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參數資料
| 型號： | VCA810AIDR |
| 英文描述： | High Gain Adjust Range, Wideband, Voltage-Controlled Amplifier |
| 中文描述： | 高增益調整范圍，寬帶，電壓控制放大器 |
| 文件頁數： | 12/25頁 |
| 文件大?。?/td> | 417K |
| 代理商： | VCA810AIDR |
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SBOS275C JUNE 2003 REVISED OCTOBER 2004
www.ti.com
12
RANGE FINDING TGC AMPLIFIER
The block diagram in Figure 3 illustrates the fundamental
configuration common to pulse-echo range finding
systems. A photodiode preamp provides an initial gain
stage to the photodiode.
VCA810
V
C
V
C
20
20
ADC
andDSP
t
0
2V
TimeGain Compensated Control Voltage
OPA657
V
B
20k
C
F
Figure 3. Typical Range Finding Application
The control voltage V
C
varies the amplifier gain for a basic
signal-processing requirement: compensation for
distance attenuation effects, sometimes called Time-Gain
Compensation (TGC). Time-gain compensation increases
the amplifier gain as the signal moves through the air to
compensate for signal attenuation. For this purpose, a
ramp signal applied to the VCA810 gain control input
linearly increases the dB gain of the VCA810 with time.
WIDE-RANGE AGC AMPLIFIER
The voltage-controlled gain feature of the VCA810 makes
this amplifier ideal for precision AGC applications with
control ranges as large as 60dB. The AGC circuit of
Figure 4 adds an op amp and diode for amplitude
detection, a hold capacitor to store the control voltage and
resistors R
1
through R
3
that determine attack and release
times. Resistor R
4
and capacitor C
C
phase compensate
the AGC feedback loop. The op amp compares the
positive peaks of output V
O
with a DC reference voltage,
V
R
. Whenever a V
O
peak exceeds V
R
, the OPA820 output
swings positive, forward-biasing the diode and charging
the holding capacitor. This charge drives the capacitor
voltage in a positive direction, reducing the amplifier gain.
R
3
and the C
H
largely determine the attack time of this
AGC correction.
Between gain corrections, resistor R
1
charges the
capacitor in a negative direction, increasing the amplifier
gain. R
1
, R
2
, and C
H
determine the release time of this
action. Resistor R
2
forms a voltage divider with R
1
, limiting
the maximum negative voltage developed on C
H
. This limit
prevents input overload of the VCA810 gain control circuit.
Figure 5 shows the AGC response for the values shown in
Figure 4.
VCA810
C
H
0.1
μ
F
V
V
IN
OPA820
V
R
V
OUT PEAK
= V
R
V
O
R
3
1k
HP5082
R
1
50k
2mVto2V
100kHz
RSSI
Port
R
2
50k
C
47pF
0.1 VDC
R
4
100
V
C
Figure 4. 60dB Input Range AGC
0.15
0.10
0.05
0
0.05
0.10
0.15
0.20
Time (5
μ
s/div)
O
V
IN
= 10mV
PP
V
IN
= 100mV
PP
V
IN
= 1V
PP
Figure 5. AGC Output Voltage for 100kHz
Sinewave at 10mV
PP
, 100mV
PP
and 1V
PP
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相關代理商/技術參數 |
參數描述 |
|---|---|
| VCA810AIDRG4 | 功能描述:特殊用途放大器 High-Gain Adj Range Wideband Vltg-Cntrl RoHS:否 制造商:Texas Instruments 通道數量:Single 共模抑制比（最小值）: 輸入補償電壓: 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 安裝風格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| VCA810ID | 功能描述:特殊用途放大器 High-Gain Adj Range Wideband Vltg-Cntrl RoHS:否 制造商:Texas Instruments 通道數量:Single 共模抑制比（最小值）: 輸入補償電壓: 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 安裝風格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| VCA810IDG4 | 功能描述:特殊用途放大器 High-Gain Adj Range Wideband Vltg-Cntrl RoHS:否 制造商:Texas Instruments 通道數量:Single 共模抑制比（最小值）: 輸入補償電壓: 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 安裝風格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| VCA810IDR | 功能描述:特殊用途放大器 High-Gain Adj Range Wideband Vltg-Cntrl RoHS:否 制造商:Texas Instruments 通道數量:Single 共模抑制比（最小值）: 輸入補償電壓: 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 安裝風格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| VCA810IDRG4 | 功能描述:特殊用途放大器 High-Gain Adj Range Wideband Vltg-Cntrl RoHS:否 制造商:Texas Instruments 通道數量:Single 共模抑制比（最小值）: 輸入補償電壓: 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 安裝風格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
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