N1078A Optical CDR Test Setups

Clock Recovery
N1078A

The illustrations in this topic represent a variety of optical clock recovery using the N1078A. In some situations, the length of the cables used can impact measurement accuracy. For more information, download the N107x-series user's guide at www.keysight.com.

Circled numbers in this figure identify items from the electrical phase matching kits. Optional equalizers can be added to open a closed eye for clock recovery.

Precision Timebase and Trigger Connections from an N107x-Series DCA-M

When using an N107x-series DCA-M clock recovery module with an N1060A or 86108A/B, know that the signal from the N107x's Aux Clock Out connector has significantly lower jitter than the signal from the N107x's Recovered Clock Out connector. Therefore:

  • Connect the N107x's Aux Clock Out (lower jitter) to the DCA-X's or N1060A's Precision Timebase Input, and
  • Connect the N107x's Recovered Clock Out to the DCA-X's Trigger Input.

Example Setup 1. Single-Ended Input, N1078A-SXT, DCA-M Scope

This example setup shows an N1078A-SXT connected to an N1094B oscilloscope with a single-ended electrical input signal. The microwave pickoff is used to tap a portion of the input signal as an input to the clock recovery module.

Example Setup 2. Differential Input, N1078A-SXT, DCA-M Scope

This example setup shows an N1078A-SXT connected to an N1094B oscilloscope with a differential input signal. Two microwave pickoffs are used to tap a portion of the input signal as an input to the clock recovery module.

Example Setup 3. Differential Input, N1078A-SXT, DCA-X Scope

This example setup shows an N1078A-SXT connected to a DCA-X oscilloscope with a differential input signal. The oscilloscope has an N1045A receiver module and an 86107A precision timebase. Two microwave pickoffs are used to tap a portion of the input signal as an input to the clock recovery module.

Example Setup 4. Single-Mode Input, N1078A-SXT, 86105D

This example setup shows an N1078A-SXT connected to a DCA-X oscilloscope. The oscilloscope has an 86105D receiver module which has a multimode optical input connector. The N1078A has single-mode optical input connector. Since the N1078A-SXT does not have an internal optical splitter, the user must supply their own.

Example Setup 5. Single-Mode Input, N1078A-S50, DCA-M Scope

This example setup shows an N1078A-S50 connected to an N1092E oscilloscope. Single-mode fiber is connected to the N1078A-S50’s single-mode input connector. Since the N1092-series oscilloscopes has a multimode input, you can use a multimode patchcord in most cases.

Example Setup 6. Single-Mode Input, N1078A-S50, 86116C

This example setup shows an N1078A-S50 connected to a DCA-X oscilloscope with an 86116C.