dac1628d1g25 NXP Semiconductors, dac1628d1g25 Datasheet - Page 25

• Manufacturer Part Number: dac1628d1g25
• Description: Dual 16-bit Dac Jesd204b Interface Up To 1.25 Gsps; X2, X4 And X8 Interpolating
• Manufacturer: NXP Semiconductors

NXP Semiconductors
DAC1628D1G25
Objective data sheet
10.7.3 Minus 3dB
10.8
10.9 DAC transfer function
Where:
The eight most significant bits of the NCO phase offset registers (PH_NCO[7:0];
see
In normal use, a full-scale pattern is also full-scale at the DAC output. Nevertheless, when
the I data and Q data come close to full-scale simultaneously, some clipping can occur.
The Minus 3dB function (bit MINUS_3DB of register DAC_OUT_CTRL; see
be used to reduce the 3 dB gain in the modulator. It retains a full-scale range at the DAC
output without added interferers.
A selectable FIR filter is incorporated to compensate the sinx / x effect caused by the
roll-off effect of the DAC. The coefficients are represented in
Table 13.
Remark: The transfer function of this features adds some gain to the signals and some
clipping can occur with a level of distortion in the output spectrum as result. Update the
digital gain accordingly to avoid this clipping.
The full-scale output current for each DAC is the sum of the two complementary current
outputs:
The output current of DAC A depends on the digital input data and the gain factor defined
by bits DAC_A_GAIN[11:0] of register DAC_A_DGAIN_MSB (see
I
I
Lower
H(1)
H(2)
H(3)
H(4)
H(5)
Inverse sinx / x
IOUTAP
IOUTAN
•
•
•
•
M is the value set in the bits FREQNCO[39:0] of the NCO frequency registers
(see
f
Table
I
I
s
OA fs
OB fs 
is the DAC clock sampling frequency
 

=
=
Table
20) can set the phase of the NCO low power.

Inversion filter coefficients
I
I
=
OA fs
=
OA fs
I
IOUTAP
I
 
 
21).
IOUTBP
All information provided in this document is subject to legal disclaimers.



----------------------------------------------- -


DAC_A_DGAIN
1
Rev. 1.1 — 10 October 2011
+
–
+
I

----------------------------------------------- -
IOUTAN
I
DAC_A_DGAIN
IOUTBN
1024
Upper
H(9)
H(8)
H(7)
H(6)
-
1024
Dual 16-bit DAC: JESD204B interface; up to 1.25 Gsps
First interpolation filter




-------------------


DATA
65535



-------------------

DATA
65535








DAC1628D1G25
Value
+1
4
+13
51
+610
Table
Table
13.
© NXP B.V. 2011. All rights reserved.
23).
Table
24) can
25 of 133
(3)
(4)