AD9957/PCBZ Analog Devices Inc, AD9957/PCBZ Datasheet - Page 22

• 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

AD9957
INPUT DATA ASSEMBLER
The input to the AD9957 is an 18-bit parallel data port in
QDUC mode or interpolating DAC mode. In BFI mode, it
operates as a dual serial data port.
In QDUC mode, it is assumed that two consecutive 18-bit
words represent the real (I) and imaginary (Q) parts of a
complex number of the form, I + jQ. The 18-bit words are
supplied to the input of the AD9957 at a rate of
where:
f
sample rate of the DAC.
R (for all of the PDCLK equations in this section) is the
interpolation factor of the programmable interpolation filter.
SYSCLK
f
(for all of the PDCLK equations in this section) is the
PDCLK
TxENABLE
TxENABLE
D<17:0>
D<17:0>
PDCLK
PDCLK
TxENABLE
Q DATA
=
PDCLK
I DATA
f
SYSCLK
2
R
Q
I
0
0
for QDUC mode
Q
I
1
1
t
t
DS
DS
t
t
DS
DS
Q
I
2
2
Figure 31. 18-Bit Parallel Port Timing Diagram—Quadrature Modulation Mode
I
I
0
0
Figure 30. 18-Bit Parallel Port Timing Diagram—Interpolating DAC Mode
t
t
DH
DH
Q
I
3
3
Figure 32. Dual Serial I/Q Bit Stream Timing Diagram, BFI Mode
Q
I
4
4
Q
I
1
Q
0
I
5
5
Q
I
6
6
Rev. B | Page 22 of 64
Q
I
I
I
7
2
1
7
Q
I
8
8
When the PDCLK rate control bit is active in QDUC mode,
however, the frequency of PDCLK becomes
In the interpolating DAC mode, the rate of PDCLK is the same
as QDUC mode with the PDCLK rate control bit active, that is,
In BFI mode, the 18-bit parallel input converts to a dual serial
input that is, one pin is assigned as the serial input for the I-words
and one pin is assigned as the serial input for the Q-words. The
other 16 pins are not used. Furthermore, each I- and Q-word
has a 16-bit resolution. f
streams and is given by
Q
I
9
9
Q
I
3
1
f
f
f
Q
PDCLK
PDCLK
PDCLK
I
10
10
Q
=
=
=
I
11
11
f
f
f
SYSCLK
SYSCLK
SYSCLK
4
4
R
Q
R
R
I
12
12
with PDCLK rate control active
for interpolating DAC mode
for BFI mode
Q
PDCLK
I
13
13
I
is the bit rate of the I- and Q-data
K – 1
Q
I
I
14
N
14
Q
I
15
15
t
t
DH
DH
Q
I
16n – 1
16n – 1
Q
I
K
N