VREF V" />
參數(shù)資料
型號: AD8137YRZ-REEL
廠商: Analog Devices Inc
文件頁數(shù): 19/33頁
文件大小: 0K
描述: IC AMP DIFF R-R LP 20MA 8SOIC
標(biāo)準(zhǔn)包裝: 2,500
放大器類型: 差分
電路數(shù): 1
輸出類型: 差分,滿擺幅
轉(zhuǎn)換速率: 450 V/µs
-3db帶寬: 110MHz
電流 - 輸入偏壓: 500nA
電壓 - 輸入偏移: 700µV
電流 - 電源: 3.2mA
電流 - 輸出 / 通道: 20mA
電壓 - 電源,單路/雙路(±): 2.7 V ~ 12 V,± 2.7 V ~ 6 V
工作溫度: -40°C ~ 125°C
安裝類型: 表面貼裝
封裝/外殼: 8-SOIC(0.154",3.90mm 寬)
供應(yīng)商設(shè)備封裝: 8-SO
包裝: 帶卷 (TR)
Data Sheet
AD8137
Rev. E | Page 25 of 32
04771-0-018
GND
VREF
VREFA
ADR525A
2.5V SHUNT
REFERENCE
AD7450A
VIN+
VIN
VDD
AD8137
+
8
VREFB
2.5V
2
1
6
3
4
5
VOCM
1k
1k
1k
2.5k
1k
5V
50
50
VIN
1.0nF
0.1
F
0.1
F
+1.88V
+1.25V
VACM WITH
VREFB = 0
+0.63V
+2.5V
GND
–2.5V
Figure 65. AD8137 Driving AD7450A, 12-Bit ADC
The input impedance of a conventional inverting op amp
configuration is simply RG; however, it is higher in Equation 19
because a fraction of the differential output voltage appears at
the summing junctions, VAN and VAP. This voltage partially
bootstraps the voltage across the input resistor RG, leading to
the increased input resistance.
Input Common-Mode Swing Considerations
In some single-ended-to-differential applications, when using a
single-supply voltage, attention must be paid to the swing of the
input common-mode voltage, VACM.
Consider the case in Figure 65, where VIN is 5 V p-p swinging
about a baseline at ground and VREFB is connected to ground.
The input signal to the AD8137 is originating from a source
with a very low output resistance.
The circuit has a differential gain of 1.0 and β = 0.5. VICM has an
amplitude of 2.5 V p-p and is swinging about ground. Using the
results in Equation 16, the common-mode voltage at the inputs of
the AD8137, VACM, is a 1.25 V p-p signal swinging about a baseline
of 1.25 V. The maximum negative excursion of VACM in this case is
0.63 V, which exceeds the lower input common-mode voltage limit.
One way to avoid the input common-mode swing limitation is
to bias VIN and VREF at midsupply. In this case, VIN is 5 V p-p
swinging about a baseline at 2.5 V, and VREF is connected to a
low-Z 2.5 V source. VICM now has an amplitude of 2.5 V p-p and
is swinging about 2.5 V. Using the results in Equation 17, VACM
is calculated to be equal to VICM because VOCM = VICM. Therefore,
VICM swings from 1.25 V to 3.75 V, which is well within the input
common-mode voltage limits of the AD8137. Another benefit
seen by this example is that because VOCM = VACM = VICM, no
wasted common-mode current flows. Figure 66 illustrates a way
to provide the low-Z bias voltage. For situations that do not
require a precise reference, a simple voltage divider suffices to
develop the input voltage to the buffer.
04771-0-019
VIN
0V TO 5V
AD8137
+
8
2
1
6
3
4
5
VOCM
1k
1k
5V
1k
1k
10k
0.1
F
0.1
F
0.1
F
10
F
+
AD8031
+
0.1
F
5V
ADR525A
2.5V SHUNT
REFERENCE
TO
AD7450A
VREF
Figure 66. Low-Z Bias Source
Another way to avoid the input common-mode swing limitation
is to use dual power supplies on the AD8137. In this case, the
biasing circuitry is not required.
Bandwidth vs. Closed-Loop Gain
The 3 dB bandwidth of the AD8137 decreases proportionally
to increasing closed-loop gain in the same way as a traditional
voltage feedback operational amplifier. For closed-loop gains
greater than 4, the bandwidth obtained for a specific gain can
be estimated as
)
MHz
72
(
,
3
×
+
=
F
G
dm
O,
dB
R
V
f
(20)
or equivalently, β(72 MHz).
This estimate assumes a minimum 90° phase margin for the
amplifier loop, a condition approached for gains greater than 4.
Lower gains show more bandwidth than predicted by the equation
due to the peaking produced by the lower phase margin.
相關(guān)PDF資料
PDF描述
TSW-113-17-S-S CONN HEADER 13POS .100" SGL GOLD
AD8617ARMZ IC OPAMP GP R-R CMOS DUAL 8MSOP
TSW-117-17-S-S CONN HEADER 17POS .100" SGL GOLD
TSW-118-17-S-S CONN HEADER 18POS .100" SGL GOLD
TSW-119-17-S-S CONN HEADER 19POS .100" SGL GOLD
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD8137YRZ-REEL7 功能描述:IC AMP DIFF R-R LP 20MA 8SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 放大器類型:通用 電路數(shù):1 輸出類型:滿擺幅 轉(zhuǎn)換速率:0.11 V/µs 增益帶寬積:350kHz -3db帶寬:- 電流 - 輸入偏壓:4nA 電壓 - 輸入偏移:20µV 電流 - 電源:260µA 電流 - 輸出 / 通道:20mA 電壓 - 電源,單路/雙路(±):2.7 V ~ 36 V,±1.35 V ~ 18 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC(0.154",3.90mm 寬) 供應(yīng)商設(shè)備封裝:8-SO 包裝:帶卷 (TR)
AD8138 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Distortion Differential ADC Driver
AD8138_06 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Distortion Differential ADC Driver
AD81380703L 制造商:Analog Devices 功能描述:
AD8138AAR-EBZ 功能描述:BOARD EVAL FOR AD8138AAR RoHS:是 類別:編程器,開發(fā)系統(tǒng) >> 評估板 - 運(yùn)算放大器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:-