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參數(shù)資料
| 型號： | VCA8613YR |
| 廠商： | Texas Instruments, Inc. |
| 元件分類： | 可變增益放大器 |
| 英文描述： | 8-Channel VARIABLE GAIN AMPLIFIER |
| 中文描述： | 8通道可變增益放大器 |
| 文件頁數(shù)： | 13/21頁 |
| 文件大?。?/td> | 378K |
| 代理商： | VCA8613YR |
VCA8613
SBOS200C
13
www.ti.com
TYPICAL CHARACTERISTICS
(Cont.)
At T
A
= +25
°
C, f
IN
= 2MHz, AT
N
= 00, PG = 01, V
CNTRL
= 1.7V, unless otherwise noted. Differential output, 750mV
PP
, and AV
DD
= DV
DD
= 3.0V.
OVERLOAD RECOVERY vs TIME
(ATN = 00, PG = 00, V
CNTRL
= 1V)
Time (400ns/div)
The signal is greater than 2V
input, so the LNA is
severely overloaded. Overload recovery time is 192ns.
Channel 1
(Output)
(2V/div)
Channel 2
(Input)
(1V/div)
OVERLOAD RECOVERY vs TIME
(ATN = 00, PG = 01, V
CNTRL
= 2V)
Time (400ns/div)
The signal is greater than 40mV
PP
input, so the LNA is in the linear region
and the output amplifier is overloaded. Overload recovery time is 584ns.
Channel 1
(Output)
(2V/div)
Channel 2
(Input)
(20mV/div)
APPLICATION INFORMATION
INPUT CIRCUIT
The input of the VCA8613 integrates several commonly used
elements. Prior to reaching the input of the VCA, the receive
signal should be coupled with a capacitor of at least 1nF,
preferably more. When this AC coupling element is inserted,
the LNA input bias point is held to a common-mode value of
2.4V by an integrated 4.5k
resistor. This common-mode
value will change with temperature and may also vary from
chip to chip, but for each chip, it will be held constant. In
parallel with this resistor are two back-to-back clipping di-
odes. These diodes prevent excessive input voltages from
passing through to the LNA input, preventing deep saturation
effects in the LNA itself.
LOW-NOISE PRE-AMPLIFIER (LNA)
The VCA8613 integrates a low-noise pre-amplifier. Because
of the high level of integration in the system, noise perfor-
mance was traded for power consumption, resulting in an
extremely low-power pre-amplifier, with 1.2nV/
√
Hz
noise
performance at 5MHz. The LNA is configured as a fixed-gain
25dB amplifier. Of this total gain, 6dB results from the single-
ended to differential conversion accomplished within the LNA
itself. The output of the LNA is limited to a little over 2V
differential swing. This implies a maximum input voltage
swing of approximately 110mV to be operating in the linear
range at 5MHz. Larger input signals can be accepted by the
LNA, but distortion performance will degrade with high-level
input signals.
CW DOPPLER PROCESSOR
The VCA8613 integrates many of the elements necessary to
allow for the implementation of a simple CW Doppler pro-
cessing circuit. One circuit that was integrated was a V/I
converter following the LNA (see Figure 1). The V/I converter
converts the LNA voltage output to a current which is then
passed through an 8x10 switch matrix (see Figure 2). Within
this switch matrix, any of the eight LNA outputs can be
connected to any of ten CW output pins. This is a simple
current-summing circuit such that each CW output can rep-
resent the sum of any or all the channel currents. The output
current for each LNA is equal to the single-ended LNA output
voltage swing divided by an internally integrated 700
resis-
tor. This resistor value may change
±
5% from chip to chip.
The CW output pins need a compliance voltage between 3V
to 3.3V. The 3V to 3.3V can be applied through either an
inductor (see Figure 3) tied to the 3V to 3.3V source or from
the inverting input of an op amp circuit (see Figure 4). The
architecture of the V/I converter requires a 2mA to 2.5mA
current that is generated by the compliance voltage.
The CW outputs are typically routed to a passive delay line,
allowing coherent summing of the signals. After summing, IQ
separation and down conversion to base-band precedes a
pair of high-resolution, low sample rate ADCs.
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| VCA8613YT | 功能描述:特殊用途放大器 8-Channel Variable Gain Amplifier RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補(bǔ)償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| VCA8616PAGT | 制造商:Texas Instruments 功能描述: |
| VCA8617 | 制造商:BB 制造商全稱:BB 功能描述:8-Channel VARIABLE GAIN AMPLIFIER |
| VCA8617PAGR | 功能描述:特殊用途放大器 8-Channel Variable Gain Amplifier RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補(bǔ)償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| VCA8617PAGRG4 | 功能描述:特殊用途放大器 8-Channel Variable Gain Amplifier RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補(bǔ)償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
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