AD9361 Reference Manual UG-570
| Page 55 of 128
TRANSMIT POWER CONTROL
OVERVIEW
The AD9361 transceiver uses an accurate and efficient method
of transmit power control (TPC) that involves a minimum of
interaction with the BBP. This section shows how to setup the
registers for the various modes and how to use transmit power
control during normal operation.
Tx ATTENUATION WORDS
A single 9-bit word controls the attenuation of a particular
transmitter path. The internal lookup table is 360(d) entries
deep and the overall transmit path attenuation step size is
0.25 dB/LSB across the entire table. An attenuation word of zero
results in 0 dB of attenuation. The value of 359(d) results in an
overall attenuation of 89.75 dB. The lookup table is hard-coded
in the AD9361 and it not programmable.
ATTENUATION WORD UPDATE OPTIONS
The BBP can write attenuation words at any time using the
ad9361_set_tx_attenuation function. There are two choices for
when the new attenuation word is implemented. The default
mode will implement the attenuation as soon as the function is
executed. The other option is to write the new attenuation
word, but require the AD9361 go through an alert cycle before
the word is implemented.
Additionally, setting the Sel Tx1 and Tx2 bit causes the AD9361
to use the Tx1 attenuation word for both transmitters. The bit is
normally cleared.
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