AD9081 Digital Up Converters
The AD9081 has two sets of digital up converters (DUC), the coarse (CDUC) and fine (FDUC). These are used to both interpolate and move signals using the NCOs. They also can be used to phase shift and apply gain to the input signal.
The CDUCs and FDUC are almost identical except for their available interpolations, allowable rates, and count. There are two CDUCs per DAC pair and four FDUCs per DAC pair. In the data pipeline, data from the input will be passed through the FDUCs, or bypass the FDUCs, then routed through a mux into the CDUCs, which can also be bypassed.
Top-Level Control
The CDUC and FDUC interpolations are controlled by MainDataPathInterpolation and ChannelizerPathInterpolation respectively.
MainDataPathInterpolation Main Data Path Interpolation
Specify the decimation in the main data path which can be
[1,2,3,4,6]
ChannelizerPathInterpolation Channelizer Path Interpolation
Specify the decimation in the channelizer path which can be
[1,2,3,4,6,8,12,16,24]
Muxing
The FDUC quads share a common full crossbar to the pairs of upstream CDUCs connected to them. This is represented by a single summing crossbar that limits routes to the halves of AD9081. This crossbar or mux is controlled by the Crossbar8x8Mux and will constrain all the mappings.
Crossbar8x8Mux Crossbar 8x8 Mux
Logical 4x8 array of for MainDataPath input summers. Each row
corresponds to each summmer [1-4] and each column corresponds
to an input Channelizer path 1-8]. Set indexes to true to
enable a given path to be added into summer's output.
The 8x8 summing crossbar can sum any channels within the FDUC quads (FDUC0->FDUC3 and FDUC4->FDUC7). This is controlled by the columns of Crossbar8x8Mux, where each true row in a given column is feed into the individual summers feeding the inputs to the CDUCs. Below is an example of summing FDUC0,FDUC1,FDUC3 to CDDC0 and FDUC4,FDUC5 to CDDC2:
tx = adi.sim.AD9081.Tx;
tx.Crossbar8x8Mux = [...
1,0,0,0,0,0,0,0;...FDUC0->CDUC0
0,1,0,0,0,0,0,0;...FDUC1->CDUC1
0,0,1,0,0,0,0,0;...FDUC2->CDUC2
0,0,0,1,0,0,0,0]; %FDUC3->CDUC3
NCO Frequency and Phase
Once the NCOs are enabled the frequencies and phases of the NCOs can be controlled individually. This is done through the CDUCNCOFrequencies, FDUCNCOFrequencies, CDUCNCOPhases, and FDUCNCOPhases. The frequencies will be limited based on the rate going into the NCO at that stage.