1FEATURES

23• Highly Programmable High-Current Linear

Amplifier

• > 75 MHz Typical Small Signal Bandwidth

• Extremely Low Output Impedance

• High Linearity

• Differential Analog Input Compatible with

eTrak 1.0 Standard

• Low Output Noise

• When paired with the LM3290 provides a

complete Envelope Modulator solution for

3G/4G Envelope Tracking Power Amplifiers.

• Automatically controlled through LM3290 in an

envelope modulation solution using MIPI®

RFFE 1.1-compatible interface.

APPLICATIONS

• 3G/LTE Handsets

• 3G//LTE Tablets

• 3G/LTE Data Cards and Wireless Modems

DESCRIPTION

The LM3291 is a high-speed linear amplifier that, with

its companion IC LM3290, constitutes an RF

Envelope Modulator (EM) for supplying 3G/4G Power

Amplifiers (PA) in envelope tracking systems. The

amplifier provides extremely low output impedance

and low output noise over a wide bandwidth.

In conjunction with an Envelope Tracking (ET)

capable RFIC and PA, the LM3291 and LM3290

greatly improve PA efficiency for 3G and LTE operation.

In ET mode, the LM3291 and LM3290 provide

envelope tracking supply voltage for the PA maximizing total EM + PA efficiency. The envelope

modulator follows the differential envelope reference

input signal delivered by the RFIC to the LM3291.

The output is a single-ended dynamic power supply

voltage to the PA.

The LM3291 supports 3G and LTE operation up to 20

MHz signal bandwidth.

The LM3291’s programmable parameters are

controlled by LM3290 via a direct serial interface

between the two devices. No additional controls are

needed in the system. This interface provides flexible

control and adjustment options to optimize LM3291

efficiency and noise performance for various

frequency bands and power levels.

At high TX output power, the EM can be operated in

ET mode where LM3290 and LM3291 together

modulate the supply of the PA with the envelope

signal to improve overall system efficiency. At low TX

output power, the EM can be transitioned to Average

Power Tracking (APT) mode where LM3291 is placed

into shutdown mode to improve system efficiency.

The LM3291 is available in a 12-pin lead-free DSBGA

package.

For the full datasheet, samples, or the EVM

hardware and software please contact a TI

representative at ET@list.ti.com.