N1078A Optical CDR Test Setups

DCA-M Tasks
N1078A CDR

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, 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-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.