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參數資料
| 型號： | AD9709AST |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | DAC |
| 英文描述： | RES 0.01 OHM MAX 25 AMP AXIAL |
| 中文描述： | PARALLEL, 8 BITS INPUT LOADING, 0.035 us SETTLING TIME, 8-BIT DAC, PQFP48 |
| 封裝： | PLASTIC, LQFP-48 |
| 文件頁數： | 17/27頁 |
| 文件大小： | 466K |
| 代理商： | AD9709AST |
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REV. 0
AD9709
–17–
CDMA
Carrier Division Multiple Access, or CDMA, is an air transmit/
receive scheme where the signal in the transmit path is modulated
with a pseudorandom digital code (sometimes referred to as the
spreading code). The effect of this is to spread the transmitted
signal across a wide spectrum. Similar to a DMT waveform, a
CDMA waveform containing multiple subscribers can be char-
acterized as having a high peak to average ratio (i.e., crest factor),
thus demanding highly linear components in the transmit signal
path. The bandwidth of the spectrum is defined by the CDMA
standard being used, and in operation is implemented by using
a spreading code with particular characteristics.
Distortion in the transmit path can lead to power being trans-
mitted out of the defined band. The ratio of power transmitted
in-band to out-of-band is often referred to as Adjacent Channel
Power (ACP). This is a regulatory issue due to the possibility
of interference with other signals being transmitted by air.
Regulatory bodies define a spectral mask outside of the transmit
band, and the ACP must fall under this mask. If distortion in
the transmit path causes the ACP to be above the spectral mask,
then filtering, or different component selection is needed to
meet the mask requirements.
Figure 42 shows the AD9709/AD8346 application circuit of
Figure 41 reconstructing a wideband, or W-CDMA test vector
with a bandwith of 8 MHz, centered at 2.4 GHz and being
sampled at 62.5 MHz. The IF frequency at the DAC output
is 15.625 MHz. ACPR for the given test vector is measured
at greater than 54 dB.
FREQUENCY
CENTER 2.4GHz 3MHz SPAN 30MHz
cu1
c11
–
130
–
120
–
110
–
100
–
90
–
80
–
70
–
60
–
50
–
40
–
30
d
1
C2
C0
c11
Figure 42. CDMA Signal, 8 M Chips Sampled at 65 MSPS,
Recreated at 2.4 GHz, Adjacent Channel Power > 54 dBm
Figure 43 shows an example of the AD9709 used in a W-CDMA
transmitter application using the AD6122 CDMA 3V IF sub-
system. The AD6122 has functions, such as external gain
control and low-distortion characteristics, needed for the
superior Adjacent Channel Power (ACP) requirements of
W-CDMA.
(
“
Q DAC
”
)
IOUTA
QOUTA
QOUTB
DCOM
FSADJ2
REFIO
SLEEP
R
1.9k
0.1 F
CLK2
Q DATA
INPUT
I DATA
INPUT
DVDD
AVDD
500
50
500
500
IIPP
IIPN
IIQP
IIQN
AD6122
CLK1
FSADJ1
R
SET1
2k
R
CAL
220
500
50
DAC
LATCH
DAC
(
“
I DAC
”
)
INPUT
LATCHES
WRT1
WRT2
ACOM
AD9709
U1
U2
LOIPP
LOIPN
2
PHASE
SPLITTER
REFIN
VGAIN
GAIN
CONTROL
TXOPP
TXOPN
GAIN
CONTROL
SCALE
FACTOR
TEMPERATURE
COMPENSATION
MODOPN
MODOPP
V
CC
V
CC
3V
500
500
IOUTB
INPUT
LATCHES
500
50
500
50
DAC
LATCH
DAC
634
Figure 43. CDMA Transmit Application Using AD9709 and AD6122
相關PDF資料 |
PDF描述 |
|---|---|
| AD9709-EB | 8-Bit, 125 MSPS Dual TxDAC D/A Converter |
| AD9712B | RES,0.0,0.25W,METAL FILM,0% |
| AD9712BAN | RES,0.0,0.25W,METAL FILM,0% |
| AD9712BAP | TEST POINT, WHITE, 0.040 HOLE, 0.062 PCB |
| AD9712BBN | POWER JACK, 250V,2 COND. FEMALE,2.1MM |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD9709ASTRL | 制造商:Analog Devices 功能描述:DAC 2-CH Segment 8-bit 48-Pin LQFP T/R 制造商:Rochester Electronics LLC 功能描述:8-BIT 125 MSPS DUAL TXDAC+ D/A CONVERTER - Tape and Reel |
| AD9709ASTZ | 功能描述:IC DAC 8BIT DUAL 125MSPS 48-LQFP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 數模轉換器 系列:TxDAC+® 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:50 系列:- 設置時間:4µs 位數:12 數據接口:串行 轉換器數目:2 電壓電源:單電源 功率耗散（最大）:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應商設備封裝:8-uMAX 包裝:管件 輸出數目和類型:2 電壓，單極 采樣率（每秒）:* 產品目錄頁面:1398 (CN2011-ZH PDF) |
| AD9709ASTZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:8-Bit, 125 MSPS, Dual TxDAC Digital-to-Analog Converter |
| AD9709ASTZKL1 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| AD9709ASTZRL | 功能描述:IC DAC 8BIT DUAL 125MSPS 48LQFP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 數模轉換器 系列:TxDAC+® 產品培訓模塊:LTC263x 12-, 10-, and 8-Bit VOUT DAC Family 特色產品:LTC2636 - Octal 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C Reference 標準包裝:91 系列:- 設置時間:4µs 位數:10 數據接口:MICROWIRE?，串行，SPI? 轉換器數目:8 電壓電源:單電源 功率耗散（最大）:2.7mW 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-WFDFN 裸露焊盤 供應商設備封裝:14-DFN-EP（4x3） 包裝:管件 輸出數目和類型:8 電壓，單極 采樣率（每秒）:* |
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