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DAC1627D1G25 View Datasheet(PDF) - NXP Semiconductors.

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DAC1627D1G25 Datasheet PDF : 69 Pages
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NXP Semiconductors
DAC1627D1G25
Dual 16-bit DAC: up to 1.25 Gsps; x2, x4 and x8 interpolating
10.9.4 Minus 3dB
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 Table 38) can
be used to reduce the 3 dB gain in the modulator. It retains a full-scale range at the DAC
output without added interferers.
10.10 Inverse sinx / x
A selectable FIR filter is incorporated to compensate the sinx / x effect caused by the
roll-off effect of the DAC. This filter introduces a loss of 3.4 dB at DC. The coefficients are
represented in Table 17.
Table 17.
Lower
H(1)
H(2)
H(3)
H(4)
H(5)
Inversion filter coefficients
First interpolation filter
Upper
H(9)
H(8)
H(7)
H(6)
-
Value
+1
4
+13
51
+610
10.11 DAC transfer function
The full-scale output current for each DAC is the sum of the two complementary current
outputs:
IOA(fs) = IIOUTAP + IIOUTAN
IOB(fs)) = IIOUTBP + IIOUTBN
The output current of DAC A depends on the digital input data and the gain factor defined
by bits DAC_A_DGAIN[7:0] of register DAC_A_DGAIN_LSB (see Table 34) and bits
DAC_A_DGAIN[11:8] of register DAC_A_DGAIN_MSB (see Table 35).
IIOUTAP
=
IOA(fs
)
×
(---D-----A----C----A----D-----G----A----I---N----)-
1024
×
(---(--D6---5-A--5---T3---A5----)--)-⎠⎞
(3)
IIOUTAN
=
IO
A(fs
)
×
⎝⎛1
(---D-----A----C----A----D-----G----A----I---N----)-
1024
×
(---(--D6---5-A--5---T3---A5----)--)-⎠⎞
(4)
The output current of DAC B depends on the digital input data and the gain factor defined
by bits DAC_B_DGAIN[7:0] of register DAC_B_DGAIN_LSB (see Table 36) and bits
DAC_B_DGAIN[11:8] of register DAC_B_DGAIN_MSB (see Table 37).
IIOUTBP
=
IOB
(fs)
×
(---D-----A----C----B----D-----G----A----I---N----)-
1024
×
(---(--D6---5-A--5---T3---A5----)--)-⎠⎞
(5)
IIOUTBN
=
IO
B(fs
)
×
⎝⎛1
(---D-----A----C----B----D-----G----A----I---N----)-
1024
×
(---(--D6---5-A--5---T3---A5----)--)-⎠⎞
(6)
DAC1627D1G25
Objective data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 29 April 2011
© NXP B.V. 2011. All rights reserved.
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