TDD RX/Obs Sharing Mode - 2.6 English

Zynq UltraScale+ RFSoC RF Data Converter v2.6 Gen 1/2/3/DFE LogiCORE IP Product Guide (PG269)

Document ID
PG269
Release Date
2024-05-30
Version
2.6 English

In the TX time slot, some RX channels can be reused as TX observation channels for PA linearization. The observation channel, in general, requires a wider bandwidth than the RX channel; this results in different decimation factors and data rates between the RX and Obs configurations.

When enabling the TDD RX/Obs sharing mode in the IP configuration, there are two AXI4-Stream interfaces available for each RF-ADC channel. The decimation factor, output data rate, and FIFO configurations for each AXI4-Stream are preserved independently, and can be switched dynamically using PL inputs (tdd_obs). Note that the RX and Obs configurations share other function blocks in RF-ADC, such as the complex mixer/NCO, DSA, etc. For example, choose the same real/complex mode and the same NCO frequencies for both RX and Obs channels. The RX and Obs channels transmit data simultaneously, yet only the data from the currently configured channel is considered valid due to the compatibility of the data rate between the RFDC IP and the PL. The DSA value can vary when RF-ADC switches from one mode to another. You should set your desired DSA value each time through real time ports or RFdc API.

For RX/Obs shared channels, when DSA values are different for RX mode and Obs mode, user should set desired DSA value for each mode before or after switching from one mode to another, the real time DSA ports enable fast DSA values updating.

Note: The multi-tile synchronization (MTS) is valid for RX mode only and is not supported in Obs mode. The MTS keeps its states and will not be impacted when RX/Obs mode is switching.

Two PL clocks (AXIS_aclk, AXIS_obs_aclk) are available for different data rates.

The following diagram illustrates the TDD RX/Obs sharing mode.

Figure 1. TDD RX/Obs Sharing Mode

An example of the timing on the observation interface is shown in the following figure. When tdd_obs is Low the outputs are from the FIFO1 datapath. When tdd_obs is High the outputs are from the FIFO2 datapath. The switchover time is dependent on the settings in the RF-ADC digital datapath.

Figure 2. TDD RX/Obs Sharing Mode Timing