- 您现在的位置：买卖IC网 > PDF目录17063 > AD9764-EBZ (Analog Devices Inc)BOARD EVAL FOR AD9764 PDF资料下载
参数资料
| 型号： | AD9764-EBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 8/22页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR AD9764 |
| 产品培训模块： | DAC Architectures |
| 标准包装： | 1 |
| 系列： | TxDAC® |
| DAC 的数量： | 1 |
| 位数： | 14 |
| 采样率（每秒）： | 125M |
| 数据接口： | 并联 |
| 设置时间： | 35ns |
| DAC 型： | 电流 |
| 工作温度： | -40°C ~ 85°C |
| 已供物品： | 板 |
| 已用 IC / 零件： | AD9764 |
REV. B
AD9764
–16–
MULTITONE PERFORMANCE CONSIDERATIONS AND
CHARACTERIZATION
The frequency domain performance of high speed DACs has
traditionally been characterized by analyzing the spectral output
of a reconstructed full-scale (i.e., 0 dBFS), single-tone sine wave
at a particular output frequency and update rate. Although this
characterization data is useful, it is often insufficient to reflect a
DAC’s performance for a reconstructed multitone or spread-
spectrum waveform. In fact, evaluating a DAC’s spectral
performance using a full-scale, single tone at the highest specified
frequency (i.e., fH) of a bandlimited waveform is typically
indicative of a DAC’s “worst-case” performance for that given
waveform. In the time domain, this full-scale sine wave repre-
sents the lowest peak-to-rms ratio or crest factor (i.e., VPEAK/V
rms) that this bandlimited signal will encounter.
MAGNITUDE
–
dBm
FREQUENCY – MHz
–10
–70
–110
2.19
2.81
2.25
2.31
2.38
2.44
2.50
2.56
2.63
2.69
2.75
–20
–60
–80
–100
–40
–50
–90
–30
Figure 39a. Multitone Spectral Plot
TIME
1.0000
0.8000
–1.0000
VOLTS
–0.2000
–0.4000
–0.6000
–0.8000
0.2000
0.0000
0.4000
0.6000
Figure 39b. Time Domain “Snapshot” of the Multitone
Waveform
However, the inherent nature of a multitone, spread spectrum,
or QAM waveform, in which the spectral energy of the wave-
form is spread over a designated bandwidth, will result in a
higher peak-to-rms ratio when compared to the case of a simple
sine wave. As the reconstructed waveform’s peak-to-average
ratio increases, an increasing amount of the signal energy is
concentrated around the DAC’s midscale value. Figure 39a is
just one example of a bandlimited multitone vector (i.e., eight
tones) centered around one-half the Nyquist bandwidth (i.e.,
fCLOCK/4). This particular multitone vector, has a peak-to-rms
ratio of 13.5 dB compared to a sine waves peak-to-rms ratio of
3 dB. A “snapshot” of this reconstructed multitone vector in the
time domain as shown in Figure 39b reveals the higher signal
content around the midscale value. As a result, a DAC’s
“small-scale” dynamic and static linearity becomes increas-
ingly critical in obtaining low intermodulation distortion and
maintaining sufficient carrier-to-noise ratios for a given modula-
tion scheme.
A DAC’s small-scale linearity performance is also an important
consideration in applications where additive dynamic range is
required for gain control purposes or “predistortion” signal
conditioning. For instance, a DAC with sufficient dynamic
range can be used to provide additional gain control of its
reconstructed signal. In fact, the gain can be controlled in
6 dB increments by simply performing a shift left or right on the
DAC’s digital input word. Other applications may intentionally
predistort a DAC’s digital input signal to compensate for
nonlinearities associated with the subsequent analog compo-
nents in the signal chain. For example, the signal compression
associated with a power amplifier can be compensated for by
predistorting the DAC’s digital input with the inverse nonlinear
transfer function of the power amplifier. In either case, the
DAC’s performance at reduced signal levels should be carefully
evaluated.
A full-scale single tone will induce all of the dynamic and static
nonlinearities present in a DAC that contribute to its distortion
and hence SFDR performance. Referring to Figure 3, as the
frequency of this reconstructed full-scale, single-tone waveform
increases, the dynamic nonlinearities of any DAC (i.e., AD9764)
tend to dominate thus contributing to the rolloff in its SFDR
performance. However, unlike most DACs, which employ an R-2R
ladder for the lower bit current segmentation, the AD9764 (as
well as other TxDAC members) exhibits an improvement in
distortion performance as the amplitude of a single tone is re-
duced from its full-scale level. This improvement in distortion
performance at reduced signal levels is evident if one compares
the SFDR performance vs. frequency at different amplitudes
(i.e., 0 dBFS, –6 dBFS and –12 dBFS) and sample rates as
shown in Figures 4 through 7. Maintaining decent “small-scale”
linearity across the full span of a DAC transfer function is also
critical in maintaining excellent multitone performance.
Although characterizing a DAC’s multitone performance tends
to be application-specific, much insight into the potential per-
formance of a DAC can also be gained by evaluating the DAC’s
swept power (i.e., amplitude) performance for single, dual and
multitone test vectors at different clock rates and carrier frequen-
cies. The DAC is evaluated at different clock rates when recon-
structing a specific waveform whose amplitude is decreased in
3 dB increments from full-scale (i.e., 0 dBFS). For each specific
waveform, a graph showing the SFDR (over Nyquist) perfor-
mance vs. amplitude can be generated at the different tested
clock rates as shown in Figures 9–11. Note that the carrier(s)-
to-clock ratio remains constant in each figure. In each case, an
improvement in SFDR performance is seen as the amplitude is
reduced from 0 dBFS to approximately –9.0 dBFS.
A multitone test vector may consist of several equal amplitude,
spaced carriers each representative of a channel within a defined
bandwidth as shown in Figure 39a. In many cases, one or more
tones are removed so the intermodulation distortion performance
相关PDF资料 |
PDF描述 |
|---|---|
| HCM11DSEH-S243 | CONN EDGECARD 22POS .156 EYELET |
| GCM18DCTN-S288 | CONN EDGECARD 36POS .156 EXTEND |
| GCM18DCTH-S288 | CONN EDGECARD 36POS .156 EXTEND |
| HBM11DSEH-S243 | CONN EDGECARD 22POS .156 EYELET |
| AD9762-EBZ | BOARD EVAL FOR AD9762 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD9765 | 制造商:AD 制造商全称:Analog Devices 功能描述:Analog Devices: Data Converters: DAC 12-Bit, 10 ns to 100 ns Converters Selection Table |
| AD97651 | 制造商:AD 制造商全称:Analog Devices 功能描述:12-Bit, 125 MSPS Dual TxDAC+ D/A Converter |
| AD9765AST | 功能描述:数模转换器- DAC 12-Bit 125 MSPS Dual TxDAC+ RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube |
| AD9765ASTRL | 制造商:Analog Devices 功能描述:DAC 2-CH Segment 12-bit 48-Pin LQFP T/R 制造商:Analog Devices 功能描述:DAC DUAL CURRENT STEERING 12-BIT 48LQFP - Tape and Reel 制造商:Rochester Electronics LLC 功能描述:12-BIT, 125 MSPS DUAL TXDAC+ - Tape and Reel 制造商:Analog Devices Inc. 功能描述:Digital to Analog Converters - DAC 12-Bit 125 MSPS Dual TxDAC+ 制造商:Analog Devices Inc. 功能描述:Digital to Analog Converters - DAC 12-Bit 125 MSPS Dual 制造商:Analog Devices 功能描述:CONVERTER - DAC |
| AD9765ASTZ | 功能描述:IC DAC 12BIT DUAL 125MSPS 48LQFP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TxDAC+® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:50 系列:- 设置时间:4µs 位数:12 数据接口:串行 转换器数目:2 电压电源:单电源 功率耗散（最大）:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-uMAX 包装:管件 输出数目和类型:2 电压，单极 采样率（每秒）:* 产品目录页面:1398 (CN2011-ZH PDF) |
发布紧急采购，3分钟左右您将得到回复。