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参数资料
| 型号： | LTC6420IUDC-20#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/14页 |
| 文件大小： | 0K |
| 描述： | IC DIFF AMP/ADC DRIVER DL 20QFN |
| 标准包装： | 91 |
| 类型： | ADC 驱动器 |
| 应用： | 数据采集 |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-WFQFN 裸露焊盘 |
| 供应商设备封装： | 20-QFN（3x4） |
| 包装： | 管件 |
LTC6420-20
9
642020fb
matching network while the other input is connected to the
same matching network and a source resistor. Because the
return ratios of the two feedback paths are equal, the two
outputs have the same gain and thus symmetrical swing. In
general, the single-ended input impedance and termination
resistor RT are determined by the combination of RS, RG
and RF. For example, when RS is 50Ω, it is found that the
single-ended input impedance is 202Ω and RT is 66.5Ω
in order to match to a 50Ω source impedance.
The LTC6420-20 is unconditionally stable. However,
the overall differential gain is affected by both source
impedance and load impedance as follows:
A
V =
V
OUT
V
IN
=
2000
R
S + 200
R
L
25 + RL
Output Impedance Match
The LTC6420-20 can drive an ADC directly without external
output impedance matching. Alternatively, the differential
output impedance of 25Ω can be matched to a higher
value impedance, e.g. 50Ω, by series resistors or an LC
network.
Output Common Mode Adjustment
The output common mode voltage is set by the VOCM pin,
which is a high impedance input. The output common
mode voltage is capable of tracking VOCM in a range from
1.1V to 1.6V. The bandwidth of VOCM control is typically
15MHz, which is dominated by a low pass lter connected
to the VOCM pin and is aimed to reduce common mode
noise generation at the outputs. The internal common
mode feedback loop has a –3dB bandwidth of 300MHz,
allowing fast rejection of any common mode output voltage
disturbance. The VOCM pin should be tied to a DC bias
voltage with a 0.1μF bypass capacitor. When interfacing
with A/D converters such as the LTC22xx families, the
VOCM pin can be connected to the VCM pin of the ADC.
Driving A/D Converters
The LTC6420-20 has been specically designed to interface
directly with high speed A/D converters. The back page of
this data sheet shows the LTC6420-20 driving an LTC2285,
which is a dual 14-bit, 125Msps ADC.
The VOCM pins of the LTC6420-20 are connected to the
VCM pins of the LTC2285, which provide a DC voltage
level of 1.5V. Both ICs are powered from the same 3V
supply voltage.
The inputs to the LTC6420-20 can be congured in various
ways, as described in the Input Impedance and Matching
section of this data sheet. The outputs of the LTC6420-20
may be connected directly to the analog inputs of an ADC,
or a simple lowpass or bandpass lter network may be
inserted to reduce out-of-band noise.
Test Circuits
Due to the fully-differential design of the LTC6420 and
its usefulness in applications with differing characteristic
specications, two test circuits are used to generate the
information in this data sheet. Test Circuit A is DC1299, a
two-port demonstration circuit for the LTC6420/LTC6421
family. The schematic and silkscreen are shown in Figure 4.
This circuit includes input and output transformers (baluns)
for single-ended-to-differential conversion and impedance
transformation, allowing direct hook-up to a 2-port network
analyzer. There are also series resistors at the output to
avoid loading the amplier directly with a 50Ω load. Due
to the input and output transformers, the –3dB bandwidth
is reduced from 1.8GHz to approximately 1.3GHz.
Test Circuit B uses a 4-port network analyzer to measure
S-parameters and gain/phase response. This removes the
effects of the wideband baluns and associated circuitry,
for a true picture of the >1GHz S-parameters and AC
characteristics.
APPLICATIONS INFORMATION
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| LTC6421IUDC-20#TRPBF | IC ADC DRIVER DIFF 20-QFN |
| SY88993VKG | IC POST AMP CML LIMITING 10-MSOP |
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| VE-2T1-IV-F2 | CONVERTER MOD DC/DC 12V 150W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC6420IUDC-20-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Matched 1.8GHz Differential Amplifi ers/ADC Drivers |
| LTC6421-20 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Matched 1.3GHz Differential Amplifi ers/ADC Drivers |
| LTC6421CUDC-20#PBF | 功能描述:IC ADC DRIVER DIFF 20-QFN RoHS:是 类别:集成电路 (IC) >> 线性 - 放大器 - 专用 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:60 系列:- 类型:可变增益放大器 应用:CATV 安装类型:表面贴装 封装/外壳:20-WQFN 裸露焊盘 供应商设备封装:20-TQFN-EP（5x5） 包装:托盘 |
| LTC6421CUDC-20#TR | 制造商:Linear Technology 功能描述:DIFF-AMPLIFIER, 1.3GHZ, 4500V/US, QFN-20, No. of Amplifiers:2, Input Offset Voltage:400V, Bandwidth:1.3GHz, Amplifier Case Style:QFN, No. of Pins:20, Supply Voltage Range:2.85V to 3.5V, Slew Rate:4500V/s, Supply Current:40mA, MSL:-, RoHS Compliant: No |
| LTC6421CUDC-20#TRPBF | 功能描述:IC ADC DRIVER DIFF 20-QFN RoHS:是 类别:集成电路 (IC) >> 线性 - 放大器 - 专用 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:60 系列:- 类型:可变增益放大器 应用:CATV 安装类型:表面贴装 封装/外壳:20-WQFN 裸露焊盘 供应商设备封装:20-TQFN-EP（5x5） 包装:托盘 |
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