Analog Devices ADRV9002 User Manual

UG-1828 Preliminary Technical Data
Rev. PrC | Page 168 of 338
The HB detector has a number of programmable thresholds. Some of these thresholds are only used in the fast recovery mode of the peak
detect AGC configuration, as summarized in Table 68.
Table 68. HB Overload Thresholds
HB Threshold Usage
hbHighThresh Used for gain attack in both peak and peak/power detect AGC modes.
hbUnderRangeHighThresh Used for gain recovery in peak detect AGC mode. In peak/power detect AGC mode it is used to prevent
overloads during gain recovery.
hbUnderRangeMidThresh Used only when the fast recovery option of the peak detect AGC mode is being used.
hbUnderRangeLowThresh Used only when the fast recovery option of the peak detect AGC mode is being used.
For more details of how these thresholds are used by the AGC, refer to the relevant sections in this document.
The thresholds are related to an ADC dBFS value using the following equations:
Each threshold has an associated counter such that an over-range condition is not flagged until the threshold has been exceeded this
amount of times in a gain update period.
Table 69. Counters for HB Overrange and Underrange Conditions
HB Threshold Counter
hbHighThresh hbUpperThreshPeakExceededCount
hbUnderRangeHighThresh hbUnderRangeHighThreshExceededCount
hbUnderRangeMidThresh hbUnderRangeMidThreshExceededCount
hbUnderRangeLowThresh hbUnderRangeLowThreshExceededCount
In AGC mode, the HB peak detector has programmable gain attack and gain recovery step sizes.
Table 70. HB Attack and Recovery Step Sizes
Gain Change Step Size
Gain Attack
hbGainStepAttack
Gain Recovery (hbUnderRangeHighThresh) hbGainStepHighRecovery
Gain Recovery (hbUnderRangeMidThresh) hbGainStepMidRecovery
Gain Recovery (hbUnderRangeLowThresh) hbGainStepLowRecovery
The HB peak detector is held in reset for a configurable amount of time following a gain change to ensure that the receiver path is settled
at the new gain setting.
Power Detector
The power measurement block measures the RMS power of the incoming signal at the output of HB Filtering block. The number of
samples that are used in the power measurement calculation is configurable using the powerMeasurementDuration API parameter:
Power Meas Duration (Rx Sample Clocks) = 8 × 2
powerMeasurementDuration
where Rx Sample Clocks is the number of clocks at the power measurement location.
It is important that this duration not exceed the gain update counter. The gain update counter resets the power measurement block and
therefore a valid power measurement must be available before this event. In the case of multiple power measurements occurring in a gain
update period, the AGC will use the last fully completed power measurement, any partial measurements being discarded.
Note currently, only inner thresholds of power detector are utilized. The inner thresholds defined in API are related to an ADC dBFS
value using the following equations:
underRangeHighPowerThresh = -(underRangeHighPowerThresh _dBFS + 6)
overRangeLowPowerThresh = -(overRangeLowPowerThresh_dBFS + 6)

Analog Devices ADRV9002 Specifications

General

Brand	Analog Devices
Model	ADRV9002
Category	Transceiver
Language	English