Datasheet

DAC1405D750 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 5 — 31 January 2012 33 of 43
NXP Semiconductors
DAC1405D750
Dual 14-bit DAC, up to 750 Msps; 4 and 8 interpolating
The DAC1405D750 differential outputs can operate up to 2 V
o(p-p)
. In this configuration, it
is recommended to connect the center tap of the transformer to a 62  resistor connected
to the 3.3 V analog power supply, in order to adjust the DC common-mode to
approximately 2.7 V (see Figure 14
).
10.14.2 DC interface to an Analog Quadrature Modulator (AQM)
When the system operation requires to keep the DC component of the spectrum, the
DAC1405D750 can use a DC interface to connect to an AQM. In this case, the offset
compensation for LO cancellation can be made with the use of the digital offset control in
the DAC.
Figure 15
provides an example of a connection to an AQM with a 1.7 V
I(cm)
common-mode input level.
Fig 14. 2 V
o(p-p)
differential output with transformer
001aaj818
50 Ω
100 Ω
100 Ω
IOUTnP/IOUTnN; V
o(cm)
= 2.7 V; V
o(dif)(p-p)
= 2 V
IOUTnP
IOUTnN
0 mA to 20 mA
4:1
0 mA to 20 mA
V
DDA(3V3)
62 Ω
V
DDA(3V3)
V
DDA(3V3)
Fig 15. An example of a DC interface to a 1.7 V
I(cm)
AQM
001aaj541
51.1 Ω
51.1 Ω
442 Ω
442 Ω
V
DDA(3V3)
IOUTnP
IOUTnN
0 mA to 20 mA
BBP
(1)
IOUTnP/IOUTnN; V
o(cm)
= 2.67 V; V
o(dif)(p-p)
= 1.98 V
(2)
BBP/BBN; V
i(cm)
= 1.7 V; V
i(dif)(p-p)
= 1.26 V
BBN
AQM (V
i(cm)
= 1.7 V)
768 Ω 768 Ω
(1) (2)