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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(yè)數(shù)： | 7/12頁(yè) |
| 文件大?。?/td> | 212K |
| 代理商： | VCA610 |
VCA610
7
when either the maximum output voltage swing or output
current is exceeded. The VCA610’s high output current of
±
80mA insures that virtually all output overloads will be
limited by voltage swing rather than by current limiting. At
G = +40dB, 1dBm compression occurs when the output
voltage approaches 3Vp-p (3.5dBm for R
L
= 500
). Table
I below summarizes these results.
one selected gain. Selecting the maximum gain optimizes
offset performance for higher gains where high amplifica-
tion of the offset effects produces the greatest output offset.
Two features minimize the offset control circuit’s noise
contribution to the amplifier input circuit. First, making the
resistance of R
2
a low value minimizes the noise directly
introduced by the control circuit. This reduces both the
thermal noise of the resistor and the noise produced by the
resistor with the amplifier’s input noise current. A second
noise reduction results from capacitive bypass of the poten-
tiometer output. This filters out power supply noise that
would otherwise couple to the amplifier input.
This filtering action would diminish as the wiper position
approaches either end of the potentiometer but practical
conditions prevent such settings. Over its full adjustment
range, the offset control circuit produces a
±
5mV offset
correction for the values shown. However, the VCA610 only
requires one tenth of this range for offset correction, assur-
ing that the potentiometer wiper will always be near the
potentiometer center. With this setting, the resistance seen at
the wiper remains high and this stabilizes the filtering
function.
GAIN CONTROL
The VCA610’s gain is controlled by means of a unipolar
negative voltage applied between ground and the gain con-
trol input, pin 3. If use of the output disable feature is
required, a ground-referenced bipolar voltage is needed.
Output disable occurs for +0.1V
≤
V
C
≤
+2V, and produces
80dB of attenuation. The control voltage should be limited
to +2V in disable mode, and –2V in the gain mode in order
to prevent saturation of internal circuitry.
FIGURE 3. Optional Offset Adjustment and Control Line
Filtering.
3a) Optional Offset Adjustment.
3b) Control Line Filtering.
VCA610
1μF
V
C
V–
V
IN
V
O
R
V
100k
R
2
10
V+
R
1
10k
VCA610
V
O
R
P
Cp
f
–3dB
= 2
π
Rp Cp
V
C
WIRING PRECAUTIONS
Maximizing the VCA610’s capability requires some wiring
precautions and high-frequency layout techniques. In gen-
eral, printed circuit board conductors should be as short and
as wide as possible to provide low resistance, low imped-
ance signal paths. Stray signal coupling from the output or
power supplies to the inputs should be minimized. Unused
inputs should be grounded as close to the package as
possible.
Low impedance ground returns for signal and power are
essential. Proper supply bypassing is also extremely critical
and must
always
be used. Both power supply leads should be
bypassed to ground as close as possible to the amplifier pins.
Tantalum capacitors (1
μ
F to 10
μ
F) with very short leads are
recommended. Surface mount bypass capacitors will pro-
vide excellent results due to their low lead inductance.
OVERLOAD RECOVERY
As shown in Figure 2, the onset of overload occurs when-
ever the actual output begins to deviate from the ideal
expected output. If possible, the user should operate the
VCA610 within the linear regions shown in order to mini-
mize signal distortion and overload delay time. However,
instances of amplifier overload are actually quite common in
Automatic Gain Control (AGC) circuits which involve the
application of variable gain to signals of varying levels. The
VCA610’s design incorporates circuitry which allows it to
recover from most overload conditions in 200ns or less.
Overload recovery time is defined as the time required for
the output to return from overload to linear operation follow-
ing the removal of either an input or gain control overdrive
signal.
OFFSET ADJUSTMENT
Where desired, the offset of the VCA610 can be removed as
shown in Figure 3. This circuit simply presents a DC voltage
to one of the amplifier’s inputs to counteract the offset error
voltage. For best offset performance, the trim adjustment
should be made with the amplifier set at the maximum gain
of the intended application. The offset voltage of the VCA610
varies with gain, limiting the complete offset cancellation to
OUTPUT COMPRESSION
MECHANISM
TO PREVENT
OPERATE WITHIN
GAIN RANGE
–40dB < G < –5dB
Input Stage Overload
Input Voltage Range
–5dB < G < +5dB
Internal Stages Overloading Output Voltage Range
+5dB < G < +40dB
Output Stage Overload
Output Voltage Range
TABLE I. Output Signal Compression.
相關(guān)PDF資料 |
PDF描述 |
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| 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(yè)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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