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參數(shù)資料
| 型號： | AD9852ASQ |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | XO, clock |
| 英文描述： | CMOS 300 MHz Complete-DDS |
| 中文描述： | PLL FREQUENCY SYNTHESIZER, 30 MHz, PQFP80 |
| 封裝： | MS-026-BEC, LQFP-80 |
| 文件頁數(shù)： | 21/42頁 |
| 文件大小： | 424K |
| 代理商： | AD9852ASQ |
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AD9852
–21–
REV. 0
20-BIT
RAMP RATE
CLOCK
48-BIT DELTA-
FREQUENCY
WORD
FREQUENCY
ACCUMULATOR
PHASE
ACCUMULATOR
OUT
ADDER
SYSTEM
CLOCK
CLR ACC2
CLR ACC1
FREQUENCY
TUNING
WORD 1
HOLD
Figure 44. FM Chirp Components
Basic FM Chirp Programming Steps
1. Program a start frequency into Frequency Tuning Word 1
(parallel register addresses 4–9 hex) hereafter called FTW1.
2. Program the frequency step resolution into the 48-bit,
twos
complement,
Delta Frequency Word (parallel register addresses
10–15 hex).
3. Program the rate of change (time at each frequency) into the
20-bit Ramp Rate Clock (parallel register addresses 1A–C).
4. When programming is complete, an I/O update pulse at Pin
20 will engage the program commands.
The necessity for a twos complement Delta Frequency Word is
to define the direction in which the FM chirp will move. If the
48-bit delta frequency word is negative (MSB is high), the
incremental frequency changes will be in a negative direction from
FTW1. If the 48-bit word is positive (MSB is low), the incre-
mental frequency changes will be in a positive direction.
F1
0
F
010 (RAMPED FSK)
F1
000 (DEFAULT)
0
MODE
TW1
DFW
RAMP RATE
Figure 43. Example of a Nonlinear Chirp
It is important to note that the FTW1 is only a starting point for
FM chirp. There is no built-in restraint requiring a return to
FTW1. Once the FM chirp has left FTW1 it is free to move
(under program control) within the Nyquist bandwidth (dc to
1/2 system clock).
Instant
return to FTW1 is easily achieved,
though, and this option is explained in the next few paragraphs.
Two control bits are available in the FM Chirp mode that will
allow practically instantaneous return to the beginning frequency,
FTW1, or to 0 Hz. First, CLR ACC1
bit, register address 1F
hex will, if set high, clear the 48-bit
frequency accumulator
(ACC1)
output
with a retriggerable one-shot pulse of one system clock
duration. The 48-bit Delta Frequency Word input to the accu-
mulator is unaffected by CLR ACC1 bit. If the CLR ACC1 bit
is left high, a one-shot pulse will be delivered to the Frequency
Accumulator (ACC1) on every rising edge of the I/O Update
Clock. The effect is to interrupt the current chirp, reset the
frequency back to FTW1, and continue the chirp at the previously
programmed rate and direction. Clearing the Frequency
Accumulator in the chirp mode is illustrated in Figure 45. Not
shown in the diagram is the I/O update signal, which is either
user-supplied or internally generated. A discussion of I/O Update
is presented elsewhere in this data sheet.
Next, CLR ACC2
control bit (register address 1F hex) is available to
clear both the
frequency accumulator
(ACC1) and the
phase
accumulator
(ACC2). When this bit is set high, the output of the
phase accumulator will result in 0 Hz output from the DDS. As
long as this bit is set high, the frequency and phase accumulators
will be cleared, resulting in 0 Hz output. To return to previous
DDS operation, CLR ACC2 must be set to logic low.
This bit is
useful in generating pulsed FM.
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相關(guān)代理商/技術(shù)參數(shù) |
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| AD9852ASQZ | 制造商:Analog Devices 功能描述:Direct Digital Synthesizer 300MHz 2-DAC 12-Bit Parallel/Serial 80-Pin LQFP |
| AD9852AST | 制造商:Analog Devices 功能描述:Direct Digital Synthesizer 300MHz 2-DAC 12-Bit Parallel/Serial 80-Pin LQFP Tray 制造商:Rochester Electronics LLC 功能描述:200 MHZ C-DDS SYNTHESIZER - Bulk 制造商:Analog Devices 功能描述:IC DDS SYNTHESIZER |
| AD9852ASTZ | 功能描述:IC DDS SYNTHESIZER CMOS 80-LQFP 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) |
| AD9852ASTZ | 制造商:Analog Devices 功能描述:IC DDS 100MHZ LQFP-80 |
| AD9852ASTZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:CMOS 300 MSPS Complete DDS |
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