參數(shù)資料
型號(hào): VCA2616
英文描述: Dual, Variable-Gain Amplifier with Low-Noise Preamp
中文描述: 雙路,可變?cè)鲆娣糯笃鞯牡驮肼暻爸梅糯笃?/td>
文件頁(yè)數(shù): 16/19頁(yè)
文件大?。?/td> 389K
代理商: VCA2616
VCA2616, VCA2611
SBOS234E
16
www.ti.com
FIGURE 15. Simplified Block Diagram of the PGA Section Within the VCA2616 and VCA2611.
R
S1
R
L
R
S2
VCA
OUT
P
+In
Q
11
Q
3
Q
4
Q
5
Q
1
V
CM
Q
2
VCA
OUT
N
Q
9
Q
8
Q
13
Q
14
Q
7
Q
6
Q
12
V
DD
V
CM
R
L
Q
10
In
To Bias
Circuitry
To Bias
Circuitry
R
F
C
F
V
DD
LNP
IN
P
ESD Diode
Protection
Network
LNP
OUT
N
LNP
FIGURE 14. VCA2616 and VCA2611 Diode Bridge Protection
Circuit.
To prevent damage, it is necessary to place a protection circuit
between the transducer and the VCA2616 and VCA2611 (see
Figure 14). Care must be taken to prevent any signal from
turning the ESD diodes on. Turning on the ESD diodes inside
the VCA2616 and VCA2611 could cause the input coupling
capacitor (C
C
) to charge to the wrong value.
PGA POST-AMPLIFIER
DETAIL
Figure 15 shows a simplified circuit diagram of the PGA block.
As described previously, the PGA gain is programmed with
the same MGS bits which control the VCA maximum attenu-
ation factor. Specifically, the PGA gain at each MGS setting is
the inverse (reciprocal) of the maximum VCA attenuation at
that setting. Therefore, the VCA + PGA overall gain will always
be 0dB (unity) when the analog VCA
CNTL
input is set to 0V
MGS
SETTING
ATTENUATOR GAIN
VCA
CNTL
= 0V to 3V
DIFFERENTIAL
PGA GAIN
ATTENUATOR +
DIFF. PGA GAIN
000
001
010
011
100
101
110
111
24dB to 0dB
27dB to 0dB
30dB to 0dB
33dB to 0dB
36dB to 0dB
39dB to 0dB
42dB to 0dB
45dB to 0dB
24dB
27dB
30dB
33dB
36dB
39dB
42dB
45dB
0dB to 24dB
0dB to 27dB
0dB to 30dB
0dB to 33dB
0dB to 36dB
0dB to 39dB
0dB to 42dB
0dB to 45dB
TABLE III. MGS Settings.
(= maximum attenuation). For VCA
CNTL
= 3V (no attenuation),
the VCA + PGA gain will be controlled by the programmed
PGA gain (24 to 45 dB in 3dB steps). For clarity, the gain and
attenuation factors are detailed in Table III.
The PGA architecture consists of a differential, program-
mable-gain voltage to current converter stage followed by
transimpedance amplifiers to create and buffer each side of
the differential output. The circuitry associated with the volt-
age to current converter is similar to that previously de-
scribed for the LNP, with the addition of eight selectable PGA
gain-setting resistor combinations (controlled by the MGS
bits) in place of the fixed resistor network used in the LNP.
Low input noise is also a requirement of the PGA design due
to the large amount of signal attenuation which can be
inserted between the LNP and the PGA. At minimum VCA
attenuation (used for small input signals) the LNP noise
dominates; at maximum VCA attenuation (large input sig-
nals) the PGA noise dominates. Note that if the PGA output
is used single-ended, the apparent gain will be 6dB lower.
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VCA2616YT 功能描述:特殊用途放大器 Dual Variable Gain RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比(最小值): 輸入補(bǔ)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(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel
VCA2617 制造商:BB 制造商全稱:BB 功能描述:Dual, Variable Gain Amplifier
VCA2617EVM 功能描述:放大器 IC 開(kāi)發(fā)工具 VCA2617 Eval Mod RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類型:Power Amplifiers 工具用于評(píng)估:IR4302 工作電源電壓:13 V to 23 V