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MAX2411AEEI

Low-Cost RF Up/Downconverter with LNA and PA Driver

Maxim Integrated 

Low-Cost RF Up/Downconverter

with LNA and PA Driver

_________________________________________________Pin Description (continued)

PIN

NAME

FUNCTION

RF Input to Receive Mixer (downconverter). This input typically requires a matching network for

24

RXMXIN connecting to an external filter. AC couple to this pin. See the Typical Operating Characteristics

for a plot of RXMXIN Impedance vs. Frequency.

25

GND

Receive Mixer Input Ground. Connect GND to the PC board ground plane with minimal inductance.

26

GND

LNA Output Ground. Connect GND to the PC board ground plane with minimal inductance.

LNA Output. AC couple to this pin. This output typically provides a VSWR of better than 2:1 at fre-

27

LNAOUT

quencies from 1.7GHz to 3GHz with no external matching components. At other frequencies, a

matching network may be required to match LNAOUT to an external filter. Consult the Typical

Operating Characteristics for a plot of LNA Output Impedance vs. Frequency.

_______________Detailed Description

The MAX2411A consists of five major components: a

transmit mixer followed by a variable-gain power-

amplifier (PA) driver as well as a low-noise amplifier

(LNA), receive mixer, and power-management section.

The following sections describe each of the blocks in

the MAX2411A Functional Diagram.

Low-Noise Amplifier (LNA)

The LNA is a wideband, single-ended cascode amplifi-

er that can be used over a wide range of frequencies.

Refer to the LNA Gain vs. Frequency graph in the

Typical Operating Characteristics. Its port impedances

are optimized for operation around 1.9GHz, requiring

only a 1pF shunt capacitor at the LNA input for a VSWR

of better than 2:1 and a noise figure of 2.4dB. As with

every LNA, the input match can be traded off for better

noise figure.

PA Driver

The PA driver has typically 15dB of gain, which is

adjustable over a 35dB range via the GC pin. At full gain,

the PA driver has a noise figure of 3.5dB at 1.9GHz.

For input and output matching information, refer to the

Typical Operating Characteristics for plots of PA Driver

Input and Output Impedance vs. Frequency.

Bidirectional IF Port

The MAX2411A has a unique bidirectional differential IF

port, which can eliminate the need for separate transmit

and receive IF filters, reducing cost and component count.

Consult the Typical Operating Circuit for more information.

For single-ended operation, connect the unused IF port to

VCC and bypass with a 1000pF capacitor to GND.

In receive mode, the IF and IF pins are open-collector

outputs that need external inductive pull-ups to VCC for

proper operation. These inductors are typically used as

part of an IF matching network.

In transmit mode, IF and IF are high-impedance inputs

that are internally AC coupled to the transmit mixer.

This internal AC coupling prevents the DC bias voltage

required for the receive mixer outputs from reaching

the transmit mixer inputs.

Receive Mixer

The receive mixer is a wideband, double-balanced

design with excellent noise figure and linearity. Inputs to

the mixer are the RF signal at the RXMXIN pin and the

LO inputs at LO and LO. The downconverted output sig-

nal appears at the IF port. For more information, see the

Bidirectional IF Port section. The conversion gain of the

receive mixer is typically 9.4dB with a 9.2dB noise figure.

RF Input

The RXMXIN input is typically connected to the LNA out-

put through an off-chip filter. This input is externally

matched to 50Ω. See the Typical Operating Circuit for an

example matching network and the Receive Mixer Input

Impedance vs. Frequency graph in the Typical Operating

Characteristics.

Local-Oscillator Inputs

The LO and LO pins are internally terminated with 50Ω

on-chip resistors. AC couple the local-oscillator signal

to these pins. If a single-ended LO source is used, con-

nect LO directly to ground.

Transmit Mixer

The transmit mixer takes an IF signal at the IF port and

upconverts it to an RF frequency at the TXMXOUT pin.

For more information on the IF port, see the Bidirectional

IF Port section. The conversion gain is typically 8.5dB,

and the output 1dB compression point is typically

11.1dBm at 1.9GHz.

_______________________________________________________________________________________ 9

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