400MHz to 2500MHz SiGe

Ultra-Low-Noise Amplifiers

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Detailed Description

The MAX2640 and MAX2641 are ultra-low-noise ampli-

fiers that operate with RF input frequency ranges of

400MHz to 1500MHz (MAX2640) or 1400MHz to

2500MHz (MAX2641). These devices are available in

SOT23-6 packages and contain internal bias circuitry to

minimize the number of required external components.

Their small size and low external component count

make them ideal for applications where board space is

limited.

Applications Information

External Matching Components

The MAX2640/MAX2641 are easy to use, generally

requiring only five external components as shown in the

Typical Operating Circuit. To reduce external compo-

nent count further, replace external inductors with

microstrip transmission lines. The high reverse isolation

allows the tuning of the input matching network without

affecting the output match, and vice versa. Select input

and output matching networks to obtain the desired

combination of gain, noise figure, and return loss per-

formance. The

Typical Operating Circuits show the rec-

ommended input and output matching networks for

the MAX2640/MAX2641 at 900MHz and 1900MHz,

respectively. These values are optimized for best

simultaneous gain, noise figure, and return loss perfor-

mance. To aid in the design of matching networks for

other frequencies, Tables 1 and 2 list typical device S-

parameters and Tables 3 and 4 list typical device noise

parameters.

NAME

FUNCTION

1

RFIN

Amplifier Input. AC-couple to this pin with a DC blocking capacitor. Use recommended input matching

network (see

Typical Operating Circuit).

2, 3, 5

GND

Ground. For optimum performance, provide a low inductance connection to the ground plane.

PIN

4

RFOUT

Amplifier Output. Use the recommended series blocking or matching capacitor (see

Typical Operating

Circuit).

6

Supply Voltage. Bypass to ground directly at the supply pin. The value of the bypass capacitor is deter-

Typical Operating Circuit).

Pin Description