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14-Bit, 160 MSPS TxDAC+
with 2× Interpolation Filter
AD9772A
Rev. C
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FEATURES
Single 3.1 V to 3.5 V supply
14-bit DAC resolution and input data width
160 MSPS input data rate
67.5 MHz reconstruction pass band @ 160 MSPS
74 dBc SFDR @ 25 MHz
2× interpolation filter with high- or low-pass response
73 dB image rejection with 0.005 dB pass-band ripple
Zero-stuffing option for enhanced direct IF performance
Internal 2×/4× clock multiplier
250 mW power dissipation; 13 mW with power-down mode
48-lead LQFP package
APPLICATIONS
Communication transmit channel
W-CDMA base stations, multicarrier base stations,
direct IF synthesis, wideband cable systems
Instrumentation
FUNCTIONAL BLOCK DIAGRAM
14-BIT DAC
2× FIR
INTER-
POLATION
FILTER
EDGE-
TRIGGERED
LATCHES
CLOCK DISTRIBUTION
AND MODE SELECT
MUX
CONTROL
FILTER
CONTROL
1×/2×
2×/4×
1×
PLL CLOCK
MULTIPLIER
1.2V REFERENCE
AND CONTROL AMP
AD9772A
CLKCOM CLKVDD MOD0 MOD1 RESET PLLLOCK DIV0 DIV1
CLK+
CLK–
DATA
INPUTS
(DB13 TO
DB0)
SLEEP
DCOM DVDD
ACOM AVDD
REFLO
PLLCOM
LPF
PLLVDD
IOUTA
IOUTB
REFIO
FSADJ
ZERO-
STUFF
MUX
0
2253-
001
Figure 1.
GENERAL DESCRIPTION
The AD9772A is a single-supply, oversampling, 14-bit digital-
to-analog converter (DAC) optimized for baseband or IF
waveform reconstruction applications requiring exceptional
dynamic range. Manufactured on an advanced CMOS process,
it integrates a complete, low distortion 14-bit DAC with a 2×
digital interpolation filter and clock multiplier. The on-chip PLL
clock multiplier provides all the necessary clocks for the digital
filter and the 14-bit DAC. A flexible differential clock input
allows for a single-ended or differential clock driver for
optimum jitter performance.
For baseband applications, the 2× digital interpolation filter
provides a low-pass response, thus providing as much as a
threefold reduction in the complexity of the analog reconstruc-
tion filter. It does so by multiplying the input data rate by a
factor of 2 while suppressing the original upper in-band image
by more than 73 dB. For direct IF applications, the 2× digital
interpolation filter response can be reconfigured to select the
upper in-band image (that is, the high-pass response) while
suppressing the original baseband image. To increase the signal
level of the higher IF images and their pass-band flatness in
direct IF applications, the AD9772A also features a zero-stuffing
option in which the data following the 2× interpolation filter is
upsampled by a factor of 2 by inserting midscale data samples.
The AD9772A can reconstruct full-scale waveforms with band-
widths of up to 67.5 MHz while operating at an input data rate
of 160 MSPS. The 14-bit DAC provides differential current
outputs to support differential or single-ended applications.
A segmented current source architecture is combined with a
proprietary switching technique to reduce spurious components
and enhance dynamic performance. Matching between the two
current outputs ensures enhanced dynamic performance in a
differential output configuration. The differential current
outputs can be fed into a transformer or a differential op amp
topology to obtain a single-ended output voltage using an
appropriate resistive load.
The on-chip band gap reference and control amplifier are con-
figured for maximum accuracy and flexibility. The AD9772A
can be driven by the on-chip reference or by a variety of
external reference voltages. The full-scale current of the
AD9772A can be adjusted over a 2 mA to 20 mA range, thus
providing additional gain-ranging capabilities.
The AD9772A is available in a 48-lead LQFP package and is
specified for operation over the industrial temperature range of
–40°C to +85°C.