OUT1

OUT1

IN1

LNA

V

LNA

V

LNA

VCA

Analog

Control

PGA

2-Pole

Filter

CW(0-9)

D

OUT

CWProcessor

(8x10)

5x8

FIFO

OUT8

IN8

LNA

VCA

PGA

2-Pole

Filter

·

·

·

·

·

·

D

IN

CLK

CS

Serial

Interface

PG

ATN

V

CNTRL

VCA8617

10

OUT8

VCA8617

www.ti.com

SBOS308F – AUGUST 2004 – REVISED NOVEMBER 2009

8-Channel VARIABLE GAIN AMPLIFIER

Check for Samples: VCA8617

1

FEATURES

DESCRIPTION

23

•

3V OPERATION

The VCA8617 is an 8-channel variable gain amplifier

ideally suited to portable ultrasound applications.

•

LOW INPUT NOISE:

Excellent

dynamic

performance

enables

use

in

–

1.05nV/

low-power, high-performance portable applications.

•

EXTREMELY LOW POWER OPERATION:

Each channel consists of a 20dB gain Low-Noise

–

103mW/CHANNEL

pre-Amplifier (LNA) and a Variable Gain Amplifier

(VGA). The differential outputs of the LNA can be

•

INTEGRATED LOW-PASS, ANTI-ALIASING

switched through the 8x10 cross-point switch, which

BUTTERWORTH FILTER

is programmable through the serial interface input

–

14.5MHz BANDWIDTH

port.

•

INTEGRATED INPUT CLAMP DIODES

The output of the LNA is fed directly into the VGA

•

DIFFERENTIAL OUTPUT

stage.

The

VGA

consists

of

two

parts,

a

Voltage-Controlled

Attenuator

(VCA)

and

a

•

INTEGRATED INPUT LNA

Programmable Gain Amplifier (PGA). The gain and

•

READABLE CONTROL REGISTERS

gain range of the PGA can be digitally configured

•

INTEGRATED CONTINUOUS WAVE (CW)

separately. The gain of the PGA can vary between

PROCESSOR

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 low-pass filter.

1

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.

2

SPI is a trademark of Motorola, Inc.

3

All other trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2004–2009, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.