantized samples, which are derived from the sample values represented by the amperage of the electrical current.
12. The apparatus of claim 11 wherein at least one of the sampling devices comprises an opto-electric THA.
13. The apparatus of claim 11 wherein at least one of the demultiplexers comprising a plurality of switch devices.
14. The apparatus of claim 13 wherein a plurality of clock signals are provided, each switch device being associated with a respective one of the clock signals, each switch device being turned on or off according to the clock signal associated therewith.
15. The apparatus of claim 11 wherein the samples taken by the at least one sampling device are sub-sampled by the plurality of the processing elements.
16. The apparatus of claim 11 wherein at least one of the processing elements is an electronic analog-to-digital signal converter.
17. A method for converting an analog signal input to a digital signal output, comprising:
providing a plurality of optical clock signals having an identical frequency, at least one of the optical clock signals having a phase offset from a second one of the optical clock signals, the phase offset having a selected value based at least on the number of optical clock signals provided;
using a plurality of sampling devices which are responsive to the optical clock signals to successively sample an analog signal input to provide samples thereof, each of the optical clock signals being associated with a respective one of the sampling devices;
generating an electrical current whose amperage represents values of samples taken by at least one of the sampling device; and
distributing, in a time-controlled manner, the electrical current from the at least one sampling device to a plurality of processing elements for generating a digital signal representing values of quantized samples, which are derived from the sample values represented by the amperage of the electrical current.
18. The method of claim 17 wherein the at least one optical clock signal is a delayed version of the second optical signal.
19. The method of claim 17 wherein the identical frequency varies with the number of sampling devices used.
20. The method of claim 17 wherein the samples by the at least one sampling device are sub-sampled before the the digital signal is generated.