參數(shù)資料
型號： AD9278BBCZ
廠商： Analog Devices Inc
文件頁數(shù)： 18/44頁
文件大?。?/td> 0K
描述： IC ADC 12BIT 50MSPS 144CSPBGA
標(biāo)準(zhǔn)包裝： 1
類型： AAF，ADC，解調(diào)器，LNA，VGA
分辨率（位）： 12 b
采樣率（每秒）： 50M
數(shù)據(jù)接口： 串行，SPI?
電壓電源： 模擬和數(shù)字
電源電壓： 1.7 V ~ 1.9 V，2.7 V ~ 3.6 V
工作溫度： -40°C ~ 85°C
安裝類型： 表面貼裝
封裝/外殼： 144-LFBGA，CSPBGA
供應(yīng)商設(shè)備封裝： 144-CSPBGA（10x10）
包裝： 托盤
Data Sheet
AD9278
Rev. A | Page 25 of 44
The main purpose of input impedance matching is to improve the
transient response of the system. With shunt termination, the input
noise increases due to the thermal noise of the matching resistor
and the increased contribution of the LNA input voltage noise
generator. With active termination, however, the contributions
of both are smaller (by a factor of 1/(1 + LNA Gain)) than they
would be for shunt termination.
Figure 45 shows the relative noise figure performance. With an
LNA gain of 21.3 dB, the input impedance was swept with RS to
preserve the match at each point. The noise figures for a source
impedance of 50 Ω are 7.3 dB, 4.2 dB, and 2.8 dB for the shunt
termination, active termination, and unterminated configurations,
respectively. The noise figures for 200 Ω are 4.5 dB, 1.7 dB, and
1.0 dB, respectively.
Figure 46 shows the noise figure as it relates to RS for various
values of RIN, which is helpful for design purposes.
10
100
1k
0
1.5
3.0
4.5
6.0
7.5
9.0
10.5
12.0
RS ()
NO
IS
E
F
IG
U
RE
(
d
B)
UNTERMINATED
SHUNT TERMINATION
ACTIVE TERMINATION
09
42
4-
0
42
Figure 45. Noise Figure vs. RS for Shunt Termination, Active
Termination Matched and Unterminated Inputs, VGAIN = 1.6 V
10
100
1k
0
1
2
3
4
5
6
7
8
RS ()
NO
IS
E
F
IG
U
RE
(
d
B)
09
42
4-
0
43
RIN = 50
RIN = 75
RIN = 100
RIN = 200
UNTERMINATED
Figure 46. Noise Figure vs. RS for Various Fixed Values of RIN,
Active Termination Matched Inputs, VGAIN = 1.6 V
Input Overdrive
Excellent overload behavior is of primary importance in
ultrasound. Both the LNA and VGA have built-in overdrive
protection and quickly recover after an overload event.
As with any amplifier, voltage clamping prior to the inputs
is highly recommended if the application is subject to high
Figure 47 shows a simplified ultrasound transducer interface.
A common transducer element serves the dual functions of
transmitting and receiving ultrasound energy. During the
transmitting phase, high voltage pulses are applied to the ceramic
elements. A typical transmit/receive (T/R) switch can consist of
four high voltage diodes in a bridge configuration. Although the
diodes ideally block transmit pulses from the sensitive receiver
input, diode characteristics are not ideal, and the resulting leakage
transients imposed on the LI-x inputs can be problematic.
The external input overload protection scheme also contains a
pair of back-to-back signal diodes that should be in place prior to
the ac coupling capacitors. Keep in mind that all diodes are prone
to exhibiting some amount of shot noise. Many types of diodes are
available for achieving the desired noise performance. The
configuration shown in Figure 47 tends to add 2 nV/√Hz of
input-referred noise. Decreasing the 5 kΩ resistor and increasing
the 2 kΩ resistor may improve noise contribution, depending on
the application. With the diodes shown in Figure 47, clamping
levels of ±0.5 V or less significantly enhance the overload
performance of the system.
Because ultrasound is a pulse system and time-of-flight is used
to determine depth, quick recovery from input overloads is
essential. Overload can occur in the preamplifier and in the
VGA. Immediately following a transmit pulse, the typical VGA
gains are low, and the LNA is subject to overload from T/R
switch leakage. With increasing gain, the VGA can become
overloaded due to strong echoes that occur near field echoes
and acoustically dense materials, such as bone.
TRANSDUCER
10nF
2k
5k
AD9278
Tx
DRIVER
HV
+5V
–5V
LNA
09
42
4-
04
4
Figure 47. Input Overload Protection
相關(guān)PDF資料
PDF描述
AD9279BBCZ IC ADC 12BIT 80MSPS 144CSPBGA
AD9393BBCZRL-80 IC INTERFACE 80MHZ HDMI 76CSPBGA
AD9398KSTZ-150 IC INTERFACE 150MHZ HDMI 100LQFP
AD9708ARU IC DAC 8BIT 100MSPS 28-TSSOP
AD974BN IC DAS 16BIT 4CH 200KSPS 28-DIP
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD9279 制造商:AD 制造商全稱:Analog Devices 功能描述:Octal LNA/VGA/AAF/ADC and CW I/Q Demodulator
AD9279-65EBZ 功能描述:BOARD EVALUATION FOR AD9279 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- ADC 的數(shù)量:1 位數(shù):12 采樣率（每秒）:94.4k 數(shù)據(jù)接口:USB 輸入范圍:±VREF/2 在以下條件下的電源（標(biāo)準(zhǔn)）:- 工作溫度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，軟件
AD9279-80KITZ 功能描述:KIT EVALUATION FOR AD9279 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- ADC 的數(shù)量:1 位數(shù):12 采樣率（每秒）:94.4k 數(shù)據(jù)接口:USB 輸入范圍:±VREF/2 在以下條件下的電源（標(biāo)準(zhǔn)）:- 工作溫度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，軟件
AD9279BBCZ 功能描述:IC ADC 12BIT 80MSPS 144CSPBGA RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - ADCs/DAC - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:50 系列:- 類型:數(shù)據(jù)采集系統(tǒng)（DAS） 分辨率（位）:16 b 采樣率（每秒）:21.94k 數(shù)據(jù)接口:MICROWIRE?，QSPI?，串行，SPI? 電壓電源:模擬和數(shù)字 電源電壓:1.8 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（6x6） 包裝:托盤
AD9279-BBCZ 制造商:AD 制造商全稱:Analog Devices 功能描述:Octal LNA/VGA/AAF/ADC and CW I/Q Demodulator
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*