VCA824
VC
A8
24
VC
A824
www.ti.com....................................................................................................................................... SBOS394C – NOVEMBER 2007 – REVISED DECEMBER 2008
Ultra-Wideband, > 40dB Gain Adjust Range, Linear in V/V
VARIABLE GAIN AMPLIFIER
FEATURES
1
DESCRIPTION
• 710MHz SMALL-SIGNAL BANDWIDTH
(G = +2V/V)
• 320MHz, 4VPP BANDWIDTH (G = +10V/V)
• 0.1dB GAIN FLATNESS to 135MHz
• 2500V/µs SLEW RATE
• > 40dB GAIN ADJUST RANGE
• HIGH GAIN ACCURACY: 20dB ±0.3dB
• HIGH OUTPUT CURRENT: ±90mA
23
The VCA824 is a dc-coupled, wideband, linear in V/V,
continuously
variable,
voltage-controlled
gain
amplifier. It provides a differential input to
single-ended conversion with a high-impedance gain
control input used to vary the gain down 40dB from
the nominal maximum gain set by the gain resistor
(RG) and feedback resistor (RF).
APPLICATIONS
•
•
•
•
•
DIFFERENTIAL LINE RECEIVERS
DIFFERENTIAL EQUALIZERS
PULSE AMPLITUDE COMPENSATION
VARIABLE ATTENUATORS
VOLTAGE-TUNABLE ACTIVE FILTERS
VIN1
RF
+VIN
RG+
RS
R1
RL
FB
RG
VOUT
VCA824
C1
CL
RG-
VIN2
-VIN
20W
The VCA824 internal architecture consists of two
input buffers and an output current feedback amplifier
stage integrated with a multiplier core to provide a
complete variable gain amplifier (VGA) system that
does not require external buffering. The maximum
gain is set externally with two resistors, providing
flexibility in designs. The maximum gain is intended
to be set between +2V/V and +40V/V. Operating from
±5V supplies, the gain control voltage for the VCA824
adjusts the gain linearly in V/V as the control voltage
varies from +1V to –1V. For example, set for a
maximum gain of +10V/V, the VCA824 provides
10V/V, at +1V input, to 0.1V/V at –1V input of gain
control range. The VCA824 offers excellent gain
linearity. For a 20dB maximum gain, and a
gain-control input voltage varying between 0V and
1V, the gain does not deviate by more than ±0.3dB
(maximum at +25°C).
RS
VCA824 RELATED PRODUCTS
DUALS
GAIN
ADJUST
RANGE
(dB)
Differential Equalizer
SINGLES
9
INPUT
NOISE
(nV/√Hz)
SIGNAL
BANDWIDTH
(MHz)
VCA810
—
80
2.4
35
3
—
VCA2612
45
1.25
80
0
—
VCA2613
45
1
80
—
VCA2615
52
0.8
50
—
VCA2617
48
4.1
50
VCA820
—
40
8.2
150
-15
VCA821
—
40
6.0
420
-18
VCA822
—
40
8.2
150
VCA824
—
40
6.0
420
Equalized Frequency Response
Gain (dB)
6
Initial Frequency Response
of the VCA824 with RC Load
-3
-6
-9
-12
-21
-24
1M
10M
100M
1G
Frequency (Hz)
Differential Equalization of an RC Load
1
2
3
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Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
X2Y is a registered trademark of X2Y Attenuators LLC.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007–2008, Texas Instruments Incorporated