LMV248

Dual Band GSM Power Controller

General Description

The LMV248 RF power amplifier controller allows simple

implementation of transmit power control loops in GSM and

DCS/PCS and mobile phones. The LMV248 supports, GaAs

HBT and bipolar RF power amplifiers. The device operates

from a single supply of 2.5V to 5V. The LMV248 includes an

error amplifier with an input summing network, input and

output band switches, input filters, and output drivers. Ana-

log input signals processed are:

–

Coupler/detector voltages from GSM and PCN band

power amplifier outputs.

–

Base band DAC ramp signal.

–

Temperature compensation diode voltages.

–

Pre-bias voltage for faster PA control.

Selection of the GSM or PCN output driver is made using the

GSM/PCN band select pin.

The On/OFF pin allows rapid power up or shutdown of the

device during Tx or Rx slots. In the off mode, both output

drivers are set low for PA shutdown. In the on mode, the

non-active driver will remain low for continued PA shutdown.

A single external capacitor/resistor combination is used to

adjust the closed loop frequency response.

The LMV248 replaces multiple discrete parts, reducing

board area and cost. The LLP leadless package minimizes

board footprint and permits flexible optimized PCB place-

ment.

Features

n

Multi-band cellular operation (example: GSM, PCN)

n

Support of GaAs HBT and bipolar technology

n

Shutdown mode for power save in Rx slot (0.15µA)

n

Integrated ramp filter

n

Built-in current source for biasing Schottky diodes

n

Pre-biasing of PA control gate voltage (V

n

GPRS compliant

n

External loop compensation

n

Detector diode temperature compensation

n

Miniature packaging: LLP-16: 4mm x 4mm x 0.8mm

Applications

n

GSM mobile phone

n

TDMA RF control

n

Wireless LAN

n

PC and PDA modules

n

GPS navigation modules

Connection Diagram

16-Pin LLP

10137201

Top View

Typical Application Circuit

10137202

FIGURE 1.

September 2001

© 2001 National Semiconductor Corporation

DS101372

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