Tx Power Monitor Gain Control - Analog Devices AD9361 Reference Manual

UG-570

Tx POWER MONITOR GAIN CONTROL

TPM total gain comprises of two gains, front-end gain (Tx Mon
Gain) and receive low pass filter gain (G
gain is set by Tx Mon 1 Config and Tx Mon 2 Config registers
(Register 0x070 [D1:D0] and Register 0x071 [D1:D0],
respectively). Tx Mon TIA Gain values are shown in Table 41. In
addition to the two gains, Table 41 also includes minimum and
maximum TPM input signal levels and associated SNR.
Figure 31 shows a block diagram of the TPM signal chain. Note
that the local oscillator signal used to downconvert the TPM
input signal is Tx LO.
Table 41. TPM Gain and Dynamic Range
Tx Mon TIA Gain[1:0]
00
01
10
11
1 Bandwidth used for SNR calculation is 10 MHz.
). TPM front-end
BBF
TX_MON1
OR
TX_MON2
TX MON GAIN
0dB, 6dB, 9.5dB
Figure 31. TPM Gain Distribution
Tx Mon TIA Gain (dB)
Open
0
6
9.5
Rev. A
Receive low-pass filter gain, G
Mon Low Gain and Tx Mon High Gain (Register 0x067
[D4:D0] and Register 0x068 [D4:D0], respectively). These
values set the receive low-pass filter gain index in the 0 dB to
24 dB range. TPM gain mode, low or high is determined by a
threshold in Tx Atten Threshold register (Register 0x078
[D7:D0]). If the Tx Attenuation value (Register 0x073 and
Register 0x074) is equal to or less than the threshold the low
gain index value is used and if the value is greater than the
threshold the high gain index is used in the receive path.
Transimpedance amplifier (TIA) gain is automatically set high
or low by the AD9361. Tx RSSI1 and Tx RSSI2 values in
Register 0x06B, Register 0x06C, and Register 0x06D are
compensated for gain changes.
LO
I
BBF
BBF
LO
Q
G
BBF
0dB TO 30dB
GBBF (dB) Pin (dBm)
max
-- --
-- --
0 4
30 −25.7
0 −2.2
30 −31.7
0 −5.7
30 −35.2
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AD9361 Reference Manual
, is set by register values Tx
BBF
ADC
ADC
Pin (dBm)
min
--
--
−62.7
−70.1
−68.6
−75.8
−72.1
−78.9
SNR (dB) 1
--
--
67
44
67
44
66
44