參數(shù)資料
型號(hào)： AD9957
廠商： Analog Devices, Inc.
英文描述： 1 GSPS Quadrature Digital Upconverter with 18-Bit IQ Data Path and 14-Bit DAC
中文描述： 1 GSPS的正交數(shù)字上變頻器與18位智商數(shù)據(jù)路徑和14位DAC
文件頁(yè)數(shù)： 39/60頁(yè)
文件大小： 840K
代理商： AD9957
AD9957
SYNCHRONIZATION OF MULTIPLE DEVICES
The internal clocks of the AD9957 provide the timing for the
propagation of data along the baseband signal processing path.
These internal clocks are derived from the internal system clock
(SYSCLK) and are all submultiples of the SYSCLK frequency.
The logic state of all of these clocks in aggregate during any
given SYSCLK cycle defines a unique clock state. The clock state
advances with each cycle of SYSCLK, but the sequence of clock
states is periodic. By definition, multiple devices are synchro-
nized when their clock states match and they transition between
states simultaneously. Clock synchronization allows the user to
asynchronously program multiple devices, but synchronously
activate the programming by applying a coincident I/O update
to all devices. It also allows multiple devices to operate in unison
when the parallel port is in use with either the QDUC or inter-
polating DAC mode (see Figure 57).
Rev. 0 | Page 39 of 60
The function of the synchronization logic in the AD9957 is to
force the internal clock generator to a predefined state coincident
with an external synchronization signal applied to the SYNC_IN
pins. If all devices are forced to the same clock state in synchro-
nization with the same external signal, then the devices are, by
definition, synchronized. Figure 54 is a block diagram of the
synchronization function. The synchronization logic is divided
into two independent blocks, a sync generator and a sync receiver,
both of which use the local SYSCLK signal for internal timing.
SYNC
GENERATOR
REF_CLK
5
SYSCLK
ICLOCKS
6
5
4
SYNC
RECEIVER
S
G
E
S
G
D
S
P
90
91
9
10
SYNC_OUT
REF_CLK
INPUT
CIRCUITRY
7
8
12
SYNC_IN
SYNC_SMP_ERR
SYNC
VALIDATION
DELAY
SYNC STATE
PRESET VALUE
SYNC
TIMING
VALIDATION
DISABLE
C
G
SETUP AND
HOLD VALIDATION
SYNC
RECEIVER
ENABLE
SYNC
RECEIVER
DELAY
0
INPUT DELAY
AND EDGE
DETECTION
Figure 54. Synchronization Circuit Block Diagram
The synchronization mechanism relies on the premise that the
REFCLK signal appearing at each device is edge aligned with all
others as a result of the external REFCLK distribution system
(see Figure 57).
The sync generator block is shown in Figure 55. It is activated
via the sync generator enable bit. It allows for one AD9957 in a
group to function as a master timing source with the remaining
devices slaved to the master.
SYSCLK
SYNC
GENERATOR
ENABLE
SYNC
GENERATOR
DELAY
SYNC
POLARITY
SYNC_OUT
0
1
D Q
R
PROGAMMABLE
DELAY
÷16
÷N
5
9
10
LVDS
DRIVER
0
Figure 55. Sync Generator
The sync generator produces a clock signal that appears at the
SYNC_OUT pins. This clock is delivered by an LVDS driver
and exhibits a 50% duty cycle. The clock has a fixed frequency
given by
N
f
f
SYSCLK
16
SYNCOUT
=
where
N
is 1 when the AD9957 is configured in the single tone
mode, but is equal to the programmed interpolation factor of
the CCI filter when configured in either the QDUC or
interpolating DAC mode.
The clock at the SYNC_OUT pins synchronizes with either the
rising or falling edge of the internal SYSCLK signal as determined
by the sync polarity bit. Because the SYNC_OUT signal is synchro-
nized with the internal SYSCLK of the master device, the master
device SYSCLK serves as the reference timing source for all slave
devices. The user can adjust the output delay of the SYNC_OUT
signal in steps of ~150 ps by programming the 5-bit sync gen-
erator delay word via the serial I/O port. The programmable
output delay facilitates added edge timing flexibility to the
overall synchronization mechanism.
The sync receiver block (shown in Figure 56) is activated via the
sync receiver enable bit. The sync receiver consists of three sub-
sections: the input delay and edge detection block, the internal
clock generator block, and the setup-and-hold validation block.
The clock generator block remains operational even when the
sync receiver is not enabled.
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參數(shù)描述
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AD9957BCPZ 制造商:Analog Devices 功能描述:GSPS QUADRATURE DIGITAL UPCONVERTER W/18-BIT IQ DATA PATH - Trays
AD9957BSVZ 功能描述:IC DDS 1GSPS 14BIT IQ 100TQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 直接數(shù)字合成 (DDS) 系列:- 產(chǎn)品變化通告:Product Discontinuance 27/Oct/2011 標(biāo)準(zhǔn)包裝:2,500 系列:- 分辨率（位）:10 b 主 fclk:25MHz 調(diào)節(jié)字寬（位）:32 b 電源電壓:2.97 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:帶卷 (TR)
AD9957BSVZ-REEL 功能描述:IC DDS 1GSPS 14BIT IQ 100TQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 直接數(shù)字合成 (DDS) 系列:- 產(chǎn)品變化通告:Product Discontinuance 27/Oct/2011 標(biāo)準(zhǔn)包裝:2,500 系列:- 分辨率（位）:10 b 主 fclk:25MHz 調(diào)節(jié)字寬（位）:32 b 電源電壓:2.97 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:帶卷 (TR)
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