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參數資料
| 型號： | AD605BRZ |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 模擬信號調理 |
| 英文描述： | Dual, Low Noise, Single-Supply Variable Gain Amplifier |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO16 |
| 封裝： | LEAD FREE, MS-012-AC, SOIC-16 |
| 文件頁數： | 15/20頁 |
| 文件大?。?/td> | 278K |
| 代理商： | AD605BRZ |
AD605
Rev. D | Page 15 of 20
35
30
25
20
15
10
5
0
–5
–10
–15
–20
G
40dB/V
30dB/V
20dB/V
LINEAR-IN-dB RANGE
OF AD605
1.0
0.5
1.5
2.0
2.5
3.0
GAIN CONTROL VOLTAGE
0
Figure 37. Ideal Gain Curves vs. V
REF
Usable gain control voltage ranges are 0.1 V to 2.9 V for the
20 dB/V scale and 0.1 V to 1.45 V for the 40 dB/V scale. VGN
voltages of less than 0.1 V are not used for gain control because
below 50 mV the channel is powered down. This can be used to
conserve power and at the same time gate-off the signal. The
supply current for a powered-down channel is 1.9 mA, and the
response time to power the device on or off is less than 1 μs.
ACTIVE FEEDBACK AMPLIFIER (FIXED GAIN AMP)
To achieve single-supply operation and a fully differential input
to the DSX, an active feedback amplifier (AFA) was used. The
AFA is an op amp with
two
g
m
stages; one of the active stages is
used in the feedback path (therefore the name), while the other
is used as a differential input. Note that the differential input is
an open-loop g
m
stage that requires that it be highly linear over
the expected input signal range. In this design, the g
m
stage that
senses the voltages on the attenuator is a distributed one; for
example, there are as many g
m
stages as there are taps on the
ladder network. Only a few of them are on at any one time,
depending on the gain control voltage.
The AFA makes a differential input structure possible since one
of its inputs (G1) is fully differential; this input is made up of a
distributed g
m
stage. The second input (G2) is used for feedback.
The output of G1 is some function of the voltages sensed on the
attenuator taps that is applied to a high-gain amplifier (A0).
Because of negative feedback, the differential input to the high
gain amplifier is zero; this in turn implies that the differential
input voltage to G2 times g
m2
(the transconductance of G2) is
equal to the differential input voltage to G1 times g
m1
(the
transconductance of G1). Therefore the overall gain function
of the AFA is
×
×
=
2
2
1
2
1
R
R
R
gm
gm
V
V
ATTEN
OUT
(7)
where:
V
OUT
is the output voltage.
V
ATTEN
is the effective voltage sensed on the attenuator.
(
R1
+
R2
)/
R2
= 42.
g
m1
/
g
m2
= 1.25; the overall gain is therefore 52.5 (34.4 dB).
The AFA has additional features: inverting the output signal by
switching the positive and negative input to the ladder network;
the possibility of using the IN input as a second signal input;
and independent control of the DSX common-mode voltage.
Under normal operating conditions, it is best to connect a
decoupling capacitor to Pin VOCM, in which case, the common-
mode voltage of the DSX is half of the supply voltage; this allows
for maximum signal swing. Nevertheless, the common-mode
voltage can be shifted up or down by directly applying a voltage
to VOCM. It can also be used as another signal input, the only
limitation being the rather low slew rate of the VOCM buffer.
If the dc level of the output signal is not critical, another
coupling capacitor is normally used at the output of the DSX;
again, this is done for level shifting and to eliminate any dc
offsets contributed by the DSX (see the AC Coupling section).
The gain range of the DSX is programmable by a resistor
connected between Pin FBK and Pin OUT. The possible ranges
are 14 dB to +34.4 dB when the pins are shorted together, or
0 dB to +48.4 dB when FBK is left open. Note that for the
higher gain range, the bandwidth of the amplifier is reduced by
a factor of five to about 8 MHz because the gain increased by
14 dB. This is the case for any constant gain bandwidth product
amplifier that includes the active feedback amplifier.
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| AD605-EB | Dual, Low Noise, Single-Supply Variable Gain Amplifier |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD605BRZ-R7 | 功能描述:IC AMP VGA DUAL LN 40MA 16SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:X-AMP® 標準包裝:50 系列:- 放大器類型:J-FET 電路數:2 輸出類型:- 轉換速率:3.5 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:30pA 電壓 - 輸入偏移:2000µV 電流 - 電源:200µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應商設備封裝:8-PDIP 包裝:管件 |
| AD605BRZ-RL | 功能描述:IC AMP VGA DUAL LN 40MA 16SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:X-AMP® 標準包裝:50 系列:- 放大器類型:J-FET 電路數:2 輸出類型:- 轉換速率:3.5 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:30pA 電壓 - 輸入偏移:2000µV 電流 - 電源:200µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應商設備封裝:8-PDIP 包裝:管件 |
| AD605BRZ-RL7 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dual, Low Noise, Single-Supply Variable Gain Amplifier |
| AD605-EB | 制造商:Analog Devices 功能描述: |
| AD605EHDK42GMS | 制造商:Advanced Micro Devices 功能描述:EB E64 4C 605E AM3 45W - Trays |
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