AD9957/PCBZ Analog Devices Inc, AD9957/PCBZ Datasheet - Page 17

• Manufacturer Part Number: AD9957/PCBZ
• Description: D/A Converter Evaluation Board
• Manufacturer: Analog Devices Inc
• Series: AgileRF™r

Specifications of AD9957/PCBZ

• Silicon Manufacturer: Analog Devices
• Application Sub Type: Direct Digital Synthesizer
• Kit Application Type: Clock & Timing
• Silicon Core Number: AD9957
• Kit Contents: Board
• Main Purpose: Timing: DDS Modulators
• Embedded: No
• Utilized Ic / Part: AD9957
• Primary Attributes: 14-Bit DAC, 32-Bit Tuning Word Width
• Secondary Attributes: 1GHz, Graphical User Interface
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

QUADRATURE MODULATION MODE
A block diagram of the AD9957 operating in QDUC mode is
shown in Figure 26; grayed items are inactive. The parallel input
accepts 18-bit I- and Q-words in time-interleaved fashion. That
is, an 18-bit I-word is followed by an 18-bit Q-word, then the
next 18-bit I-word, and so on. One 18-bit I-word and one 18-bit
Q-word together comprise one internal sample. The data assem-
bler and formatter de-interleave the I- and Q-words so that each
sample propagates along the internal data pathway in parallel
fashion. Both I and Q data paths are active; the parallel data
clock (PDCLK) serves to synchronize the input of I/Q data to
the AD9957.
TxENABLE
PDCLK
I/Q IN
FTW
18
PW
TIMING AND CONTROL
PROGRAMMING
PARALLEL DATA
REGISTERS
3
18
16
16
18
QS
Q
IS
I
SERIAL I/O
PORT
INTERNAL CLOCK TIMING AND CONTROL
Figure 26. Quadrature Modulation Mode
I Q
RAM
IS QS
Rev. B | Page 17 of 64
OSK
AD9957
cos (ωt+θ)
θ
ω
sin (ωt+θ)
CLOCK
CONTROL
DDS
POWER
DOWN
The PROFILE and I/O_UPDATE pins are also synchronous to
the PDCLK.
The DDS core provides a quadrature (sine and cosine) local
oscillator signal to the quadrature modulator, where the
interpolated I and Q samples are multiplied by the respective
phase of the carrier and summed together, producing a
quadrature modulated data stream. This data stream is routed
through the inverse sinc filter (optionally), and the output
scaling multiplier. Then it is applied to the 14-bit DAC to
produce the quadrature modulated analog output signal.
2
2
SYSCLK
DAC GAIN
PLL
÷2
8
OUTPUT
FACTOR
SCALE
8-BIT
AUX
DAC
14-BIT
DAC
DAC_RSET
IOUT
IOUT
REFCLK_OUT
REF_CLK
REF_CLK
XTAL_SEL
AD9957