Preliminary Technical Data UG-1828
Rev. PrC | Page 127 of 338
Figure 130. Constant Step Mode
GPIO MODE
Another method to control the transmitter attenuation block is through GPIO mode. In this mode, two GPIO pins are used to increment
or decrement the current attenuation value. An API command “adi_adrv9001_Tx_Attenuation_PinControl_Configure()” is provided to
the user to configure the GPIO pins and set the step size. A typical output power transient is shown in Figure 131.
Figure 131. GPIO Incr/Decr Mode
Power Amplifier Protection
In the transmitter signal chain, two power amplifier protection mechanisms are provided to protect the power amplifier from excessive
peak or average power excursions. Note these features are not fully supported in the current release.
Power Monitor
Power monitor is one of the power amplifier protection methods, and it uses the transmitter attenuation block to adjust the power by
continuously monitoring the output power of the Tx datapath.
Through API commands, the user can enable power amplifier protection and set configuration parameters such as average and peak
power thresholds. The average power is accumulated over a specified integration time, and an error flag is asserted if it exceeds the
threshold. In addition, the instantaneous or peak power is detected and the error flag is asserted if a specified number of peaks is
exceeded. The power amplifier error flag can be read via an API command. The power delivered to the power amplifier is automatically
reduced if the error flag is asserted. In the scenario depicted in Figure 132, the error flag is asserted after two power peaks were detected.
The power amplifier power is automatically ramped down to max attenuation. Note that the average power did also exceed its threshold,
but not for long enough.
CONST_STEP_MODE_STEP_SIZE
DESIRED Tx
ATTENUATION
FULL-SCALE OUTPUT POWER
Tx OUTPUT POWER
CONST_STEP_MODE_WAIT_DURATION
TX_ATTENUATION<9:0>
24159-090
TX_INCR_DECR_WORD
TX_INCR_GPIO
TX_DECR_GPIO
Tx OUTPUT POWER
24159-091
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