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參數(shù)資料
| 型號(hào)： | OPA694IDR |
| 英文描述： | Wideband, Low-Power, Current Feedback Operational Amplifier |
| 中文描述： | 寬帶，低功耗，電流反饋運(yùn)算放大器 |
| 文件頁數(shù)： | 13/24頁 |
| 文件大?。?/td> | 382K |
| 代理商： | OPA694IDR |
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SBOS319C SEPTEMBER 2004 REVISED NOVEMBER 2004
www.ti.com
13
DESIGN-IN TOOLS
DEMONSTRATION BOARDS
Two PC boards are available to assist in the initial
evaluation of circuit performance using the OPA694 in its
two package styles. Both are available free, as
unpopulated PC boards delivered with descriptive
documentation. The summary information for these
boards is shown in Table 1.
Table 1. Demo Board Listing
PRODUCT
PACKAGE
BOARD
PART NUMBER
LITERATURE
REQUEST
NUMBER
OPA694ID
SO-8
DEM-OPA84xD
SBOU026
OPA694IDBV
SOT23-5
DEM-OPA84xDBV
SBOU027
To request either of these boards, use the Texas
Instruments web site (www.ti.com).
MACROMODELS AND APPLICATIONS SUPPORT
Computer simulation of circuit performance using SPICE
is often useful when analyzing 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.
A SPICE model for the OPA694 is available through the TI
web site (www.ti.com). 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 the harmonic distortion or dG/d
φ
characteristics. These models do not attempt to
distinguish between package types in their small-signal
AC performance.
OPERATING SUGGESTIONS
SETTING RESISTOR VALUES TO
OPTIMIZE BANDWIDTH
A current-feedback op amp like the OPA694 can hold an
almost constant bandwidth over signal gain settings with
the proper adjustment of the external resistor values. This
is shown in the Typical Characteristic curves; the
small-signal bandwidth decreases only slightly with
increasing gain. Those curves also show that the feedback
resistor has been changed for each gain setting. The
resistor
values
on the inverting side of the circuit for a
current-feedback op amp can be treated as frequency
response compensation elements while their
ratios
set
the signal gain. Figure 8 shows the small-signal frequency
response analysis circuit for the OPA694.
R
F
V
O
R
G
R
I
Z
(S)
i
ERR
i
ERR
α
V
I
Figure 8. Recommended Feedback Resistor
Versus Noise Gain
The key elements of this current-feedback op amp model
are:
α
→
Buffer gain from the noninverting input to the
inverting input
R
I
i
ERR
→
Feedback error current signal
→
Frequency dependent open-loop transimpe-
dance gain from i
ERR
to V
O
→
Buffer output impedance
Z
(s)
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 a buffer gain
α
< 1.0, the
CMRR = –20
×
log (1–
α
) dB.
R
I
, the buffer output impedance, is a critical portion of the
bandwidth control equation. R
I
for the OPA694 is typically
about 30
.
A current-feedback op amp senses an error current in the
inverting node (as opposed to a differential input error
voltage for a voltage-feedback op amp) and passes this on
to the output through an internal frequency dependent
transimpedance gain. The Typical Characteristics show
this open-loop transimpedance response. This is
analogous to the open-loop voltage gain curve for a
voltage-feedback op amp. Developing the transfer
function for the circuit of Figure 8 gives Equation (1):
V
O
V
I
1
R
F
R
G
1
R
F
R
I
1
R
F
R
G
Z
(S)
NG
R
F
1
R
I
NG
Z
(S)
where:
NG
1
R
F
R
G
(1)
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA694IDRG4 | 功能描述:高速運(yùn)算放大器 WideBand Low-Power Curr Feedback Amp 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 |
| OPA695 | 制造商:BB 制造商全稱:BB 功能描述:Wideband, Low-Power, Current Feedback Operational Amplifier |
| OPA695ID | 功能描述:高速運(yùn)算放大器 Ultra-Wideband 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 |
| OPA695ID | 制造商:Texas Instruments 功能描述:IC SM OP-AMP WIDEBAND CFB |
| OPA695IDBVR | 功能描述:高速運(yùn)算放大器 Ultra-Wideband 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 |
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