User's Manual

TB8100 Calibration Kit User’s Manual Calibrating the Forward and Reverse Detector Bias Voltages 29
Note: You must perform the calibration in sequence from the lowest
to the highest step. The DAC setting must be greater than the
previous one otherwise the value will not be stored in the PA, and
you cannot move to the next line.
6. When you have completed adjusting the DAC settings, click Finish.
When you have finished, the icon on the PA Calibration tab indicates that
this task is complete.
Troubleshooting Tips
DAC Settings When you adjust the DAC settings, the values for the DAC Setting, Coupler
Fwd Voltage, and Control Voltage should always increase as the power level
increases. If these values do not increase, there is either a fault with the PA or
the previous step was not calibrated correctly. If you make a mistake in the
calibration table, you must start again from step 1.
Control Voltage The Control Voltage is shown in the table to indicate the operation point
within the power control loop. The range of the control voltage is from 0 V to
7.5 V. If the control voltage reaches its limit before achieving maximum power
in the table, this indicates either a faulty gain stage in the PA or low RF input
power to the PA.
VSWR The VSWR (Voltage Standing Wave Ratio) is monitored at the RF output of
the PA during calibration. The software will not allow calibration into a load
VSWR > 1.3:1. If a calibration step cannot be stored, check that the load
VSWR is <1.3:1. It is recommended that the load should have an input
VSWR <1.2:1.
Calibrating the Forward and Reverse Detector Bias Voltages
The RF detectors, used for measuring the forward and reverse power, operate
with a small bias current. The resulting bias voltage from each detector (with
no RF present) is read and stored inside the PA. These voltages are used when
calculating the Antenna VSWR (Voltage Standing Wave Ratio).
You should calibrate the forward and reverse detector bias voltages:
■ If the Low Pass Filter (LPF)/directional coupler PCB module is replaced
■ After servicing of any components in the detector circuitry (such as the
detector diodes) on the LPF/ directional coupler PCB
To calibrate the forward and reverse detector bias voltages
1. Ensure you are already connected to the base station.
2. Select the PA Calibration tab, and double-click Calibrate Fwd/Rev
Detector Bias Voltages.
3. Ensure that the PA is not transmitting and that there is no RF source present
at the PA RF input or output by disconnecting the input SMA connector
on the PA front panel and the ‘N’ type output connector from the rear of
the PA. Click Finish.
When you have finished, the icon on the PA Calibration tab indicates that
this task is complete.