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參數(shù)資料
| 型號(hào)： | VCA610 |
| 英文描述： | WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| 中文描述： | 寬帶電壓控制放大器 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 212K |
| 代理商： | VCA610 |
VCA610
8
The VCA610’s gain control input has a –3dB bandwidth of
1MHz and varies with frequency as shown in the Typical
Performance Curves. This wide bandwidth, although useful
for many applications, can allow high frequency noise to
modulate the gain control input. In practice, this can be
easily avoided by filtering the control input as shown in
Figure 3b. R
P
should be no greater than 100
so as not to
introduce gain errors by interacting with the gain control’s
input bias current of 2
μ
A.
INPUT PROTECTION
Electrostatic damage (ESD) has been well recognized for
MOSFET devices, but any semiconductor device deserves
protection from this potentially damaging source. The
VCA610 incorporates on-chip ESD protection diodes as
shown in Figure 4. This eliminates the need for the user to
add external protection diodes, which can add capacitance
and degrade AC performance.
ULTRASOUND TGC AMPLIFIER
The Figure 5 block diagram illustrates the fundamental
configuration common to pulse-echo imaging systems. A
piezoelectric crystal serves as both the ultrasonic pulse
generator and the echo monitor transducer. A transmit/
receive (T/R) switch isolates the monitor amplifier from the
crystal during the pulse generation cycle and, then, connects
the amplifier to the crystal during the echo monitor cycle.
FIGURE 4. Internal ESD Protection.
External
Pin
+V
S
–V
S
Internal
Circuitry
ESD Protection diodes internally
connected to all pins.
All pins on the VCA610 are internally protected from ESD
by means of a pair of back-to-back reverse-biased diodes to
either power supply as shown. These diodes will begin to
conduct when the pin voltage exceeds either power supply
by about 0.7V. This situation can occur with loss of the
amplifier’s power supplies while a signal source is still
present. The diodes can typically withstand a continuous
current of 30mA without destruction. To insure long term
reliability, however, diode current should be externally lim-
ited to 10mA whenever possible.
The internal protection diodes are designed to withstand
2.5kV (using Human Body Model) and provides adequate
ESD protection for most normal handling procedures. How-
ever, static protection is strongly recommended since static
damage can cause subtle changes in amplifier operational
characteristics without necessarily destroying the device.
APPLICATIONS
The electronically variable gain of the VCA610 suits pulse-
echo imaging systems well. Such applications include medical
imaging, non-destructive structural inspection and optical
distance measurement. The amplifier’s variable gain also
serves AGC amplifiers, amplitude-stabilized oscillators,
log amplifiers and exponential amplifiers. The discussions
below present examples of these applications.
FIGURE 5. Typical Ultrasound Application.
VCA610
V
C
V
C
Transducer
ADC
& DSP
t
0
–2V
T/R
Switch
Transmit
Receive
During the monitor (receive) cycle, the control voltage V
C
,
varies the amplifier gain. The gain is varied for three basic
signal processing requirements of a transducer array based
beamformer: compensation for depth attenuation effects,
sometimes called Time Gain Compensation (TGC); receive
apodization or windowing for reducing side lobe energy;
and dynamic aperture sizing for better near field resolution.
Time gain compensation increases the amplifier’s gain as
the ultrasound signal moves through the material to compen-
sate for signal attenuation versus material depth. For this
purpose, a ramp signal applied to the VCA610 gain control
input linearly increases the dB gain of the VCA610 with
time. The gain control provides signal apodization or
windowing with transducer arrays connected to amplifier
arrays. Selective weighting of amplifier gains across the
transducer aperture suppresses side lobe effects in the
beamformer output to reduce image artifacts. Gain con-
trolled attenuation or disabling the amplifier can be used to
dynamically size the array aperture for better near field
resolution. The controlled attenuation of the VCA610 mini-
mizes switching artifacts and eliminates the bright radial
rings that can result. The VCA610’s 80dB gain range ac-
commodates these functions.
WIDE-RANGE LOW-NOISE VCA
Figure 6 combines two VCA610s in series, extending the
overall gain range and improving noise performance. This
combination produces a gain equal to the sum of the two
amplifier’s logarithmic gains for a composite range of
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| VCA610P | WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA610PA | WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA610U | WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA610UA | WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA810 | High Gain Adjust Range, Wideband, Voltage-Controlled Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| VCA610P | 制造商:BB 制造商全稱:BB 功能描述:WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA610PA | 制造商:BB 制造商全稱:BB 功能描述:WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA610U | 功能描述:IC OPAMP VGA R-R 30MHZ SGL 8SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 產(chǎn)品變化通告:Discontinuation 18/May/2012 標(biāo)準(zhǔn)包裝:2,000 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:滿擺幅 轉(zhuǎn)換速率:0.42 V/µs 增益帶寬積:1.5MHz -3db帶寬:- 電流 - 輸入偏壓:15nA 電壓 - 輸入偏移:1000µV 電流 - 電源:116µA 電流 - 輸出 / 通道:100mA 電壓 - 電源，單路/雙路(±):1.8 V ~ 5 V，±0.9 V ~ 2.5 V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:14-TSSOP 包裝:帶卷 (TR) 產(chǎn)品目錄頁面:851 (CN2011-ZH PDF) 其它名稱:296-20930-2 |
| VCA610UA | 制造商:BB 制造商全稱:BB 功能描述:WIDEBAND VOLTAGE CONTROLLED AMPLIFIER |
| VCA-6303 | 制造商:Quest Technology International Inc 功能描述: |
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