FM In-Band Offset Calibration

(E8267D, E8663D with Option UNT and without Option UNY, and E8257D with Option UNT and without Option UNY and without Option HNY, and E8257N Only)

This adjustment calibrates the offsets associated with changes to the FM_IN_BAND_DAC on the A6 Frac-N. Changes in the FM_IN_BAND_DAC causes non-linear changes in the noise gain on the FM_IN_BAND_DAC operation amplifier. These changes in noise gain appear as changes in the RF output frequency.

During this adjustment, the instrument is set up so the FM1, Ext1, and DCFM paths are selected. The FM_IN_BAND_DAC and FM_IN_BAND_OFFSET_DACs are set to 0 and the RF output frequency is measured. The FM_IN_BAND_OFFSET_DAC is set to 4095 and the RF output frequency is measured again. These two measured values are used to determine the slope and offset associated with an FM_IN_BAND_DAC value of 0.

Then, the FM_IN_BAND_DAC is set to 299 and the FM_IN_BAND_OFFSET_DAC set to 0 and the RF output frequency is measured. The FM_IN_BAND_OFFSET_DAC set to 4095 and the RF output frequency measured again. These two measurements are used to determine the slope and offset associated with an FM_IN_BAND_DAC value of 299.

The slope and offset values for 0 and 299 FM_IN_BAND_DAC settings are used to determine the FM_IN_BAND_OFFSET_DAC.

Test Equipment

Preferred Model

Alternate Model(s)

Frequency Counter

53230A Opt 010 and (106 or 115)

53132A Opt 010 and (050 or 124)

 

Connections and Setup Procedures

  • With the exception of the 53132A Option 050 or 124, or the 53230A Option 106 or 115 frequency counter, all test equipment requires a 30 minute warmup period to ensure accurate performance.

  • The frequency counter must be plugged into the AC power line for at least 24 hours before testing begins.

  • In the following test setup, cables are designated as solid lines and direct connections are designated as dashed lines.

  1. Connect all test equipment as shown.

  2. Connect GPIB cables to all GPIB-controlled test equipment.

  3. While performing this adjustment, follow all instructions on the controller display.

 

Setup for FM In-Band Offset Calibration

 

In Case of Difficulty

If this adjustment fails, perform the following steps in order:

  1. Check the equipment setup (see above). If the setup is incorrect, make the necessary corrections and rerun the adjustment.

  2. If this adjustment fails with the equipment set up properly, refer to the troubleshooting section of the signal generator's service guide. If you do not have a printed copy of the service guide (Option OBW), one is available either on the CD-ROM that came with your signal generator shipment or on the Keysight Website.

  3. If you cannot correct the problem using the troubleshooting procedures in the Service Guide, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.