參數(shù)資料
型號(hào)： THS7364IPWR
廠商： TEXAS INSTRUMENTS INC
元件分類(lèi)： 音頻／視頻放大
英文描述： 6 CHANNEL, VIDEO AMPLIFIER, PDSO20
封裝： GREEN, PLASTIC, TSSOP-20
文件頁(yè)數(shù)： 30/47頁(yè)
文件大小： 1134K
代理商： THS7364IPWR
SBOS530 – AUGUST 2010
www.ti.com
achieve
BENEFITS OVER PASSIVE FILTERING
54 dB of attenuation at 27 MHz—a common sampling
Two key benefits of using an integrated filter system,
frequency between the DAC/ADC second and third
such as the THS7364, over a passive system are
Nyquist zones found in many video systems. This
PCB area and filter variations. The small TSSOP-20
consideration is important because any signal that
package for six video channels is much smaller over
appears around this frequency can also appear in the
a passive RLC network, especially a six-pole passive
baseband as a result of aliasing effects of an ADC
network. Additionally, consider that inductors have at
found in a receiver.
best ±10% tolerances (normally, ±15% to ±20% is
The THS7364 FHD filters have a nominal corner
common)
and
capacitors
typically
have
±10%
(–3 dB) frequency at 72 MHz and a –1-dB passband
tolerances. Using a Monte Carlo analysis shows that
typically at 60 MHz. This 72-MHz filter is ideal for
the filter corner frequency (–3 dB), flatness (–1 dB), Q
1080p50 or 1080p60 component video. It is also ideal
factor (or peaking), and channel-to-channel delay
for oversampling systems where the video DAC
have wide variations. These variances can lead to
upsamples the video signal such as 720p or 1080i
potential
performance
and
quality
issues
in
upsampled to 148.5 MHz. The benefit is an extremely
mass-production environments. The THS7364 solves
flat passband response along with almost no group
most of these problems with the corner frequency
delay within the HD video passband. In bypass mode,
being essentially the only variable.
these filters can also be used for some computer
Another concern about passive filters is the use of
R’G’B’ video signals including VGA, SVGA, XGA,
inductors. Inductors are magnetic components, and
SXGA, and QXGA.
are
therefore
susceptible
to
electromagnetic
Keep in mind that images do not stop at the DAC
coupling/interference
(EMC/EMI).
Some
common
sampling frequency, fS (for example, 27 MHz for
coupling can occur because of other video channels
traditional SD DACs); they continue around the
nearby using inductors for filtering, or it can come
sampling frequencies of 2x fS, 3x fS, 4x fS, and so on
from nearby switched-mode power supplies. Some
(that is, 54 MHz, 81 MHz, 108 MHz, etc.). Because of
other forms of coupling could be from outside sources
these multiple images, an ADC can fold down into the
with strong EMI radiation and can cause failure in
baseband signal, meaning that the low-pass filter
EMC testing such as required for CE compliance.
must also eliminate these higher-order images. The
One concern about an active filter in an integrated
THS7364 filters are Butterworth filters and, as such,
circuit is the variation of the filter characteristics when
do not bounce at higher frequencies, thus maintaining
the ambient temperature and the subsequent die
good attenuation performance.
temperature
changes.
To
minimize
temperature
The filter frequencies were chosen to account for
effects,
the
THS7364
uses
low-temperature
process variations in the THS7364. To ensure the
coefficient resistors and high-quality, low-temperature
required video frequencies are effectively passed, the
coefficient capacitors found in the BiCom3X process.
filter corner frequency must be high enough to allow
These filters have been specified by design to
component variations. The other consideration is that
account for process variations and temperature
the attenuation must be large enough to ensure the
variations to maintain proper filter characteristics.
anti-aliasing/reconstruction filtering is sufficient to
This approach maintains a low channel-to-channel
meet the system demands. Thus, the selection of the
time delay that is required for proper video signal
filter frequencies was not arbitrarily selected and is a
performance.
good compromise that should meet the demands of
Another benefit of the THS7364 over a passive RLC
most systems.
filter is the input and output impedance. The input
One of the features of the THS7364 is that these
impedance presented to the DAC varies significantly,
filters can be bypassed. Bypassing the SD filters
from 35
to over 1.5 k with a passive network, and
results in an amplifier with 150-MHz bandwidth and
may cause voltage variations over frequency. The
100-V/ms slew rate. This configuration can be helpful
THS7364 input impedance is 800 k
, and only the
when diagnosing potential system issues or when
2-pF
input
capacitance
plus
the
PCB
trace
simply wishing to pass higher frequency signals
capacitance impact the input impedance. As such,
through the system.
the voltage variation appearing at the DAC output is
better controlled with a fixed termination resistor and
Bypassing the FHD filters results in a amplifier
the high input impedance buffer of the THS7364.
supporting 350-MHz bandwidth and 500-V/ms slew
rate. This configuration supports computer R'G'B'
On the output side of the filter, a passive filter again
signals up to UWXGA resolution.
has a large impedance variation over frequency. The
EIA/CEA-770 specifications require the return loss to
be at least 25 dB over the video frequency range of
usage. For a video system, this requirement implies
the source impedance (which includes the source,
36
Copyright 2010, Texas Instruments Incorporated
Product Folder Link(s): THS7364
相關(guān)PDF資料
PDF描述
THS7364IPW 6 CHANNEL, VIDEO AMPLIFIER, PDSO20
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THS7365IPW 6 CHANNEL, VIDEO AMPLIFIER, PDSO20
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
THS7365 制造商:TI 制造商全稱(chēng):Texas Instruments 功能描述:6-Channel Video Amplifier with 3-SD and 3-HD Sixth-Order Filters and 6-dB Gain
THS7365EVM 功能描述:放大器 IC 開(kāi)發(fā)工具 THS7365EVM Eval Mod RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類(lèi)型:Power Amplifiers 工具用于評(píng)估:IR4302 工作電源電壓:13 V to 23 V
THS7365IPW 功能描述:視頻放大器 6Ch Video Amp RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類(lèi)型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel
THS7365IPWR 功能描述:視頻放大器 6Ch Video Amp RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類(lèi)型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel
THS7368 制造商:TI 制造商全稱(chēng):Texas Instruments 功能描述:6-Channel Video Amplifier with 3-SD and 3-SD/ED/HD/Full-HD Filters and 6-dB Gain
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