User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 41
Original 11/97
CDMA TX Bias Tuning
The purpose of this tuning operation is to calibrate the Power Amplifiers
bias current limit.
This tuning is needed if the Power Amplifier (V113) or any transistor in the
TX chain (V110 – V112) is changed.
Definition of Tuning
This tuning sets the bias current limits on the CLY–10 (V113) final PA gain
stage. Bias current on the CLY–10 is dynamic in CDMA operation. The
TXB PDM is used to set this bias. Low power is defined as less than or
equal to +10 dBm of output CDMA TX bandpower. For the low power
case the bias is set to provide 100 mA of current to the CLY–10. Max
Power is defined as greater than or equal to +23 dBm of output CDMA TX
bandpower. For the Max Power case the bias is set to provide 250 mA of
current to the CLY–10. Between Low and Max Power the bias current
ramps up linearly from 100 to 250 mA. These currents described are the
amount of current draw above the quiescent state of the phone in CDMA
mode. The figure below better describes the TXB Slope.
CLY–10 Bias Current vs. CDMA TX Output Power
250mA
CLY–10 Bias
Current
100 mA
+10 dBm 23 dBm
TXB Slope
Figure 13. CDMA TX Output power
Note: This Tuning may need to be repeated several times to ensure proper
calibration. It is recommended that each step be reverified since this tuning step will
affect battery performance.