The 86108A Precision Waveform Analyzer module is a dual-channel electrical module with integrated, compliant clock recovery, and a built-in precision time base. This is a double-wide module that fills both slots in the mainframe. The 86108A requires an N1000A, 86100D, or 86100C. It does not work with an 86100A or 86100B. For optimum performance, N1000A-PLK or 86100D-ETR should be used with the Research and Development Package license installed (or legacy Enhanced Jitter Analysis Software, 86100D-200). Without these options, the features provided with the 86108A module will be reduced.

• Front-Panel Features
• Block Diagram

Automatic Relock

If the clock recovery module loses lock, the trigger becomes asynchronous with the data and the instrument will not display a correctly triggered waveform. By default, when lock is lost, the instrument automatically tries to re-establish lock. Automatic relocking is most helpful when probing a device under test. You can turn off or on automatic relocking from the Clock Recovery setup dialog. Loss of lock, or false lock, conditions may be caused by unusual patterns with a large amount of consecutive 1's or 0's. If the module loses lock during any procedure or measurement, reestablish lock and then repeat the procedure or measurement. For example, if lock is lost while saving a pattern waveform to a file, the data stored in the file will be corrupt.

Locking on the Data Rate

When using the module, you must specify the symbol rate of the clock to be recovered and lock the module on the symbol rate. Under two conditions, the module may lock on a symbol rate other than the specified rate. In the first condition, lock can occur if the entered symbol rate is an integer multiple of the actual symbol rate of the signal. The second condition occurs because the acquisition range is broad (greater than ±5000 PPM). This makes it possible for the module to lock on a signal that is higher or lower than the selected value. For example, if you select a 2.48832 GBd symbol rate but the signal is actually 2.5 GBd, the module may still lock on the signal.

Loop Bandwidth and Jitter

When measuring jitter relative to the recovered clock, jitter that is present on both the data and the recovered clock can not be detected by the instrument. Jitter that is within the clock recovery module's loop bandwidth appears on the recovered clock. Jitter that is outside of the loop bandwidth does not appear on the recovered clock and can be detected on the data.

Specific jitter frequencies in the vicinity of the loop bandwidth may appear amplified or attenuated due to the scope timebase delay and clock recovery group delay. The electrical through-path does not have a delay line. Compensation can be made, by adding an electrical cable between the electrical output and the vertical channel. However, this may affect signal quality.

Aux Input

86108A Option 400 modules include a front-panel auxiliary clock recovery input. This front-panel input can provide improved performance in the following situations:

• Marginal Input Signals
• Improved Phase Noise Measurements
• Measurements on Data Rates Above the 14.2 GBd Channel Input Limits

Available Options

Item	Description
86108A–001	Two 3.5 mm phase trimmers for external skew adjustment
86108A–002	Two precision 3.5 mm 18 inch cables
86108A–100	Dual 33 GHz electrical channels with internal clock-data recovery
86108A–200	Clock recovery input symbol rate range of 0.05 GBd to 14.2 GBd. This option is automatically included with every 86108A module. The module can not be ordered without this option.
86108A–300	Clock recovery adjustable loop bandwidth continuous-tuning range of 15 kHz to 10 MHz. Available loop bandwidth settings also depend on the symbol rate of the input signal. This option is automatically included with every 86108A module. The module can not be ordered without this option.
86108A–400	Auxiliary Clock Recovery Input. This option is automatically included with every 86108A module.

See Also

• Available Accessories
• AUX Input
• Modules