VCA2619YR [BB]
Dual, Variable Gain Amplifier with Input Buffer; 双可变增益放大器，具有输入缓冲器
| 型号： | VCA2619YR |
| 厂家： | 
BURR-BROWN CORPORATION |
| 描述： | Dual, Variable Gain Amplifier with Input Buffer |
| 文件： | 总16页 (文件大小：314K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
VCA2619
SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
Dual, Variable Gain Amplifier
with Input Buffer
FEATURES
DESCRIPTION
The VCA2619 is a highly integrated, dual receive channel,
Variable Gain Amplifier (VGA) with analog gain control.
D
D
GAIN RANGE: 50dB
LOW CROSSTALK: - 60dB at Max Gain,
= 5MHz
The VCA2619s VGA section consists of two parts: the
Voltage Controlled Attenuator (VCA) and the Programmable
Gain Amplifier (PGA). The gain and gain range of the PGA
can be digitally programmed. The combination of these two
programmable elements results in a variable gain ranging
from 0dB up to a maximum gain as defined by the user
through external connections. The single−ended unity gain
input buffer provides predictable high input impedance. The
output of the VGA can be used in either a single−ended or
differential mode to drive high−performance Analog−to−
Digital (A/D) converters. A separate power−down pin
reduces power consumption.
f
IN
D
D
D
HIGH−SPEED VARIABLE GAIN ADJUST
POWER SHUTDOWN MODE
HIGH IMPEDANCE INPUT BUFFER
APPLICATIONS
D
D
D
D
ULTRASOUND SYSTEMS
WIRELESS RECEIVERS
TEST EQUIPMENT
RADAR
The VCA2619 also features low crosstalk and outstanding
distortion performance. The combination of low noise and
gain range programmability make the VCA2619 a versatile
building block in a number of applications where noise
performance is critical. The VCA2619 is available in a
TQFP−32 package.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
ꢀꢁ ꢂ ꢃꢄ ꢅ ꢆꢇ ꢂꢈ ꢃ ꢉꢆꢉ ꢊꢋ ꢌꢍ ꢎ ꢏꢐ ꢑꢊꢍꢋ ꢊꢒ ꢓꢔ ꢎ ꢎ ꢕꢋꢑ ꢐꢒ ꢍꢌ ꢖꢔꢗ ꢘꢊꢓ ꢐꢑꢊ ꢍꢋ ꢙꢐ ꢑꢕꢚ ꢀꢎ ꢍꢙꢔ ꢓꢑꢒ
ꢓ ꢍꢋ ꢌꢍꢎ ꢏ ꢑꢍ ꢒ ꢖꢕ ꢓ ꢊ ꢌꢊ ꢓ ꢐ ꢑꢊ ꢍꢋꢒ ꢖ ꢕꢎ ꢑꢛꢕ ꢑꢕ ꢎ ꢏꢒ ꢍꢌ ꢆꢕꢜ ꢐꢒ ꢇꢋꢒ ꢑꢎ ꢔꢏ ꢕꢋꢑ ꢒ ꢒꢑ ꢐꢋꢙ ꢐꢎ ꢙ ꢝ ꢐꢎ ꢎ ꢐ ꢋꢑꢞꢚ
ꢀꢎ ꢍ ꢙꢔꢓ ꢑ ꢊꢍ ꢋ ꢖꢎ ꢍ ꢓ ꢕ ꢒ ꢒ ꢊꢋ ꢟ ꢙꢍ ꢕ ꢒ ꢋꢍꢑ ꢋꢕ ꢓꢕ ꢒꢒ ꢐꢎ ꢊꢘ ꢞ ꢊꢋꢓ ꢘꢔꢙ ꢕ ꢑꢕ ꢒꢑꢊ ꢋꢟ ꢍꢌ ꢐꢘ ꢘ ꢖꢐ ꢎ ꢐꢏ ꢕꢑꢕ ꢎ ꢒꢚ
Copyright 2003, Texas Instruments Incorporated
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
This integrated circuit can be damaged by ESD.
Texas Instruments recommends that all
integrated circuits be handled with appropriate
precautions. Failure to observe proper handling and
installation procedures can cause damage.
(1)
ABSOLUTE MAXIMUM RATINGS
Power Supply (+V )
S
+6V
Analog Input
−0.3V to (+V + 0.3V)
S
Logic Input
−0.3V to (+V + 0.3V)
S
ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small
parametric changes could cause the device not to meet its
published specifications.
Case Temperature
Junction Temperature
Storage Temperature
+100°C
+150°C
−40°C to +150°C
(1)
Stresses above those listed under “Absolute Maximum Ratings”
may cause permanent damage to the device. Exposure to
absolute maximum conditions for extended periods may affect
device reliability.
PACKAGE/ORDERING INFORMATION
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
DESIGNATOR
PACKAGE
MARKING
TRANSPORT MEDIA,
QUANTITY
PRODUCT
PACKAGE-LEAD
ORDERING NUMBER
(1)
VCA2619YT
VCA2619YR
Tape and Reel, 250
Tape and Reel, 2000
VCA2619Y
TQFP−32
PBS
−40°C to +85°C
VCA2619Y
(1)
For the most current specification and package information, refer to our web site at www.ti.com.
2
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
ELECTRICAL CHARACTERISTICS
At T = +25°C, V
= 5V, load resistance = 500Ω on each output to ground single−ended output (1Vpp), MGS = 111, VCA
= 2.9V and
A
DD
CNTL
f
IN
= 5MHz, unless otherwise noted.
VCA2619
TYP
MIN
MAX
PARAMETER
CONDITIONS
UNIT
BUFFER
Input Resistance
Input Capacitance
Input Bias Current
600
5
kΩ
pF
nA
1
Maximum Input Voltage
Input Voltage Noise
Input Current Noise
Noise Figure
1
Vpp
nV/√Hz
fA/√Hz
dB
PGA Gain = 45dB, R = 50Ω
Independent of Gain
5.9
350
13
S
R
= 550Ω, PGA Gain = 45dB, R = 75Ω
F
S
Bandwidth
100
MHz
PROGRAMMABLE VARIABLE GAIN AMPLIFIER
Peak Input Voltage
1
Vpp
MHz
V/µs
V
−3dB Bandwidth
20
Slew Rate
300
Output Signal Range
Output Impedance
R
≥ 500Ω Each Side to Ground
2.5 1
L
1
Ω
Output Short−Circuit Current
3rd-Harmonic Distortion
2nd-Harmonic Distortion
2nd-Harmonic Distortion
Overload Performance (2nd-Harmonic Distortion)
Time Delay
40
mA
dBc
dBc
dBc
dB
V
V
= 1Vpp, VCA
= 1Vpp, VCA
= 2.9V
= 2.9V
−45
−42
−60
−50
−50
OUT
OUT
CNTL
CNTL
Differential, V
OUT
= 2Vpp, VCA
= 3.0V, MGS = 011
= 2V
CNTL
Input Signal = 0.5Vpp, VCA
CNTL
−40 to −45
5
ns
IMD, 2−Tone
V
= 2Vpp, f = 9.95MHz
−59
−60
dBc
dB
OUT
2Vpp Differential
Crosstalk
ACCURACY
Gain Slope
VCA
VCA
VCA
= 0.4V to 2.9V
= 0.2V to 3.0V
= 0.4V to 2.9V
20
dB/V
dB
dB
mV
dB
dB
CNTL
CNTL
CNTL
(1)
Gain Error
2.75
1.50
50
52
50
2.0
Output Offset Voltage
Gain Range
VCA
VCA
= 0.2V to 3.0V
= 0.4V to 2.9V
CNTL
CNTL
48
GAIN CONTROL INTERFACE
Input Voltage (VCA
) Range
0 to 3.0
V
CNTL
Input Resistance
Response Time
1
MΩ
µs
45dB Gain Change
0.2
POWER SUPPLY
Specified Operating Range
Power Dissipation
Power−Down
4.75
5.0
240
9.2
5.25
300
V
mW
mW
(1)
Referenced to best fit dB−linear curve.
3
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
PIN CONFIGURATION
+INA
NC
1
2
3
4
5
6
7
8
24 VCACNTL
23 MGS3
22
21
VDDR
VBIAS
VCM
MGS2
MGS1
VCA2619
20 PD
19 NC
GNDR
NC
18
17
NC
+INB
DNC
PIN CONFIGURATION
PIN
DESIGNATOR
DESCRIPTION
PIN
DESIGNATOR
DNC
DESCRIPTION
Do Not Connect
1
+IN
NoninvertingInput Channel A
No Internal Connection
17
A
2
NC
18
19
20
23
22
23
24
25
26
27
28
29
30
31
32
NC
NC
PD
No Internal Connection
3
4
V
DDR
Internal Reference Supply
Bias Voltage
No Internal Connection
V
BIAS
Power-Down (Active LOW)
Maximum Gain Select 1 (MSB)
Maximum Gain Select 2
Maximum Gain Select 3 (LSB)
VCA Analog Control
5
V
CM
Common−Mode Voltage
Internal Reference Ground
No Internal Connection
Noninverting Input Channel B
No Internal Connection
No Internal Connection
Coupling Capacitor Channel B
Coupling Capacitor Channel B
+5V Supply Channel B
Ground Channel B
MGS
1
6
GND
MGS
2
R
7
NC
MGS
3
8
+IN
VCA
CNTL
B
9
NC
NC
N
OUTA
Negative VCA Output Channel A
Positive VCA Output Channel A
Ground Channel A
10
11
12
13
14
15
16
P
OUTA
C
C
GND
P2B
P1B
DDB
A
V
DDA
+5V Supply Channel A
V
C
Coupling Capacitor Channel A
Coupling Capacitor Channel A
No Internal Connection
P1A
P2A
GND
C
B
P
Positive Output Channel B
Negative Output Channel B
NC
NC
OUTB
N
OUTB
No Internal Connection
4
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
TYPICAL CHARACTERISTICS
At T = 25°C and V
otherwise noted.
= 5V, load resistance = 500Ω on each output to ground, differential output (2V ) MGS = 111, and f = 5MHz, unless
DD PP IN
A
GAIN vs VCA
GAIN ERROR vs TEMPERATURE
46
42
38
34
30
26
22
18
14
10
6
3.0
2.5
2.0
1.5
1.0
0.5
0
MGS = 111
MGS = 110
MGS = 101
_
+85 C
_
+25 C
MGS = 010
MGS = 011
MGS = 100
−
0.5
1.0
1.5
2.0
2.5
3.0
−
−
−
−
−
2
−
−
2
6
−
_
40 C
−
−
10
14
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
VCACNTL (V)
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9
VCACNTL (V)
GAIN ERROR vs VCACNTL
GAIN ERROR vs VCACNTL
3.0
2.5
2.0
1.5
1.0
0.5
0
3.0
2.5
2.0
1.5
1.0
0.5
0
MGS = 010
10MHz
1MHz
MGS = 100
−
−
−
−
−
−
0.5
1.0
1.5
2.0
2.5
3.0
−
−
−
−
−
−
0.5
1.0
1.5
2.0
2.5
3.0
5MHz
MGS = 111
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9
VCACNTL (V)
VCACNTL (V)
GAIN MATCH: CHA to CHB, VCACNTL = 0.4V
GAIN MATCH: CHA to CHB, VCACNTL = 2.9V
45
40
35
30
25
20
15
10
5
45
40
35
30
25
20
15
10
5
0
0
Delta Gain (dB)
Delta Gain (dB)
5
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
TYPICAL CHARACTERISTICS (continued)
At T = 25°C and V
otherwise noted.
= 5V, load resistance = 500Ω on each output to ground, differential output (2V ) MGS = 111, and f = 5MHz, unless
DD PP IN
A
GAIN vs FREQUENCY
(VCACNTL = 2.9V)
GAIN vs FREQUENCY
(MGS = 111)
50
45
40
35
30
25
20
15
10
5
50
40
30
20
10
0
VCACNTL = 2.9V
MGS = 111
MGS = 100
VCACNTL = 1.9V
VCACNTL = 0.9V
MGS = 010
−
−
10
20
0
100k
1M
10M
100M
100k
1M
10M
100M
Frequency (MHz)
Frequency (MHz)
INPUT REFERRED NOISE vs VCACNTL
RS= 50
OUTPUT REFERRED NOISE vs VCACNTL
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
1100
Ω
Ω
RS= 50
1000
900
800
700
600
500
400
300
200
100
0
MGS = 111
MGS = 111
MGS = 100
MGS = 100
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
VCACNTL (V)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
VCACNTL (V)
NOISE FIGURE vs RS
INPUT REFERRED NOISE vs RS
19
18
17
16
15
14
13
12
11
10
9
100
10
1
8
7
6
5
4
3
2
1
0
1
10
100
1k
10
100
1k
Ω
( )
RS
Ω
( )
RS
6
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
TYPICAL CHARACTERISTICS (continued)
At T = 25°C and V
otherwise noted.
= 5V, load resistance = 500Ω on each output to ground, differential output (2V ) MGS = 111, and f = 5MHz, unless
DD PP IN
A
NOISE FIGURE vs VCACNTL
HARMONIC DISTORTION vs FREQUENCY
(Differential, 2VPP, MGS = 010)
70
65
60
55
50
45
40
35
30
25
20
15
10
5
−
−
−
−
−
−
−
−
−
30
35
40
45
50
55
60
65
70
VCA
VCA
VCA
VCA
= 0.9V, H2
= 0.9V, H3
= 2.9V, H2
= 2.9V, H3
CNTL
CNTL
CNTL
CNTL
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
VCACNTL (V)
100k
1M
Frequency (Hz)
10M
10M
10M
HARMONIC DISTORTION vs FREQUENCY
(Differential, 2VPP, MGS = 100)
HARMONIC DISTORTION vs FREQUENCY
(Differential, 2VPP, MGS = 111)
−
−
−
−
−
−
−
−
−
−
−
−
−
30
35
40
45
50
55
60
65
70
75
80
85
90
−
−
−
−
−
−
−
−
−
−
−
30
35
40
45
50
55
60
65
70
75
80
VCA
VCA
VCA
VCA
= 0.9V, H2
= 0.9V, H3
= 2.9V, H2
= 2.9V, H3
C NTL
C NTL
C NTL
C NTL
VCA
VCA
VCA
VCA
= 0.9V, H2
= 0.9V, H3
= 2.9V, H2
= 2.9V, H3
CNTL
CNTL
CNTL
CNTL
100k
1M
10M
100k
1M
Frequency (Hz)
Frequency (Hz)
HARMONIC DISTORTION vs FREQUENCY
(Single−Ended, 1VPP, MGS = 010)
HARMONIC DISTORTION vs FREQUENCY
(Single−Ended, 1VPP, MGS = 100)
−
−
−
−
−
−
−
−
−
−
−
−
−
30
35
40
45
50
55
60
65
70
75
80
85
90
−
−
−
−
−
−
−
−
−
−
−
−
−
30
35
40
45
50
55
60
65
70
75
80
85
90
VCA
VCA
VCA
VCA
= 0.9V, H2
VCA
VCA
VCA
VCA
= 0.9V, H2
CNTL
CNTL
CNTL
CNTL
CNTL
= 0.9V, H3
= 0.9V, H3
= 2.9V, H2
= 2.9V, H3
CNTL
CNTL
CNTL
= 2.9V, H2
= 2.9V, H3
100k
1M
10M
100k
1M
Frequency (Hz)
Frequency (Hz)
7
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
TYPICAL CHARACTERISTICS (continued)
At T = 25°C and V
otherwise noted.
= 5V, load resistance = 500Ω on each output to ground, differential output (2V ) MGS = 111, and f = 5MHz, unless
DD PP IN
A
HARMONIC DISTORTION vs FREQUENCY
(Single−Ended, 1VPP, MGS = 111)
HARMONIC DISTORTION vs VCACNTL
(Differential, 2VPP, 5MHz)
−
−
−
−
−
−
−
−
−
−
−
−
−
30
35
40
45
50
55
60
65
70
75
80
85
90
0
5
−
MGS = 010, H2
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
MGS = 100, H2
MGS = 111, H2
MGS = 010, H3
MGS = 100, H3
MGS = 111, H3
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
VCA
VCA
VCA
VCA
= 0.9V, H2
CNTL
CNTL
CNTL
CNTL
= 0.9V, H3
= 2.9V, H2
= 2.9V, H3
0.9
1.1
1.3
1.5
1.7
1.9
2.1
2.3
2.5
2.7
2.9
100k
1M
10M
VCACNTL (V)
Frequency (Hz)
HARMONIC DISTORTION vs VCACNTL
(Single−Ended, 1VPP, 5MHz)
INTERMODULATION DISTORTION
(Single−Ended, 1VPP, fIN = 10MHz)
−
30
35
40
45
50
55
60
65
0
MGS = 010, H2
MGS = 100, H2
MGS = 111, H2
MGS = 010, H3
MGS = 100, H3
MGS = 111, H3
−
−
−
−
−
−
−
−
−
10
20
30
40
50
60
70
80
90
−
−
−
−
−
−
−
−
100
0.9
1.1
1.3
1.5
1.7
1.9
2.1
2.3
2.5
2.7
2.9
9.5 9.6 9.7 9.8 9.9 10.0 10.1 10.2 10.3 10.4 10.5
Frequency (MHz)
VCACNTL (V)
CROSS TALK vs FREQUENCY
(Differential, 2VPP, MGS = 011)
INTERMODULATION DISTORTION
(Differential, 2 VPP, fIN = 10MHz)
0
0
−
−
−
−
−
−
−
−
−
10
20
30
40
50
60
70
80
90
−
−
−
−
−
−
−
10
20
30
40
50
60
70
VCACNTL = 0.9V
VCACNTL = 1.9V
VCACNTL = 2.9V
10M
−
100
1M
20M
9.5 9.6 9.7 9.8 9.9 10.0 10.1 10.2 10.3 10.4 10.5
Frequency (MHz)
Frequency (Hz)
8
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
TYPICAL CHARACTERISTICS (continued)
At T = 25°C and V
otherwise noted.
= 5V, load resistance = 500Ω on each output to ground, differential output (2V ) MGS = 111, and f = 5MHz, unless
DD PP IN
A
ICC (CHA and CHB) vs TEMPERATURE
OVERLOAD DISTORTION vs FREQUENCY
55
54
53
52
51
50
49
48
47
46
45
0
10
20
30
40
50
60
0.2V
0.3V
0.5V
1V
−
−
−
−
−
−
−
−
−
−
40 30 20 10
0
10 20 30 40 50 60 70 80 90
1M
10M
_
Temperature ( C)
Frequency (Hz)
OVERVIEW
The VCA2619 is a dual-channel, VGA consisting of three
primary blocks: an Input Buffer, a VCA, and a PGA. All
stages are ac coupled, with the coupling into the PGA
stage being made variable by placing an external capaci-
tor between the CP1 and CP2 pins. This will be discussed
further in the PGA section. By using the internal coupling
into the PGA, the result is a high-pass filter characteristic
with cutoff at approximately 75kHz. The output PGA natu-
rally rolls off at around 30MHz, making the usable band-
width of the VCA2619 between 75kHz and 30MHz.
INPUT BUFFER
The input buffer is a unity gain amplifier (gain of +1) with
a bandwidth of 100MHz with an input resistance of approx-
imately 600kΩ. The input buffer isolates the circuit driving
the VCA2619 inputs from the internal VCA block, which
would present a varying impedance to the input circuitry.
To allow symmetrical operation of the input buffer, the input
to the buffer must be ac coupled through an external ca-
pacitor. The recommended value of the capacitor is
0.01µF. It should be noted that if the capacitor value were
increased, the power-on time of the VCA2619 would be in-
creased. If a decrease in the power-on time is needed, the
value can be decreased to no less than 100pF.
Channel A
Input
Channel A
Output
Buffer
VCA
PGA
Maximum
Gain
Select
Analog
Control
VCA
Control
MGS
Channel B
Input
Channel B
Output
Buffer
VCA
PGA
Figure 1. Simplified Block Diagram of the
VCA2619.
9
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
The MGS bits adjust the overall range of attenuation and
maximum gain while the VCACNTL voltage adjusts the
actual attenuation factor. Figure 3 is a simplified version of
the voltage control attenuator. Figure 4 illustrates the
piecewise approximation to the logarithmic control
characteristics. At any given maximum gain setting, the
analog variable gain characteristic is linear in dB as a
function of the control voltage, and is created as a
piecewise approximation of an ideal dB-linear transfer
function. The VCA control circuitry is common to both
channels of the VCA2619. The range for the VCACNTL
input spans from 0V to 3V. Although overdriving the
VCACNTL input above the recommended 3V maximum will
not damage the part, this condition should be avoided.
VOLTAGE-CONTROLLED ATTENUATOR
The magnitude of the VCA input signal from the input
buffer is reduced by a programmable attenuation factor,
set by the analog VCA Control Voltage (VCACNTL) at pin
24. The maximum attenuation is programmable by using
the three MGS bits (pins 21, 22, and 23). Figure 2
illustrates this dual-adjust characteristic.
0
Minimum Attenuation
−
41
Maximum Attenuation
−
52.3
0
3.0V
Control Voltage
Figure 2. Swept Attenuator Characteristic.
RS
Input
VCM
Output
Q1A
Q1B
Q2A
Q2B
Q3A
Q3B
Q4A
Q4B
Q5A
Q5B
A1
A2
A3
A4
A5
B1
B2
Figure 3. Simplified Attenuator Diagram.
10
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
Attenuator
Input
A1 to A10 Attenuator Stages
QS
Attenuator
Output
RS
Q
1
Q
2
Q
3
Q
4
Q
5
Q6
Q
7
Q
8
Q9
A10
Q
10
VCM
A1
A2
A3
A4
A5
A6
A7
A8
A9
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
Control
Input
C1 to C10 Clipping Amplifiers
0dB
5.2dB
−
Attenuation Characteristic of Individual FETs
VCM
V
T
−
0
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
Characteristic of Attenuator Control Stage Output
OVERALL CONTROL CHARACTERISTICS OF ATTENUATOR
0dB
52.3dB
−
0.2V
3V
Control Signal
Figure 4. Piecewise Approximation to Logarithmic Control Characteristics.
11
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
Table 1. MGS Settings.
PGA POST-AMPLIFIER
Figure 5 shows a simplified circuit diagram of the PGA
block. As stated before, the input to the PGA is ac coupled
with an internal capacitor. Provisions are made so that an
external capacitor can be placed in parallel with the inter-
nal capacitor, thus lowering the usable low-frequency
bandwidth. The low-frequency bandwidth is set by the fol-
lowing equation:
ATTENUATOR +
DIFFERENTIAL PGA
GAIN
MGS
SETTING
ATTENUATOR GAIN
VCA = 0.2V TO 3V
CNTL
Not Valid
000
001
010
011
100
101
110
111
Not Valid
Not Valid
Not Valid
−41.0dB to 0dB
−43.3dB to 0dB
−46.4dB to 0dB
−48.2dB to 0dB
−50.2dB to 0dB
−52.3dB to 0dB
−12dB to 29dB
−11.5dB to 31.8dB
−11.5dB to 34.9dB
−10.6dB to 37.6dB
−9.8dB to 40.4dB
−9.3dB to 43.3dB
1
(
(
))
2 @ p @ 500kW @ 220pF ) CEXTERNAL
(1)
where CEXTERNAL is the external capacitor value in farads.
The PGA architecture converts the single−ended signal
from the VCA into a differential signal. Low input noise was
also a requirement of the PGA design due to the large
amount of signal attenuation that can be asserted before
the PGA. At minimum VCA attenuation (used for small in-
put signals), the input buffer noise dominates; at maximum
VCA attenuation (large input signals), the PGA noise dom-
inates. Note that if the PGA output is single−ended, the ap-
parent gain will be 6dB lower.
Care should be taken to avoid using too large a value of
capacitor, as this can increase the power-on delay time.
The PGA gain is programmed with the same MGS bits that
control the VCA maximum attenuation factor. For VCA-
= 3V (no attenuation), the VCA + PGA gain will be
CNTL
controlled by the programmed PGA gain (29dB to 43dB in
approximately 3dB steps). For clarity, the gain and attenu-
ation factors are detailed in Table I.
VDD
To Bias
Circuitry
Q1
Q11
Q12
Q9
RL
RL
VCAOUT
P
VCAOUTN
Q3
Q4
Q8
VCM
VCM
RS1
RS2
Q13
Q7
+In
In
−
Q14
Q2
Q10
Q5
Q6
To Bias
Circuitry
Figure 5. Simplified Block Diagram of PGA.
12
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SBOS276A − AUGUST 2003 − REVISED AUGUST 2003
Adequate power−supply decoupling must be used in order
to achieve the best possible performance. Decoupling ca-
pacitors on the VCACNTL voltage should also be used to
help minimize noise. Recommended values can be ob-
tained from the layout diagram of Figure 6.
LAYOUT CONSIDERATIONS
The VCA2619 is an analog amplifier capable of high gain.
When working on a PCB layout for the VCA2619, it is rec-
ommended to utilize a solid ground plane that is connected
to analog ground. This helps to maximize the noise perfor-
mance of the VCA2619.
+5V
0.1µF
1µF
+5V
0.1µF
0.1µF
1µF
1µF
28
3
5
0.01µF
0.01µF
VDDA VDDR VCM
1
25
OUT
−
INA
INA
−OUTA
A
0.01µF
26
+OUTA
+OUTA
VCA2619
0.01µF
0.01µF
16
15
−OUTB
+OUTB
24
−OUTB
0.01µF
8
INB
INB
+OUTB
VDDB VBIAS VCNTL
13
4
1 F
µ
0.1 F
µ
0.1 F
µ
+5V
1 F
µ
0.1µF
VCACNTL
Figure 6. VCA2619 Layout.
13
PACKAGE OPTION ADDENDUM
www.ti.com
9-Dec-2004
PACKAGING INFORMATION
Orderable Device
Status (1)
Package Package
Pins Package Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
Qty
Type
TQFP
TQFP
Drawing
VCA2619YR
VCA2619YT
ACTIVE
ACTIVE
PBS
32
32
2000
250
None
None
Call TI
Call TI
Call TI
Call TI
PBS
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - May not be currently available - please check http://www.ti.com/productcontent for the latest availability information and additional
product content details.
None: Not yet available Lead (Pb-Free).
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Green (RoHS & no Sb/Br): TI defines "Green" to mean "Pb-Free" and in addition, uses package materials that do not contain halogens,
including bromine (Br) or antimony (Sb) above 0.1% of total product weight.
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDECindustry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
MECHANICAL DATA
MPQF027 – NOVEMBER 1995
PBS (S-PQFP-G32)
PLASTIC QUAD FLATPACK
0,23
0,17
M
0,50
0,08
24
17
25
32
16
9
0,13 NOM
1
8
3,50 TYP
Gage Plane
5,05
SQ
4,95
0,25
7,10
SQ
0,10 MIN
6,90
0°–7°
0,70
0,40
1,05
0,95
Seating Plane
0,08
1,20 MAX
4087735/A 11/95
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
1
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