VHF-to-Microwave, +3V,

General-Purpose Amplifiers

_______________________________________________________________________________________

7

_______________Detailed Description

The MAX2630–MAX2633 are broadband amplifiers with

3dB bandwidth greater than 1GHz. Their small size and

internal bias circuitry make them ideal for applications

where board space is limited. The MAX2632/MAX2633

have a user-selectable bias current that allows the user

to set both gain and output power for a particular appli-

cation, and the MAX2631/MAX2633 incorporate shut-

down capability.

__________Applications Information

External Components

The MAX2630–MAX2633 are easy to use, as shown in the

Typical Operating Circuit and Figures 1, 2 and 3. Input

and output series capacitors may be necessary to block

DC bias voltages generated by the amplifiers from inter-

acting with adjacent circuitry. These capacitors must be

large enough to contribute negligible reactance in a 50

Ω

system at the minimum operating frequency. Use the fol-

lowing equation to calculate their minimum value:

where f (in megahertz) is the minimum operating

frequency.

tion. To accomplish this, connect a capacitor between

practical. Use the same equation given above (for DC-

blocking capacitor values) to calculate the minimum

additional bypassing may be necessary. This can be

done farther away from the package, if needed.

Proper grounding of the GND pin is essential. If the PC

board uses a topside RF ground, connect it directly to

the GND pin. For a board where the ground plane is not

on the component side, the best technique is to con-

nect the GND pin to it with a plated through-hole close

to the package.

An on-chip buffer at the MAX2631/MAX2633’s SHDN

pin makes bypassing this pin unnecessary except in

very noisy applications. When RF filtering is needed,

Since negligible current flows into this pin, additional

RF filtering may be done with a series resistor.

To set the MAX2632/MAX2633’s supply current,

connect a resistor from the BIAS pin to ground. To

estimate the value of this resistor, refer to the graph

Characteristics.

C

f

pF

BLOCK

,

()

=

53 000

BIAS

GND

OUT

IN

IN

OUT

BIAS

MAX2632

Figure 3. MAX2632 Typical Operating Circuit

OUT

OUT

IN

GND

IN

MAX2630

OFF

ON

SHDN

GND

OUT

IN

IN

OUT

BIAS

MAX2631

Figure 1. MAX2630 Typical Operating Circuit

Figure 2. MAX2631 Typical Operating Circuit