参数资料
型号: LTC2232IUK
厂商: Linear Technology
文件页数: 8/28页
文件大小: 0K
描述: IC ADC 10BIT 105MSPS SAMPL 48QFN
标准包装: 52
位数: 10
采样率(每秒): 105M
数据接口: 并联
转换器数目: 1
功率耗散(最大): 535mW
电压电源: 单电源
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 48-WFQFN 裸露焊盘
供应商设备封装: 48-QFN-EP(7x7)
包装: 管件
输入数目和类型: 1 个单端,双极; 1 个差分,双极
LTC2232/LTC2233
16
22323fa
During the sample phase when ENC is low, the transistors
connect the analog inputs to the sampling capacitors and
they charge to, and track the differential input voltage.
When ENC transitions from low to high, the sampled input
voltage is held on the sampling capacitors. During the hold
phase when ENC is high, the sampling capacitors are
disconnected from the input and the held voltage is passed
to the ADC core for processing. As ENC transitions from
high to low, the inputs are reconnected to the sampling
capacitors to acquire a new sample. Since the sampling
capacitors still hold the previous sample, a charging glitch
proportional to the change in voltage between samples will
be seen at this time. If the change between the last sample
and the new sample is small, the charging glitch seen at
the input will be small. If the input change is large, such as
the change seen with input frequencies near Nyquist, then
a larger charging glitch will be seen.
Single-Ended Input
For cost sensitive applications, the analog inputs can be
driven single-ended. With a single-ended input the har-
monic distortion and INL will degrade, but the SNR and
DNL will remain unchanged. For a single-ended input, AIN+
should be driven with the input signal and AIN– should be
connected to 1.6V or VCM.
Common Mode Bias
For optimal performance the analog inputs should be
driven differentially. Each input should swing
±0.5V for
the 2V range or
±0.25V for the 1V range, around a
common mode voltage of 1.6V. The VCM output pin (Pin
44) may be used to provide the common mode bias level.
VCM can be tied directly to the center tap of a transformer
to set the DC input level or as a reference level to an op amp
differential driver circuit. The VCM pin must be bypassed to
ground close to the ADC with a 2.2
F or greater capacitor.
Input Drive Impedance
As with all high performance, high speed ADCs, the
dynamic performance of the LTC2232/LTC2233 can be
influenced by the input drive circuitry, particularly the
second and third harmonics. Source impedance and input
reactance can influence SFDR. At the falling edge of ENC,
APPLICATIO S I FOR ATIO
WU
U
the sample-and-hold circuit will connect the 1.6pF sam-
pling capacitor to the input pin and start the sampling
period. The sampling period ends when ENC rises, holding
the sampled input on the sampling capacitor. Ideally the
input circuitry should be fast enough to fully charge
the sampling capacitor during the sampling period
1/(2FENCODE); however, this is not always possible and the
incomplete settling may degrade the SFDR. The sampling
glitch has been designed to be as linear as possible to
minimize the effects of incomplete settling.
For the best performance, it is recommended to have a
source impedance of 100
or less for each input. The
source impedance should be matched for the differential
inputs. Poor matching will result in higher even order
harmonics, especially the second.
Input Drive Circuits
Figure 3 shows the LTC2232/LTC2233 being driven by an
RF transformer with a center tapped secondary. The
secondary center tap is DC biased with VCM, setting the
ADC input signal at its optimum DC level. Terminating on
the transformer secondary is desirable, as this provides a
common mode path for charging glitches caused by the
sample and hold. Figure 3 shows a 1:1 turns ratio trans-
former. Other turns ratios can be used if the source
impedance seen by the ADC does not exceed 100
for
each ADC input. A disadvantage of using a transformer is
the loss of low frequency response. Most small RF trans-
formers have poor performance at frequencies below
1MHz.
Figure 3. Single-Ended to Differential Conversion
Using a Transformer
25
25
25
25
0.1
F
AIN
+
AIN
2.2
F
VCM
LTC2232/
LTC2233
ANALOG
INPUT
0.1
FT1
1:1
T1 = MA/COM ETC1-1T
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
22323 F03
12pF
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LTC2232IUK#TRPBF 功能描述:IC ADC 10BIT 105MSPS SAMPL 48QFN RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 位数:12 采样率(每秒):3M 数据接口:- 转换器数目:- 功率耗散(最大):- 电压电源:- 工作温度:- 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-23-6 包装:带卷 (TR) 输入数目和类型:-
LTC2232UK 制造商:LINER 制造商全称:Linear Technology 功能描述:10-Bit,105Msps/80Msps ADCs
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