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參數(shù)資料
| 型號： | OPA680N |
| 英文描述： | Wideband, Voltage Feedback OPERATIONAL AMPLIFIER With Disable TM |
| 中文描述： | 寬帶，電壓反饋運算放大器，禁用商標 |
| 文件頁數(shù)： | 13/21頁 |
| 文件大?。?/td> | 235K |
| 代理商： | OPA680N |
13
OPA680
OPA680
50
2k
82.5
75
Cable
75
Load
RG-59
82.5
75
402
340
Video 1
+5V
+5V
–5V
OPA680
50
2k
75
402
340
Video 2
–5V
+5V
V
DIS
DIS
DIS
DC gain for this circuit is equal to R
F
. At high frequencies,
the DAC output capacitance will produce a zero in the
noise gain for the OPA680 that may cause peaking in the
closed-loop frequency response. C
F
is added across R
F
to
compensate for this noise gain peaking. To achieve a flat
transimpedance frequency response, the pole in the feed-
back network should be set to:
1/2
π
R
F
C
F
=
√
GBP/4
π
R
F
C
D
which will give a closed-loop transimpedance bandwidth
f
–3dB
, of approximately:
f
–3dB
=
√
GBP/(2
π
R
F
C
D
)
FIGURE 6. Two-Channel Video Multiplexer.
WIDEBAND VIDEO MULTIPLEXING
One common application for video speed amplifiers which
include a disable pin is to wire multiple amplifier outputs
together, then select which one of several possible video
inputs to source onto a single line. This simple “Wired-OR
Video Multiplexer” can be easily implemented using the
OP680 as shown in Figure 6.
Typically, channel switching is performed either on sync or
retrace time in the video signal. The two inputs are approxi-
mately equal at this time. The “make-before-break” disable
characteristic of the OPA680 ensures that there is always
one amplifier controlling the line when using a wired-OR
circuit like that shown in Figure 6. Since both inputs may be
on for a short period during the transition between channels,
the outputs are combined through the output impedance
matching resistors (82.5
in this case). When one channel is
disabled, its feedback network forms part of the output
impedance and slightly attenuates the signal in getting out
onto the cable. The gain and output matching resistor have
been slightly increased to get a signal gain of +1 at the
matched load and provide a 75
output impedance to the
cable. The video multiplexer connection (Figure 6) also
insures that the maximum differential voltage across the
inputs of the unselected channel do not exceed the rated
±
1.2V maximum for standard video signal levels.
The section on Disable Operation shows the turn-on and
turn-off switching glitches using a grounded input for a
single channel is typically less than
±
50mV. Where two
outputs are switched (as shown in Figure 6), the output line
is always under the control of one amplifier or the other due
to the “make-before-break” disable timing. In this case, the
switching glitches for two 0V inputs drop to <20mV.
FIGURE 5. DAC Transimpedance Amplifier.
OPA680
High Speed
DAC
V
O
= I
O
R
F
R
F
C
F
GBP
→
Gain Bandwidth
Product (Hz) for the OPA680
C
D
I
O
I
O
50
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| OPA680P | Wideband, Voltage Feedback OPERATIONAL AMPLIFIER With Disable TM |
| OPA681U | Wideband, Current Feedback OPERATIONAL AMPLIFIER With Disable |
| OPA681 | Wideband, Current Feedback OPERATIONAL AMPLIFIER With Disable |
| OPA681N | Wideband, Current Feedback OPERATIONAL AMPLIFIER With Disable |
| OPA681P | Wideband, Current Feedback OPERATIONAL AMPLIFIER With Disable |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA680N/250 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
| OPA680N/3K | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
| OPA680P | 功能描述:高速運算放大器 Wideband V Feedb RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補償電壓: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 |
| OPA680U | 制造商:BB 制造商全稱:BB 功能描述:EVALUATION FIXTURE |
| OPA680U/2K5 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
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