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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)： | 11/12頁 |
| 文件大?。?/td> | 212K |
| 代理商： | VCA610 |
VCA610
11
FIGURE 10. Signal Drive of the VCA610 Gain Control Pin
Produces and Exponential Response, Re-ex-
panding Signal Companded by Figure 9.
R
2
330
VCA610
R
1
470
V
O
= –V
R
10
–2 [R1 VIN /(R1 + R2) + 1]
V
IN
V
R
–10mV
V
C
FIGURE 11. This Voltage-Tuneable Low-Pass Filter Pro-
duces a Variable Cutoff Frequency with a
3,000:1 Range.
Finite loop gain and a signal swing limitation set perfor-
mance boundaries for the circuit. Both limitations occur
when the VCA610 attenuates rather than amplifies the
feedback signal. These two limitations reduce the circuit’s
utility at the lower extreme of the VCA610’s gain range. For
–1
≤
V
≤
0, this amplifier produces attenuating gains in the
range from 0dB to –40dB. This directly reduces the net gain
in the circuit’s feedback loop, increasing gain error effects.
Also, this attenuation transfers an output swing limitation
from the OPA620 output to the overall circuit’s output. Note
that OPA620 output voltage, V
, relates to V
through the
expression V
= GV
. Thus, a G < 1 limits the maximum
V
O
swing to a value less than the maximum V
OA
swing.
However, the circuit shown provides greater output swing
than the more common multiplier implementation. The latter
replaces the VCA610 of the figure with an analog multiplier
having a response of V
O
= XY/10. Then, X = V
OA
and Y =
V
C
, making the circuit output voltage V
O
= V
OA
V
C
/10. Thus,
the multiplier implementation amplifies V
OA
by a gain of V
C
/
10. Circuit constraints require that V
C
≤
10, making this gain
≤
1. Thus, the multiplier performs only as a variable attenu-
ator and never provides amplification. As a result, the
voltage swing limitation of V
OA
restricts the V
O
swing
throughout most of the circuit’s control range. Replacing the
multiplier with the VCA610 shown permits equivalent gains
greater > 1. Then, operating the VCA610 with gains in the
range of one to 100 avoids the reduction in output swing
capability.
VOLTAGE-CONTROLLED HIGH-PASS FILTER
A circuit analogous to the above low-pass filter produces a
voltage-controlled high-pass response. The gain control pro-
vided by the VCA610 of Figure 12 varies this circuit’s
response zero from 1Hz to 10kHz according to the relation-
ship F
Z
≈
1/2
π
GR
1
C where G = 10
–2 (V
C
+ 1)
.
f
P
= G/2
π
R
2
C G = 10
–2(V
C
+ 1)
V
O
V
I
= –
R
2
R
1
1
1 + R
2
Cs/G
VOLTAGE-CONTROLLED LOW-PASS FILTER
In the circuit of Figure 11, the VCA610 serves as the
variable gain element of a voltage-controlled low-pass filter.
As will be described, this implementation expands the circuit’s
voltage swing capability over that normally achieved with
the equivalent multiplier implementation. The circuit’s re-
sponse pole responds to control voltage V
C
according to the
relationship f
= G/2
π
R
C where G = 10
–2 (V
C
+ 1)
. With the
components shown, the circuit provides a linear variation of
the low-pass cutoff from 300Hz to 1MHz.
FIGURE 12. A Voltage-Tunable High-Pass Filter Pro-
duces a Response Zero Variable from 1Hz to
10kHz.
The response control results from amplification of the feed-
back voltage applied to R
. Consider first the case where the
VCA610 produces G = 1. Then, the circuit performs as if
this amplifier were replaced by a short circuit. Visually
doing so leaves a simple voltage amplifier with a feedback
resistor bypassed by a capacitor. This basic circuit produces
a response pole at f
P
= 1/2
π
R
2
C.
For G > 1, the circuit applies a greater voltage to R
2
,
increasing the feedback current this resistor supplies to the
summing junction of the OPA620. The increased feedback
current produces the same result as if R
2
had been decreased
in value in the basic circuit described above. Decreasing the
effective R
2
resistance moves the circuit’s pole to a higher
frequency, producing the f
P
= G/2
π
R
2
C response control.
OPA620
VCA610
V
C
V
O
V
OA
0.047μF
330
R
2
330
R
1
C
V
I
OPA620
VCA610
V
C
0.047μF
V
OA
C
R
3
33
V
O
R
2
33k
R
1
33k
V
I
For R
3
<< GR
1
and f << 1/2
π
R
3
Cs,
V
O
V
I
R
1
where G = 10
–2(VC + 1)
R
2
(1 + GR
1
Cs), f
Z
= 1/2
π
GR
1
C
= –
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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