Preliminary Technical
Data
Rev. PrA | Page 63 of 82
The 64 bit ‘OR’ed mask that consists of
tracking calibrations to enable/ disable
(ADI_ADRV9025_TRACK_TX1_CLGC |
ADI_ADRV9025_TRACK_TX2_CLGC |
ADI_ADRV9025_TRACK_TX3_CLGC |
ADI_ADRV9025_TRACK_TX4_CLGC)
Indicates whether the mask value passed
in enableMask parameter is to be used for
enabling or disabling the tracking
ADI_ADRV9025_TRACKING_CAL_ENABLE
Similarly, to disable the CLGC tracking calibration, the user can set the argument enableDisableFlag to an enumeration valud
ADI_ADRV9025_TRACKING_CAL_DISABLE in order to disable the CLGC tracking calibration on the requested channels.
Please note that when the CLGC tracking calibration is enabled, the CLGC doesn’t actively control the loop gain. The user has to
explicitly configure the loop gain control enable via adi_adrv9025_ClgcConfigSet() API in order to enable actively control the
CLGC loop gain. Details regarding the CLGC modes of operation are captured in the CLGC Modes Of Operation
NOTE: The CLGC tracking calibration works in synchronization with the DPD algorithm, and the CLGC is scheduled once per
second by the firmware.
CLGC MODES OF OPERATION
The CLGC functionality can operate in two modes
1. Passive loop gain measurement: This mode of operation is typically activated to determine initial operating point of the
PA. When a transmitter is activated, the user determines the PA operating point by sending traffic and measuring the overall
loop gain from ORx to Tx. During this stage, the user can take advantage of the passive loop gain measurement mode, in
which the CLGC algorithm simply measures the loop gain without actively adjusting the Tx front end attenuation. Once the
ideal operating point is determined, the user can then enable active loop gain control mode.
2. Active Loop Gain Control: In this mode, the CLGC measures the loop gain from ORx to Tx baseband, and adjusts the Tx front
end gain to maintain the loop gain. This mode of operation is typically activated during runtime once the initial operating
points are determined, and the initial ORx gain, Tx attenuation settings are configured. For the active loop gain control mode,
the user is required to configure the expected loop gain using the API adi_adrv9025_ClgcConfigSet() through the
parameter clgcExpectedLoopGain_dB in the data structure adi_adrv9025_ClgcConfig_t.
The user can select the CLGC mode of operation through the adi_adrv9025_ClgcConfigSet() API, using the parameter
clgcEnableGainControl in adi_adrv9025_ClgcConfig_t data structure as shown in Table 3
Table 36. CLGC Mode of operation configuration
Passive loop gain measurement
Figure 65 captures a typical CLGC bring up sequence during which the passive and active loop gain control modes are active at
various stages.
In the passive loop gain measurement mode, the user can retrieve the ORx RMS power and Tx RMS power as well as the loop gain
estimated by the CLGC algorithm using the API adi_adrv9025_ClgcStatusGet(). The structure adi_adrv9025_ClgcStatus_t has
members clgcLoopGain, clgcTxRmsPower, clgcOrxRmsPower which can be monitored to adjust the initial operating point of
the PA, and determine the desired loop gain.
The passive loop gain measurement mode is mostly used in a factory calibration setting. The optimal operating point for the PA is
determined, the loop gain, Tx attenuation and ORx gain values are noted, and the values are used in the field.
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