1FEATURES

23• 3V OPERATION

• LOW INPUT NOISE:

– 1.05nV/√Hz at f IN = 5MHz

• EXTREMELY LOW POWER OPERATION:

– 103mW/CHANNEL

• INTEGRATED LOW-PASS, ANTI-ALIASING

BUTTERWORTH FILTER

– 14.5MHz BANDWIDTH

• INTEGRATED INPUT CLAMP DIODES

• DIFFERENTIAL OUTPUT

• INTEGRATED INPUT LNA

• READABLE CONTROL REGISTERS

• 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 low-pass filter.