Gain Control Modes - Analog Devices ADRV9001 User Manual

Reference Manual
RECEIVER GAIN CONTROL
The receive channel can also operate as an observation channel (ORx), as discussed in
a case, a different gain table is used. It provides 0 dB to 30 dB attenuation in 5 dB step size. The gain index is from 2 to 14. Gain index 14
provides 0 dB attenuation, then the next two indexes (both 13 and 12) provide 5 dB attenuation. The last two indexes (both 3 and 2) provide
30 dB attenuation. The digital gain specified in the gain table is only used for gain correction. In addition, only manual gain control is supported.
Note that the ADRV9001 also uses the ORx gain table internally for initial and tracking calibrations (see
Receiver Signal Chain Calibrations) so it should not be modified by user.

GAIN CONTROL MODES

Select the gain control mode through the API function adi_adrv9001_Rx_GainControl_Mode_Set() for a specified channel. For more details,
refer to the API Doxygen document. adi_adrv9001_RxGainControlMode_e is an enum to select the gain mode.
options.
Table 70. Definition of adi_adrv9001_RxGainControlMode_e
ENUM
ADI_ADRV9001_RX_GAIN_CONTROL_MODE_SPI
ADI_ADRV9001_RX_GAIN_CONTROL_MODE_PIN
ADI_ADRV9001_RX_GAIN_CONTROL_MODE_AUTO
The adi_common_ChannelNumber_e enum indicates the receiver channel to use
Table 71. Definition of adi_common_ChannelNumber_e
ENUM
ADI_CHANNEL_1
ADI_CHANNEL_2
Automatic Gain Control (AGC)
In the AGC mode, a built-in state machine automatically controls the gain based on the user-defined configuration. The AGC is configured to
one of two modes:
Peak detect mode, where only the peak detectors are used to make gain changes.
►
Peak/Power detect mode, where information from both the power detector and peak detectors are used jointly to make gain changes.
►
Peak Detect Mode
In this mode, only the peak detectors are used to inform the AGC to make gain changes. This section explains the basic premise of the
operation, while the subsequent sections cover the more explicit details of configuring the peak detectors.
The APD and HB detector both have a high threshold and a low threshold, apdHighTresh, apdLowThresh, hbHighTresh, and hbUnderRange-
HighThresh, respectively. These levels are user programmable, as well as the number of times to exceed a threshold to flag an overrange
condition.
The high thresholds are used as limits on the incoming signal level and are principally set based on the maximum input of the ADC. When an
overrange condition occurs, the AGC reduces the gain (gain attack). The low thresholds are used as lower limits on the signal level. When an
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Figure 151. AGPIO Control of an External Gain Element to Rx1
Gain Mode
Manual Gain Control SPI Mode
Manual Gain Control PIN Mode
Automatic Gain Control Mode
Rx Channel
Rx1
Rx2
Receiver/Observation Receiver Signal
Transmitter/Receiver/Observation
Table 70
ADRV9001
Chain. In such
shows the possible
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