- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄383693 > OPA685N Ultra-Wideband, Current-Feedback OPERATIONAL AMPLIFIER With Disable TM PDF資料下載
參數(shù)資料
| 型號(hào)： | OPA685N |
| 英文描述： | Ultra-Wideband, Current-Feedback OPERATIONAL AMPLIFIER With Disable TM |
| 中文描述： | 超寬帶，電流反饋運(yùn)算放大器商標(biāo)使用禁用 |
| 文件頁數(shù)： | 21/28頁 |
| 文件大?。?/td> | 283K |
| 代理商： | OPA685N |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁當(dāng)前第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁
21
OPA685
For a 20mA peak output current DAC, the mid-scale current
of 10mA will give a 2V DC output common-mode operating
voltage due to the 200
resistor to ground at their outputs. The
total AC impedance at each output is 50
, giving a
±
0.5V
swing around this 2V common-mode voltage for the DAC.
These resistors also act as a current divider sending 75% of the
DAC output current through the feedback resistor (464
). The
blocking capacitor references the OPA685 output voltage to
ground, and turns the unipolar DAC output current into a
bipolar swing of 0.75 20mA 464
= 7Vp-p at each
amplifier output. Each output is exactly 180
°
out-of-phase
from the other, producing double 7Vp-p into the matching
resistors. To limit the peak output current and improve distor-
tion, the circuit of Figure 10 is set up with a 1.4:1 step-down
transformer. This reflects the 50
load to be 100
at the
primary side of the transformer. For the maximum 14Vp-p
swing across the outputs of the two amplifiers, the matching
resistors will drop this to 7Vp-p at the input of the transformer,
then down to 5Vp-p maximum at the 50
load at the output
of the transformer.
HIGH-SPEED ADC INPUT DRIVERS
The OPA685 is ideally suited to the demanding input drive
requirements of emerging ultra high-speed and high perfor-
mance ADCs. As a single amplifier stage, 10-bit converters
through 100MSPS may be driven, while 8-bit converters
may be driven with input frequencies in excess of 100MHz.
Emerging differential input ADCs can also benefit from a
purely differential input interface using two OPA685s to get
a significant improvement in even-order harmonics along
with a somewhat improved 3rd-order harmonic suppression.
SINGLE-ENDED ADC INPUT INTERFACE
Figure 11 shows an example single +5V supply ADC driver
where the AC gain is set to –8V/V. The converter is shown
with both an inverting and non-inverting input. The inverting
input is used here to make the overall channel non-inverting.
The Typical Performance Curves for the non-inverting gain
of +8 show very flat frequency response for +5V only
operation when driving into the 20pF load capacitor shown in
Figure 11. The inverting configuration of Figure 11 was
selected for higher slew rate and lower distortion perfor-
mance. It will give > 300MHz bandwidth at this gain of –8.
Harmonic distortion for a 2Vp-p output signal will be < –
50dBc through 50MHz.
DIFFERENTIAL ADC DRIVER
For applications requiring the lowest harmonic distortion
through very high frequencies, a balanced differential cir-
cuit using the OPA685 offers the best performance. Figure
12 shows an example of this approach where an input step-
up transformer is used to convert to a differential signal and
improve the Noise Figure.
FIGURE 11. Single Supply, Wideband ADC Driver.
FIGURE 12. Very Wideband Differential ADC Driver.
OPA685
42.2
V
O
= 2.5V
DC
– 8V
I
400
50
+5V
Power supply decoupling
not shown.
+5V
ADC
2k
2k
IN
20
0.1
μ
F
20pF
IN
CM
V
I
DIS
+5V
–5V
OPA685
22pF
22pF
+5V
–5V
600
OPA685
1:2
50
Source
V
I
Noise
Figure
11.8dB
V
CM
V
CM
600
100
100
43.2
Power supply decoupling
not shown.
43.2
V
O
ADC Input
V
O
V
I
= 12V/V (21.6dB)
DIS
DIS
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| OPA685U | Ultra-Wideband, Current-Feedback OPERATIONAL AMPLIFIER With Disable TM |
| OPA699ID | Wideband, High Gain VOLTAGE LIMITING AMPLIFIER |
| OPA699 | Wideband, High Gain VOLTAGE LIMITING AMPLIFIER |
| OPA699IDR | Wideband, High Gain VOLTAGE LIMITING AMPLIFIER |
| OPA708 | REFLECTIVE OBJECT SENSORS |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA685N/250 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Current-Feedback Operational Amplifier |
| OPA685N/3K | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Current-Feedback Operational Amplifier |
| OPA685U | 功能描述:高速運(yùn)算放大器 Ultra-Wideband RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| OPA685U/2K5 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Current-Feedback Operational Amplifier |
| OPA686 | 制造商:BB 制造商全稱:BB 功能描述:Wideband, Low Noise, Voltage Feedback OPERATIONAL AMPLIFIER |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。