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參數(shù)資料
| 型號： | LTC2231IUP |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | ADC |
| 英文描述： | Electrical Specifications Subject to Change |
| 中文描述： | 1-CH 10-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64 |
| 封裝： | 9 X 9 MM, PLASTIC, MO-220-WNJR, QFN-64 |
| 文件頁數(shù)： | 18/28頁 |
| 文件大?。?/td> | 695K |
| 代理商： | LTC2231IUP |
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LTC2230/LTC2231
18
22301p
60) may be used to provide the common mode bias level.
V
CM
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 V
CM
pin must be bypassed to
ground close to the ADC with a 2.2
μ
F or greater capacitor.
Input Drive Impedance
As with all high performance, high speed ADCs, the
dynamic performance of the LTC2230/LTC2231 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,
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/(2F
ENCODE
); 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 LTC2230/LTC2231 being driven by an
RF transformer with a center tapped secondary. The
secondary center tap is DC biased with V
CM
, setting the
ADC input signal at its optimum DC level. Figure 3 shows
a 1:1 turns ratio transformer. 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 transformers have poor performance at frequen-
cies below 1MHz.
Figure 4 demonstrates the use of a differential amplifier to
convert a single ended input signal into a differential input
signal. The advantage of this method is that it provides low
frequency input response; however, the limited gain band-
width of most op amps will limit the SFDR at high input
frequencies.
Figure 5 shows a single-ended input circuit. The imped-
ance seen by the analog inputs should be matched. This
circuit is not recommended if low distortion is required.
The 25
resistors and 12pF capacitor on the analog inputs
serve two purposes: isolating the drive circuitry from the
sample-and-hold charging glitches and limiting the
wideband noise at the converter input. For input frequen-
cies higher than 100MHz, the capacitor may need to be
decreased to prevent excessive signal loss.
Figure 3. Single-Ended to Differential Conversion
Using a Transformer
Figure 4. Differential Drive with an Amplifier
APPLICATIU
W
U
U
Figure 5. Single-Ended Drive
25
25
25
25
0.1
μ
F
A
IN+
A
IN+
A
IN–
A
IN–
12pF
2.2
μ
F
V
CM
LTC2230/
LTC2231
ANALOG
INPUT
0.1
μ
F
T1
1:1
T1 = MA/COM ETC1-1T
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
22301 F03
25
25
A
IN+
A
IN+
A
IN–
A
IN–
12pF
2.2
μ
F
V
CM
LTC2230/
LTC2231
22301 F04
–
–
+
+
CM
ANALOG
INPUT
HIGH SPEED
DIFFERENTIAL
AMPLIFIER
AMPLIFIER = LTC6600-20, AD8138, ETC.
25
0.1
μ
F
ANALOG
INPUT
V
CM
A
IN
+
A
IN
+
A
IN
–
A
IN
–
10k
12pF
22301 F05
2.2
μ
F
10k
25
0.1
μ
F
LTC2230/
LTC2231
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相關代理商/技術參數(shù) |
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| LTC2231IUP#PBF | 功能描述:IC ADC 10BIT 135MSPS 64-QFN RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 標準包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應商設備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個單端，雙極 |
| LTC2231IUP#TRPBF | 功能描述:IC ADC 10BIT 135MSPS 64-QFN RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 位數(shù):12 采樣率（每秒）:3M 數(shù)據(jù)接口:- 轉換器數(shù)目:- 功率耗散（最大）:- 電壓電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-23-6 包裝:帶卷 (TR) 輸入數(shù)目和類型:- |
| LTC2231UP | 制造商:LINER 制造商全稱:Linear Technology 功能描述:10-Bit,170Msps/135Msps ADCs |
| LTC2232 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:14-Bit, 80Msps Low Power 3V ADC |
| LTC2232CUK | 功能描述:IC ADC 10BIT 105MSPS SAMPL 48QFN RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 標準包裝:1,000 系列:- 位數(shù):12 采樣率（每秒）:300k 數(shù)據(jù)接口:并聯(lián) 轉換器數(shù)目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數(shù)目和類型:1 個單端，單極；1 個單端，雙極 |
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