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型号： THS3201MDGNEP
厂商： TEXAS INSTRUMENTS INC
元件分类： 音频／视频放大
英文描述： 1 CHANNEL, VIDEO AMPLIFIER, PDSO8
封装： PLASTIC, MSOP-8
文件页数： 14/29页
文件大小： 709K
代理商： THS3201MDGNEP
Printed-Circuit Board Layout Techniques for
THS3201-EP
www.ti.com ..................................................................................................................................................... SGLS283B – APRIL 2005 – REVISED JANUARY 2009
resistors, excessively high resistor values can
Optimal Performance
create significant time constants that can degrade
performance.
Good
axial
metal-film
or
Achieving optimum performance with high-frequency
surface-mount
resistors
have
approximately
amplifier-like devices in the THS3201 requires careful
0.2 pF in shunt with the resistor. For resistor
attention to board layout parasitic and external
values >2 k
, this parasitic capacitance can add a
component types.
pole and/or a zero that can effect circuit operation.
Keep
resistor
values
as
low
as
possible,
Recommendations that optimize performance include:
consistent with load driving considerations.
Minimize parasitic capacitance to any power or
Connections to other wideband devices on the
ground plane for the negative input and ouput pins
board may be made with short direct traces or
by voiding the area directly below these pins and
through onboard transmission lines. For short
connecting
traces
and
the
feedback
path.
connections, consider the trace and the input to
Parasitic capacitance on the output and negative
the next device as a lumped capacitive load.
input
pins
can
cause
instability.
To
reduce
Relatively wide traces (50 mils to 100 mils) should
unwanted capacitance, a window around the
be used, preferably with ground and power planes
signal I/O pins should be opened in all of the
opened up around them. Estimate the total
ground and power planes around those pins and
capacitive load and determine if isolation resistors
the feedback path. Otherwise, ground and power
on the outputs are necessary. Low parasitic
planes should be unbroken elsewhere on the
capacitive loads (<4 pF) may not need an RS
board.
since the THS3201 is nominally compensated to
Minimize the distance (<0.25 in) from the
operate with a 2-pF parasitic load. Higher parasitic
power-supply pins to high frequency 0.1-F and
capacitive loads without an RS are allowed as the
100-pF decoupling capacitors. At the device pins,
signal gain increases (increasing the unloaded
the ground and power-plane layout should not be
phase margin). If a long trace is required and the
in close proximity to the signal I/O pins. Avoid
6-dB signal loss intrinsic to a doubly-terminated
narrow power and ground traces to minimize
transmission line is acceptable, implement a
inductance between the pins and the decoupling
matched
impedance
transmission
line
using
capacitors. The power-supply connections should
microstrip or stripline techniques (consult an ECL
always
be
decoupled
with
these
capacitors.
design handbook for these techniques).
Larger (6.8 F or more) tantalum decoupling
A 50- environment is not necessary onboard
capacitors, effective at lower frequency, should
and, in fact, a higher-impedance environment
also be used on the main supply pins. These may
improves distortion as shown in the distortion
be placed somewhat farther from the device and
versus load plots. With a characteristic board
may be shared among several devices in the
trace impedance based on board material and
same area of the PC board. The primary goal is to
trace dimensions, a matching series resistor into
minimize
the
impedance
seen
in
the
the trace from the output of the THS3201 is used,
differential-current
return
paths.
For
driving
as well as a terminating shunt resistor at the input
differential loads with the THS3201, adding a
of the destination device.
capacitor
between
the
power-supply
pins
improves
2nd
order
harmonic
distortion
Remember also that the terminating impedance is
performance. This also minimizes the current loop
the parallel combination of the shunt resistor and
formed by the differential drive.
the input impedance of the destination device; this
total effective impedance should be set to match
Careful selection and placement of external
the trace impedance. If the 6-dB attenuation of a
components
preserve
the
high
frequency
doubly-terminated
transmission
line
is
performance of the THS3201. Resistors should be
unacceptable,
a
long
trace
can
be
a low-reactance type. Surface-mount resistors
series-terminated at the source end only. Treat
work best and allow a tighter overall layout. Again,
the trace as a capacitive load in this case. This
keep their leads and PC board trace length as
does not preserve signal integrity as well as a
short as possible. Never use wirebound-type
doubly-terminated line. If the input impedance of
resistors in a high-frequency application. Since the
the destination device is low, there is some signal
output pin and inverting input pins are the most
attenuation due to the voltage divider formed by
sensitive to parasitic capacitance, always position
the series output into the terminating impedance.
the feedback and series output resistors, if any, as
close as possible to the inverting input pins and
Socketing a high-speed part such as the THS3201
output pins. Other network components, such as
is not recommended. The additional lead length
input termination resistors, should be placed close
and pin-to-pin capacitance introduced by the
to
the
gain-setting
resistors.
Even
with
a
socket can create an extremely troublesome
low-parasitic capacitance shunting the external
parasitic network, which can make it almost
Copyright 2005–2009, Texas Instruments Incorporated
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Product Folder Link(s): THS3201-EP
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相关代理商/技术参数
参数描述
THS3201MDGNEP(1) 制造商:TI 制造商全称:Texas Instruments 功能描述:1.8-GHz LOW-DISTORTION CURRENT-FEEDBACK AMPLIFIER
THS3201MDGNREP 功能描述:高速运算放大器 Mil Enhance 1.8GHz Feedback Amp RoHS:否 制造商:Texas Instruments 通道数量:1 电压增益 dB:116 dB 输入补偿电压:0.5 mV 转换速度:55 V/us 工作电源电压:36 V 电源电流:7.5 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube
THS3201MDREP(1) 制造商:TI 制造商全称:Texas Instruments 功能描述:1.8-GHz LOW-DISTORTION CURRENT-FEEDBACK AMPLIFIER
THS3202 制造商:TI 制造商全称:Texas Instruments 功能描述:LOW-DISTORTION HIGH-SPEED VOLTAGE FEEDBACK AMPLIFIER
THS3202D 功能描述:高速运算放大器 2GHz Current Feedback Amplifier RoHS:否 制造商:Texas Instruments 通道数量:1 电压增益 dB:116 dB 输入补偿电压:0.5 mV 转换速度:55 V/us 工作电源电压:36 V 电源电流:7.5 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube
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