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參數(shù)資料
| 型號(hào)： | AD9260EB |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | High-Speed Oversampling CMOS ADC with 16-Bit Resolution at a 2.5 MHz Output Word Rate |
| 中文描述： | 高速16位分辨率在2.5 MHz的輸出字速率采樣的CMOS模數(shù)轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 20/36頁(yè) |
| 文件大?。?/td> | 572K |
| 代理商： | AD9260EB |
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AD9260
–20–
REV. B
THEORY OF OPERATION
The AD9260 utilizes a new analog-to-digital converter architec-
ture to combine sigma-delta techniques with a high-speed,
pipelined A/D converter. This topology allows the AD9260 to
offer the high dynamic range associated with sigma-delta con-
verters while maintaining very wide input signal bandwidth
(1.25 MHz) at a very modest 8
×
oversampling ratio. Figure 53
provides a block diagram of the AD9260. The differential
analog input is fed into a second order, multibit sigma-delta
modulator. This modulator features a 5-bit flash quantizer and
5-bit feedback. In addition, a 12-bit pipelined A/D quantizes
the input to the 5-bit flash to greater accuracy. A special digital
modulation loop combines the output of the 12-bit pipelined
A/D with the delayed output of the 5-bit flash to produce the
equivalent response of a second order loop with a 12-bit
quantizer and 12-bit feedback. The combination of a second
order loop and multibit feedback provides inherent stability:
the AD9260 is not prone to idle tones or full-scale idiosyncra-
cies sometimes associated with higher order single bit sigma-
delta modulators.
The output of this 12-bit modulator is fed into the digital deci-
mation filter. The voltage level on the MODE pin establishes
the configuration for the digital filter. The user may bring the
data out undecimated (at the clock rate), or at a decimation
factor of 2
×
, 4
×
, or a full 8
×
. The spectra for these four cases
are shown in Figures 5, 6, 7 and 8, all for a 100 kHz full-scale
input and 20 MHz clock. The spectra of the undecimated
output clearly shows the second order shaping characteristic of
the quantization noise as it rises at frequencies above 1.25 MHz.
The on-chip decimation filter provides excellent stopband rejec-
tion to suppress any stray input signal between 1.25 MHz and
18.75 MHz, substantially easing the requirements on any anti-
aliasing filter for the analog input path. The decimation filters
are integrated with symmetric FIR filter structures, providing a
linear phase response and excellent passband flatness.
The digital output driver register of the AD9260 features both
READ and CHIP SELECT pins to allow easy interfacing. The
digital supply of the AD9260 is designed to operate over a
2.7 V to 5.25 V supply range, though 3 V supplies are recom-
mended to minimize digital noise on the board. A DATA
AVAILABLE pin allows the user to easily synchronize to the
converter
’
s decimated output data rate. OUT-OF-RANGE
(OTR) indication is given for an overflow in the pipelined A/D
converter or digital filters. A RESETB function is provided to
synchronize the converter
’
s decimated data and clear any over-
flow condition in the analog integrators.
An on-chip reference and reference buffer are included on the
AD9260. The reference can be configured in either a 2.5 V
mode (providing a 4 V pk-pk differential input full scale), a 1 V
mode (providing a 1.6 V pk-pk differential input full scale), or
programmed with an external resistor divider to provide any
voltage level between 1 V and 2.5 V.
However, optimum noise and
distortion performance for the AD9260 can only be achieved with a
2.5 V reference as shown in Figure 46
.
For users wishing to operate the part at reduced clock frequen-
cies, the bias current of the AD9260 is designed to be scalable.
This scaling is accomplished through use of the proper external
resistor tied to the BIAS pin: the power can be reduced roughly
proportionately to clock frequency by as much as 75% (for clock
rates of 5 MHz). Refer to Figures 41
–
43 and 47
–
51 for charac-
terization curves showing performance tradeoffs.
ANALOG INPUT AND REFERENCE OVERVIEW
Figure 54, a simplified model of the AD9260, highlights the
relationship between the analog inputs, VINA, VINB and the
reference voltage VREF. Like the voltage applied to the top of
the resistor ladder in a flash A/D converter, the value VREF
defines the maximum input voltage to the A/D converter. An
internal reference buffer in the AD9260 scales the reference
voltage VREF before it is applied internally to the AD9260
LSB
DIFFERENTIATOR
V
IN
INT1
+
–
5B
DAC1
+
–
5B
DAC2
5B
ADC
INT2
5B
DAC
+
–
16
3B
ADC
3B
DAC
+
–
4
3B
ADC
3B
DAC
+
–
4
4B
ADC
PIPELINE CORRECTION LOGIC
8 LSBs
+ +
C
OUT
HALF-BAND
DECIMATION FILTER STAGE 1
HALF-BAND
DECIMATION FILTER STAGE 2
HALF-BAND
DECIMATION FILTER STAGE 3
Z
–
D
SHUFFLE
M
OUT
CONTROL/TEST
LOGIC
BANDGAP
REFERENCE
REFERENCE
BUFFER
OUTPUT BITS
Figure 53. Simplified Block Diagram
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD9260-EB | 制造商:Analog Devices 功能描述:Evaluation Board For AD9260 制造商:Analog Devices 功能描述:DEV TOOLS, EVAL BD FOR AD9260 - Bulk |
| AD9261-10EBZ | 功能描述:數(shù)據(jù)轉(zhuǎn)換 IC 開(kāi)發(fā)工具 16Bit 10 MHz Sigma Delta ADC EB RoHS:否 制造商:Texas Instruments 產(chǎn)品:Demonstration Kits 類型:ADC 工具用于評(píng)估:ADS130E08 接口類型:SPI 工作電源電壓:- 6 V to + 6 V |
| AD9261BCPZ-10 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16Bit 10 MHz Sigma Delta ADC RoHS:否 制造商:Analog Devices 通道數(shù)量: 結(jié)構(gòu): 轉(zhuǎn)換速率: 分辨率: 輸入類型: 信噪比: 接口類型: 工作電源電壓: 最大工作溫度: 安裝風(fēng)格: 封裝 / 箱體: |
| AD9261BCPZRL7-10 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16Bit 10 MHz Sigma Delta ADC RoHS:否 制造商:Analog Devices 通道數(shù)量: 結(jié)構(gòu): 轉(zhuǎn)換速率: 分辨率: 輸入類型: 信噪比: 接口類型: 工作電源電壓: 最大工作溫度: 安裝風(fēng)格: 封裝 / 箱體: |
| AD9262-10EBZ | 制造商:Analog Devices 功能描述:Evaluation Board For AD9262BCPZ10 制造商:Analog Devices 功能描述:EVALUATION BOARD FOR AD9262BCPZ-10 - Boxed Product (Development Kits) 制造商:Analog Devices 功能描述:BOARD EVALUATION 10MHZ AD9262 制造商:Analog Devices 功能描述:A/D Converter Eval. Board 制造商:Analog Devices 功能描述:AD9262, ADC, SPI, EVALUATION BOARD; Silicon Manufacturer:Analog Devices; Silicon Core Number:AD9262; Kit Application Type:Data Converter; Application Sub Type:ADC; Kit Contents:Software, Evaluation Board; MSL:MSL 3 - 168 hours 制造商:Analog Devices 功能描述:AD9262, ADC, SPI, EVALUATION BOARD; Silicon Manufacturer:Analog Devices; Silicon Core Number:AD9262; Kit Application Type:Data Converter; Application Sub Type:ADC; Kit Contents:Software, Evaluation Board; MSL:MSL 3 - 168 hours ;RoHS Compliant: Yes |
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