TLW11755

April 1995

LMX2240

Intermediate Frequency Receiver

General Description

The LMX2240 is a monolithic integrated intermediate fre-

quency receiver suitable for use in Digital European Cord-

less Telecommunications (DECT) systems as well as other

mobile telephony and wireless communications applica-

The LMX2240 consists of a high gain limiting amplifier a

frequency discriminator and a received signal strength indi-

cator (RSSI) The high gain limiting amplifier and discrimina-

tor operate in the 40 MHz to 150 MHz frequency range and

the limiter has approximately 70 dB of gain The use of the

limiter and the discriminator provides a low cost high per-

formance demodulator for communications systems The

RSSI output can be used for channel quality monitoring

The LMX2240 is intended to support single conversion re-

ceivers This device saves power size and cost by eliminat-

ing the second local oscillator (LO) second converter (mix-

er) and additional filters The LMX2240 is recommended for

systems with channel bandwidths of 300 kHz to 25 MHz

The LMX2240 is available in a 16-pin JEDEC surface mount

plastic package

Features

Y

Typical operation at 110 MHz

Y

b

82 dBm

Y

High gain (70 dB) limiting amplifier

Y

Average current consumption 480 mA for DECT

handset (burst mode)

Y

a

3V operation

Y

Power down mode for increased current savings

Y

Part of a complete receiver solution with the LMX2216

LNAMixer the LMX231520 Phase-locked Loop and

the LMX2411 Baseband Processor

Y

Applications

Y

Digital European Cordless Telecommunications (DECT)

Y

Portable wireless communications (PCSPCN cordless)

Y

Wireless local area networks (WLANs)

Y

Digital cellular telephone systems

Y

Other wireless communications systems

Functional Block Diagram

TLW11755 – 1

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A