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參數(shù)資料
| 型號(hào)： | EL4390C |
| 元件分類： | 視頻放大器 |
| 英文描述： | 80 MHz Video Amplifier with DC Restore(80 MHz，視頻放大器（帶直流恢復(fù)）) |
| 中文描述： | 80兆赫視頻放大器直流還原（80兆赫，視頻放大器（帶直流恢復(fù)）） |
| 文件頁(yè)數(shù)： | 16/16頁(yè) |
| 文件大?。?/td> | 309K |
| 代理商： | EL4390C |
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EL4390C
Triple 80 MHz Video Amplifier with DC Restore
Applications Information
Circuit Operation
Each channel of the EL4390 contains a current
feedback amplifier and a TTLCMOS compatible
clamp circuit The current that the clamp can
source or sink into the non-inverting input is ap-
proximately
I e (VCLAMP b VINa) 120
So when the non-inverting input is at the same
voltage as the clamp reference no current will
flow and hence no charge is added to the capaci-
tor When there is a difference in voltage current
will flow in an attempt to cancel the error AT
THE NON-INVERTING input The amplifier’s
offset voltage and (IBb c RF) DC errors are not
cancelled with this loop It is purely a method of
adding a controlled DC offset to the signal
As well as the offset voltage error which goes up
with gain and the IBb c RF error which drops
with gain there is also the IBa error term Since
the amplifier is capacitively coupled this small
current is slowly integrated and shows up as a
very slow ramp voltage Table below shows the
output voltage drift in 60
mS for various values of
coupling capacitor all assuming the very worst
IBa current
Table 1 Charge Storage Capacitor Value vs
Droop and Charging Rates
Cap Value
Droop in
Charge in
(nF)
60mS (mV)
2mS (mV)
4mS (mV)
10
30
400
800
22
136
182
364
47
64
85
170
100
30
40
80
220
136
18
36
In normal circuit operation the picture content
will also cause a slow change in voltage across the
capacitor so at every back porch time period
these error terms can be corrected
When a signal source is being switched eg from
two different surveillance cameras it is recom-
mended to synchronize the switching with the
vertical blanking period and to drive the HOLD
pin (pin 6) low during these lines This will en-
sure that the system has been completely re-
stored regardless of the average intensity of the
two pictures
Application Hints
Figures12 shows a three channel DC-restoring
system suitable for R-G-B or Y-U-V component
video or three synchronous composite signals
Figure 1 shows the amplifiers configured for non-
inverting gain and Figure 2 shows the amplifiers
configured for inverting gains Note that since
the DC-restoring function is accomplished by
clamping the amplifier’s non-inverting input
during the back porch period any signal on the
non-inverting input will be distorted For this
reason it is recommended to use the inverting
configuration for composite video
since this
avoids the color burst being altered during the
clamp time period
Since all three amplifiers are monolithic they
run at the same temperature and will have very
similar input bias currents This can be used to
advantage in situations where the droop voltage
needs to be compensated since a single trim cir-
cuit can be used for all three channels A 560K
X
or similar value resistor helps to isolate each sig-
nal See Figure 2 The advantage of compensat-
ing for the droop voltage is that a smaller capaci-
tor can be used which allows a larger level resto-
ration within one line See Table 1 for values of
capacitor and chargedroop rates
9
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| EL4390 | Triple 80 MHz Video Amplifier with DC Restore |
| EL4390CM | Triple 80 MHz Video Amplifier with DC Restore |
| EL4390CN | Triple 80 MHz Video Amplifier with DC Restore |
| EL4393C | Triple 80 MHz Video Amplifier(三路，80 MHz，視頻放大器) |
| EL4393 | Triple 80 MHz Video Amplifier w/Disable |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| EL4390CM | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Triple 80MHz Video Amplifier with DC Restore |
| EL4390CN | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Triple 80MHz Video Amplifier with DC Restore |
| EL4393 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Triple 80MHz Video Amplifier w/Disable |
| EL4393C | 制造商:ELANTEC 制造商全稱:ELANTEC 功能描述:Triple 80 MHz Video Amplifier w/Disable |
| EL4393CM | 制造商:Rochester Electronics LLC 功能描述:80 MHZ TRIPLE CMF OP AMP - Bulk |
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