VCA8617 Datasheet, PDF (1/26 Pages) Burr-Brown (TI) – 8-Channel VARIABLE GAIN AMPLIFIER

VCA8617
SBOS308B − AUGUST 2004 − REVISED NOVEMBER 2004
8-Channel
VARIABLE GAIN AMPLIFIER
FEATURES
D 3V OPERATION
D LOW INPUT NOISE: 1.0nV//Hz at f_IN = 5MHz
D EXTREMELY LOW POWER OPERATION:
100mW/CHANNEL
D INTEGRATED LOW-PASS, 2-POLE FILTER
15MHz BANDWIDTH
D INTEGRATED INPUT CLAMP DIODES
D DIFFERENTIAL OUTPUT
D INTEGRATED INPUT LNA
D READABLE CONTROL REGISTERS
D INTEGRATED CONTINUOUS WAVE (CW)
PROCESSOR
DESCRIPTION
The VCA8617 is an 8-channel variable gain amplifier
ideally suited to portable ultrasound applications.
Excellent dynamic performance enables use in
low-power, high-performance portable applications.
Each channel consists of a 20dB gain Low-Noise
pre-Amplifier (LNA) and a Variable Gain Amplifier
(VGA). The differential outputs of the LNA can be
switched through the 8x10 cross-point switch, which is
programmable through the serial interface input port.
The output of the LNA is fed directly into the VGA stage.
The VGA consists of two parts, a Voltage-Controlled
Attenuator (VCA) and a Programmable Gain Amplifier
(PGA). The gain and gain range of the PGA can be
digitally configured separately. The gain of the PGA can
vary between four discrete settings of 25dB, 30dB,
35dB, and 40dB. The VCA has four programmable
maximum attenuation settings: 29dB, 33dB, 36.5dB,
and 40dB. Also, the VCA can be continuously varied by
a control voltage from 0dB to a maximum of 29dB,
33dB, 36.5dB, and 40dB.
The output of the PGA feeds directly into an integrated
two-pole, low-pass filter.
DATA
CLK
CS
D(0−3)
Serial
Interface
LNAIN1
10x8
FIFO
LNA
•••
+
1 _{•••}
−
CW Processor
CW(0−9)
Analog
Control
Attenuator
PGA
2−Pole
Filter
OutP⁽¹⁾
OutN⁽¹⁾
LNAIN8
V_LNA
LNA
V_LNA
•••
+
8
−
Attenuator
Analog
Control
PGA
2−Pole
Filter
OutP⁽⁸⁾
OutN⁽⁸⁾
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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.
Copyright  2004, Texas Instruments Incorporated
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