VCA2612_14 Datasheet, PDF (1/25 Pages) Texas Instruments – Dual, VARIABLE GAIN AMPLIFIER with Low Noise Preamp

VCA2612
VCA2612
SBOS117C – SEPTEMBER 2000 – REVISED APRIL 2004
Dual, VARIABLE GAIN AMPLIFIER
with Low Noise Preamp
FEATURES
q LOW NOISE PREAMP:
• Low Input Noise: 1.25nV/√Hz
• Active Termination Noise Reduction
• Switchable Termination Value
• 80MHz Bandwidth
• 5dB to 25dB Gain Range
• Differential Input /Output
q LOW NOISE VARIABLE GAIN AMPLIFIER:
• Low Noise VCA: 3.3nV/√Hz, Differential
Programming Optimizes Noise Figure
• 24dB to 45dB Gain
• 40MHz Bandwidth
• Differential Input /Output
q LOW CROSSTALK: 52dB at Max Gain, 5MHz
q HIGH-SPEED VARIABLE GAIN ADJUST
q SWITCHABLE EXTERNAL PROCESSING
APPLICATIONS
q ULTRASOUND SYSTEMS
q WIRELESS RECEIVERS
q TEST EQUIPMENT
DESCRIPTION
The VCA2612 is a highly integrated, dual receive channel,
signal processing subsystem. Each channel of the product
consists of a low noise preamplifier (LNP) and a Variable
Gain Amplifier (VGA). The LNP circuit provides the neces-
sary connections to implement Active Termination (AT), a
method of cable termination which results in up to 4.6dB
noise figure improvement. Different cable termination char-
acteristics can be accommodated by utilizing the VCA2612’s
switchable LNA feedback pins. The LNP has the ability to
accept both differential and single-ended inputs, and gener-
ates a differential output signal. The LNP provides strappable
gains of 5dB, 17dB, 22dB, and 25dB.
The output of the LNP can be accessed externally for further
signal processing, or fed directly into the VGA. The VCA2612’s
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 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.
The VCA2612 also features low crosstalk and outstanding
distortion performance. The combination of low noise and gain
range programmability make the VCA2612 a versatile building
block in a number of applications where noise performance is
critical. The VCA2612 is available in a TQFP-48 package.
FBSW_CNTL
LNP_OUTN VCA_INN
VCA_CNTL
RF_{2 SWFB}
RF_{1 FB}
C_F
Input CC _LNPINP
VCA2612
(1 of 2 Channels)
Analog
Control
LNP_GS1
LNP LNP_GS2
Gain Set
LNP_GS3
LNP_INN
Low Noise
Preamp
5dB to 25dB
Voltage
Controlled
Attenuator
Maximum Gain Select
MGS₁ MGS₂ MGS₃
Maximum Gain
Select
Programmable
Gain Amplifier
24 to 45dB
VCA_OUTN
VCA_OUTP
LNP_OUTP VCA_INP
SEL
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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