Datasheet
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B0041-01
y2
1, −1, 1, ...
DAC
Ch2
Ch1
RF
Processing
TRF3750
GC4116
GC5016
GC5316
DUC
DAC5687
CDC7005
y2
y2y2
1, −1, 1, ...
DUC
DUC
DUC
DAC
RF
Processing
Application Example: Complex IF to RF Conversion Radio
B0042-01
y2
DAC
I
Q
RF
Processing
TRF3750
DAC5687
CDC7005
y2
y2y2
DAC
NCO
CMIX
TRF3701
TRF3702
TRF3703
DAC5687
SLWS164E – FEBRUARY 2005 – REVISED SEPTEMBER 2006
Figure 77. System Diagram of a Dual-Channel Real IF Radio
The outputs of multiple DAC5687s can be phase synchronized for multiple antenna/beamforming applications.
An alternative to a real IF system is to use a complex IF DAC output with analog quadrature modulator, as
shown in Figure 78 . The same complex baseband input as the real IF system in Figure 76 is used. The
DAC5687 would be used to increase the data rate through interpolation and flexibly place the output signal using
the FMIX and/or CMIX blocks. Although the DAC5687 X4 mode is shown, any of the modes (X2, X4L, or X8)
would be appropriate.
Figure 78. Complex IF System Using the DAC5687 in X4L Mode
Instead of only using one DAC5687 output as for the real IF output, both DAC5687 outputs are used for a
complex IF Hilbert transform pair.
The DAC5687 outputs can be expressed as:
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