Datasheet

AD9957 Data Sheet
Rev. C | Page 20 of 64
SINGLE TONE MODE
A block diagram of the AD9957 operating in single tone mode
is shown in Figure 29; grayed items are inactive. In this mode,
both I and Q data paths are disabled from the 18-bit parallel
data port up to, and including, the modulator. The internal
DDS core produces a single frequency signal based on the
programmed tuning word. The user may select either the
cosine or sine output of the DDS. The sinusoid at the DDS
output can be scaled using a 14-bit amplitude scale factor (ASF)
and optionally routed through the inverse sinc filter.
Single tone mode offers the output shift keying (OSK) function.
It provides the ability to ramp the amplitude scale factor between
zero and an arbitrary preset value over a programmable time
interval.
06384-009
PDCLK
I/Q IN
EXT_PWR_DWN
DAC_RSET
IOUT
IOUT
TxENABLE
FTW
PW
DAC GAIN
θ
INVERSE
SINC
FILTER
CLOCK
FTW
PW
8
SYSCLK
PLL
÷2
CLOCK MODE
REF_CLK
REF_CLK
REFCLK_OUT
X
TAL_SEL
PARALLEL DATA
TIMING AND CONTROL
AD9957
ω
cos (ωt+θ)
sin (ωt+θ)
SYNC_OUT
SYNC_IN
PLL_LOCK
PLL_LOOP_FILTER
MASTER_RESET
2
2
CCI_OVFL
OSK
DDS
AUX
DAC
8-BIT
POWER
DOWN
CONTROL
RT
RAM
PROFILE
SERIAL I/O
PORT
I/O_UPDATE
PROGRAMMING
REGISTERS
3
I Q IS QS
10
DATA ASSEMBLER AND FORMATTER
I
Q
IS
QS
BLACKFIN INTERFACE
18
18
16
16
HALF-BAND
FILTERS (4×)
INVERSE
CCI
CCI
(1× TO 63×)
HALF-BAND
FILTERS (4×)
INVERSE
CCI
CCI
(1× TO 63×)
OSK
INTERNAL CLOCK TIMING AND CONTROL
DAC
14-BIT
OUTPUT
SCALE
FACTOR
SDIO
CS
I/O_RESET
SCLK
SDO
Figure 29. Single Tone Mode