Analog Devices ADRV9005 Reference Manual page 144

Reference Manual
TRANSMITTER SIGNAL CHAIN
Table 61. Sample Rows from the Tx Gain Table
Transmitter Total Transmitter
Attenuation Index Attenuation (dB)
0 0
1 0.05
2 0.10
3 0.15
4 0.20
... ...
Table 61 shows that the first column is the transmitter attenuation index. The second column shows the total transmitter attenuation in dB for
the corresponding index. Note that the attenuation step size for the adjacent index is 0.05dB. The third column is the control word to calculate
the analog attenuation (dB) shown in the fourth column. The equation for this calculation is:
Analog Attenuation (dB) = 20 × log
The 5th and 6th columns show the required digital attenuation in dB and linear domain respectively to achieve the total attenuation in the
second column. The last column stands for the digital attenuation control word to calculate the linear digital attenuation in the sixth column
based on the following algorithm:
If Digital Attenuation Control Word = 4095
12
Digital Attenuation = 4096/2
else,
Digital Attenuation = Digital Attenuation Control Word/2
Note only the third and the seventh columns are actually stored in memory. Other columns shown in
Read and write the table through the following API command, "adi_adrv9001_Tx_AttenuationTable_Read()" and "adi_adrv9001_Tx_Attenu-
ationTable_Write()". For more details about API functions, see the API Doxygen document.
Note that the table content is defined by the data structure "adi_adrv9001_TxAttenTableRow_t" as the following:
typedef struct adi_adrv9001_TxAttenTableRow{
uint16_t txAttenMult;
uint8_t txAttenHp;
uint8_t Reserve;} adi_adrv9001_TxAttenTableRow_t
where:
"txAttenMult" denotes the "Digital Attenuation Control Word" (in the range of 0 to 4095).
"txAttenHp" denotes the "Analog Attenuation Control Word" (in the range of 0 to 63).
Table 61 shows these.
Transmitter Attenuation Mode
There are four modes to control the transmitter attenuation block: bypass, SPI, GPIO, and closed-loop gain control (CLGC) modes. The API
command "adi_adrv9001_Tx_AttenuationMode_Set()" sets the transmitter attenuation mode.
Besides that, another API, "adi_adrv9001_Tx_Attenuation_Configure()" sets more configurations for the transmitter attenuation block, such
as the transmitter attenuation step size.
The enum "adi_adrv9001_TxAttenuationControlMode_e" defines four transmitter attenuation modes.
typedef enum adi_adrv9001_TxAttenuationControlMode
{
ADI_ADRV9001_TX_ATTENUATION_CONTROL_MODE_BYPASS = 0,
analog.com
Analog Attenuation Analog Attenuation
Control Word[5:0] (dB)
0 0.00
0 0.00
0 0.00
1 0.14
1 0.14
... ...
(1 − Analog Attenuation Control Word/64)
10
12
Digital Attenuation Digital Attenuation
(dB) (Linear)
0.00 1.00
0.05 0.9943
0.10 0.9886
0.01 1.00
0.06 0.9928
... ...
Table 61 are only for explanation.
ADRV9001
Digital Attenuation
Control Word[11:0]
4095
4072
4049
4090
4066
...
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