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參數(shù)資料
| 型號： | OPA3684IDR |
| 英文描述： | Operational Amplifier |
| 中文描述： | 運(yùn)算放大器 |
| 文件頁數(shù)： | 16/25頁 |
| 文件大?。?/td> | 448K |
| 代理商： | OPA3684IDR |
OPA3684
SBOS241A
16
www.ti.com
The first stage buffers the video DAC output to the first
3rd-order filter section. This stage also provides group delay
equalization while the 2nd and 3rd stages each give a 3rd-
order low-pass response with sin(x)/x equalization. Figure 10
shows the frequency response for the filter of Figure 9.
OPERATING SUGGESTIONS
SETTING RESISTOR VALUES TO OPTIMIZE BANDWIDTH
Any current-feedback op amp like the OPA3684 can hold
high bandwidth over signal-gain settings with the proper
adjustment of the external resistor values. A low-power part
like the OPA3684 typically shows a larger change in band-
width due to the significant contribution of the inverting input
impedance to loop-gain changes as the signal gain is changed.
Figure 11 shows a simplified analysis circuit for any current-
feedback amplifier.
BOARD
PART
NUMBER
LITERATURE
REQUEST
NUMBER
PRODUCT
PACKAGE
OPA3684ID
OPA3684IDBQ
SO-14
SSOP-16
DEM-OPA368xD
DEM-OPA368xDBQ
SBOU018
SBOU019
DESIGN-IN TOOLS
DEMONSTRATION BOARDS
Two PC boards are available to assist in the initial evaluation
of circuit performance using the OPA3684 in its two package
styles. Both of these are available, free, as an unpopulated
PC board delivered with descriptive documentation. The
summary information for these boards is shown in Table I.
20
10
0
–
10
–
20
–
30
–
40
–
50
0
1
10
100
Frequency (MHz)
(
f
–
3dB
FIGURE 10. Video Filter Frequency Response.
MACROMODELS
Computer simulation of circuit performance using SPICE is
often useful in predicting the performance of analog circuits
and systems. This is particularly true for Video and RF
amplifier circuits where parasitic capacitance and inductance
can have a major effect on circuit performance. Check the TI
web site (www.ti.com) for SPICE macromodels within the
OPA3684 product folder. These models do a good job of
predicting small-signal AC and transient performance under
a wide variety of operating conditions. They do not do as well
in predicting distortion or dG/dP characteristics. Most of
these models do not attempt to distinguish between the
package types in their small-signal AC performance.
R
F
V
O
R
G
R
I
Z
(S)
i
ERR
i
ERR
α
V
I
FIGURE 11. Current-Feedback Transfer Function Analysis
Circuit.
The key elements of this current-feedback op amp model
are:
α
Buffer gain from the noninverting input to the inverting input
R
I
Buffer output impedance
i
ERR
Feedback error current signal
Z
(S)
Frequency-dependent open-loop transimpedance gain
from i
ERR
to V
O
The buffer gain is typically very close to 1.00 and is normally
neglected from signal gain considerations. It will, however,
set the CMRR for a single op amp differential
amplifier configuration. For the buffer gain
α
< 1.0 and
CMRR =
–
20
log(1
–
α
). The closed-loop input stage buffer
used in the OPA3684 gives a buffer gain more closely
approaching 1.00 and this shows up in a slightly higher
CMRR than previous current-feedback op amps.
R
I
, the buffer output impedance, is a critical portion of the
bandwidth control equation. The OPA3684 reduces this
element to approximately 4.0
using the local loop gain of
the input buffer stage. This significant reduction in output
impedance, on very low power, contributes significantly to
extending the bandwidth at higher gains.
A current-feedback op amp senses an error current in the
inverting node (as opposed to a differential input error volt-
age for a voltage-feedback op amp) and passes this on to
the output through an internal frequency-dependent
TABLE I. Demo Board Ordering Information.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| OPA3690ID | OP-AMP|TRIPLE|BIPOLAR|SOP|16PIN|PLASTIC |
| OPA3690IDBQR | 1MHZ 128K I2C SERIAL EEPROM, -40C to +85C, 8-MSOP, T/R |
| OPA3690IDBQT | OP-AMP|TRIPLE|BIPOLAR|SSOP|16PIN|PLASTIC |
| OPA3690IDR | OP-AMP|TRIPLE|BIPOLAR|SOP|16PIN|PLASTIC |
| OPA3691ID | Current-Feedback Operational Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA3684IDRG4 | 功能描述:高速運(yùn)算放大器 Low-Power Triple Current Feedback 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 |
| OPA369 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:1.8V, 700nA, Zer?-Crossover RAIL-TO-RAIL I/O OPERATIONAL AMPLIFIER |
| OPA369_1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:1.8V, 700nA, Zer?-Crossover RAIL-TO-RAIL I/O OPERATIONAL AMPLIFIER |
| OPA3690 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Dual, Wideband, High Output Current, Operational Amplifier with Current Limit |
| OPA3690ID | 功能描述:高速運(yùn)算放大器 Triple Wideband Voltage-Feedback 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 |
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