参数资料
| 型号： | AD9042ASTZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 13/24页 |
| 文件大小： | 0K |
| 描述： | IC ADC 12BIT 41MSPS 44-TQFP |
| 标准包装： | 1 |
| 位数： | 12 |
| 采样率（每秒）： | 41M |
| 数据接口： | 并联 |
| 转换器数目： | 3 |
| 功率耗散（最大）： | 735mW |
| 电压电源： | 模拟和数字，双 ± |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 44-LQFP |
| 供应商设备封装： | 44-LQFP（10x10） |
| 包装： | 托盘 |
| 输入数目和类型： | 1 个单端，双极 |
| 产品目录页面： | 780 (CN2011-ZH PDF) |
AD9042
Rev. B | Page 20 of 24
Assuming that the C/N ratio must be 6 dB or better for accurate
demodulation, one of the eight signals can be reduced by 48.8 dB
before demodulation becomes unreliable. At this point, the
input signal power would be 40.6 μV rms on the ADC input or
74.8 dBm. Referenced to the antenna, this is 104.8 dBm.
IF SAMPLING, USING THE AD9042 AS A MIX-
DOWN STAGE
Because the performance of the AD9042 extends beyond the
baseband region into the second and third Nyquist zone, the
converter may find many uses as a mix-down converter in both
narrow-band and wideband applications. Many common IF
frequencies exist in this range of frequencies. If the ADC is used
to sample these signals, they are aliased down to baseband during
the sampling process in much the same manner that a mixer
downconverts a signal. For signals in various Nyquist zones, the
following equations may be used to determine the final
frequency after aliasing.
To improve sensitivity, several things can be done. First, the
noise figure of the receiver can be reduced. Because front-end
noise dominates the 0.529 mV rms, each dB reduction in noise
figure translates to an additional dBc of sensitivity. Second,
providing broadband AGC can improve sensitivity by the range
of the AGC. However, the AGC only provides useful
improvements if all in-band signals are kept to an absolute
minimal power level so that AGC can be kept near the
maximum gain.
f1NYQUISTS = fSAMPLE fSIGNAL
f2NYQUISTS = abs (fSAMPLE fSIGNAL)
f3NYQUISTS = 2 × (fSAMPLE fSIGNAL)
f4NYQUISTS = abs (2 × fSAMPLE fSIGNAL)
This noise-limited example does not adequately demonstrate
the true limitations in a wideband receiver. Other limitations
such as SFDR are more restrictive than SNR and noise. Assume
that the ADC has an SFDR specification of 80 dBFS or 76
dBm (full scale = 4 dBm). Also assume that a tolerable carrier-
to-interferer (C/I) (different from C/N) ratio is 18 dB (C/I is the
ratio of signal to in-band interfere). This means that the
minimum signal level is 62 dBFS (80 plus 18) or 58 dBm.
At the antenna, this is 88 dBm. Therefore, as can be seen,
SFDR (single or multitone) would limit receiver performance in
this example. However, SFDR can be greatly improved through
the addition of the out-of-band dither can improve receiver
sensitivity nearly to that limited by thermal noise.
Using the converter to alias down these narrow-band or
wideband signals has many potential benefits. First and
foremost is the elimination of a complete mixer stage, along
with amplifiers, filters, and other devices, reducing cost and
power dissipation.
One common example is the digitization of a 21.4 MHz IF using a
10 MSPS sample clock. Using the equation for the fifth Nyquist
zone, the resultant frequency after sampling is 1.4 MHz. Figure 44
shows performance under these conditions. Even under these
conditions, the AD9042 typically maintains better than 80 dB
SFDR.
FREQUENCY (MHz)
0
–80
–120
–40
–100
–20
–60
P
O
WE
R
E
LA
TIV
E
TO
A
D
C
F
U
LL
S
C
A
LE
(dB
)
dc
123
45
8
7
8
6
2
5
3
4
ENCODE = 10.0MSPS
AIN = 21.4MHz
00
55
4-
0
62
Multitone Performance
Figure 43 shows the AD9042 in a worst-case scenario of four
strong tones spaced fairly close together. In this plot, no dither
was used, and the converter still maintains 85 dBFS of spurious-
free range. As noted in the Overcoming Static Nonlinearities
with Dither section, a modest amount of dither introduced out-
of-band can be used to lower the nonlinear components.
FREQUENCY (MHz)
0
–80
–120
–40
–100
–20
–60
P
O
W
E
R
RE
L
AT
IV
E
T
O
ADC
F
U
L
S
CAL
E
(
d
B)
3
6
9
7
4
2
5
8
dc
20.5
16.4
12.3
8.2
4.1
ENCODE = 41MSPS
00
55
4-
06
1
Figure 44. IF Sampling at 21.4 MHz Input
Figure 43. Multitone Performance
相关PDF资料 |
PDF描述 |
|---|---|
| AD9051BRSRL-2V | IC ADC 10BIT 60MSPS 28-SSOP |
| AD9054ABSTZ-200 | IC ADC 8BIT 200MSPS 44-LQFP |
| AD9057BRS-RL40 | IC ADC 8BIT 40MSPS 20-SSOP T/R |
| AD9058AKD | IC ADC 8BIT DUAL 50MSPS 48-CDIP |
| AD9059BRS | IC ADC 8BIT DUAL 60MSPS 28-SSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD9042BD | 制造商:Analog Devices 功能描述:- Bulk |
| AD9042CHIPS | 制造商:AD 制造商全称:Analog Devices 功能描述:12-Bit, 41 MSPS Monolithic A/D Converter |
| AD9042D | 制造商:AD 制造商全称:Analog Devices 功能描述:12-Bit, 41 MSPS Monolithic A/D Converter |
| AD9042D/PCB | 制造商:AD 制造商全称:Analog Devices 功能描述:12-Bit, 41 MSPS Monolithic A/D Converter |
| AD9042DPCB | 制造商:AD 制造商全称:Analog Devices 功能描述:12-Bit, 41 MSPS Monolithic A/D Converter |
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