Detailed Description

The MAX2034 is a four-channel, ultra-low-noise pream-

plifier. Each amplifier features single-ended inputs, dif-

ferential outputs, and provides an accurate fixed gain of

19dB with a wide -3dB bandwidth of 70MHz. The high-

gain accuracy of the amplifier allows for exceptional

channel-to-channel gain matching, which is necessary

for high-performance ultrasound-imaging applications.

The device has an exceptionally low noise figure, making

it ideal for use in ultrasound front-end designs. Noise fig-

ure is typically 2.2dB for a source impedance and pro-

grammed input impedance of 200Ω.

The MAX2034 is optimized for excellent dynamic range

and linearity performance characteristics, making it ideal

for ultrasound-imaging modalities including second har-

monic 2D imaging and continuous wave Doppler. The

5MHz. See the Ultrasound-Specific IMD3 Specification in

the Applications Information section.

Active Impedance Matching

To provide exceptional noise-figure characteristics, the

input impedance of each amplifier uses a feedback

topology for active impedance matching. A feedback

the inverting output of the amplifier to the input. The

by 1 + (A / 2). The factor of two is due to the gain of the

amplifier, A, being defined with a differential output. For

common input impedances, the internal digitally pro-

grammed impedances can be used (see Table 1). For

other input impedances, program the impedance for

external resistor operation, and then use an externally

supplied resistor to set the input impedance according

to the above formula.

The gain and input impedance of the MAX2034 vs. fre-

quency are shown in the Typical Operating Char-

acteristics. Both gain and input impedance are well

behaved, with no peaking characteristics. This allows

the device to be used with a variety of input networks,

with no requirement for series ferrite beads or shunt

capacitors for stability control.

Quad-Channel, Ultra-Low-Noise Amplifier with

Digitally Programmable Input Impedance

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7

Pin Description (continued)

PIN

NAME

FUNCTION

18, 19, 42

D1, D0, D2

Digitally Programmable Inputs. Programs the input impedance of each amplifier. See Table 1 on

input impedance programming information.

23

OUT4-

Channel 4 LNA Analog Inverting Output

24

OUT4+

Channel 4 LNA Analog Noninverting Output

28

OUT3-

Channel 3 LNA Analog Inverting Output

29

OUT3+

Channel 3 LNA Analog Noninverting Output

31

OUT2-

Channel 2 LNA Analog Inverting Output

32

OUT2+

Channel 2 LNA Analog Noninverting Output

35

OUT1-

Channel 1 LNA Analog Inverting Output

36

OUT1+

Channel 1 LNA Analog Noninverting Output

43

PD

Power-Down. Drive PD high to put the device in sleep mode. Drive PD low for normal mode.

47

ZF1

Channel 1 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.

48

IN1

Channel 1 LNA Analog Input. Single-ended input for channel 1 amplifier. Connect the analog input to

the source circuit through a series capacitor.

EP

GND

Exposed Paddle. Solder the exposed paddle to the ground plane using multiple vias.

D2

D1

D0

Ω)

000

50

001

100

010

200

011

1k

100

101

110

111

Defined by external resistor

Table 1. Digitally Programmable Input

Impedance