Texas Instruments (TI) has introduced what it claims is the most efficient envelope tracking power supply solution to support 3G and 4G LTE multi-mode, multi-band RF power amplifiers used in smartphones and tablets.
The LM3290 step-down converter with integrated DC boost and companion LM3291 linear amplifier has been designed to enable the use of envelope tracking techniques in RF transmitters to reduce the power amplifier temperature by 20 degrees C and reduce overall power consumption by 25 percent, compared to systems that use average power tracking.
LTE signals, available in more than 20 distinct bands across the world from various carriers, provide high-speed data transmission that need a high peak-to-average ratio (PAR), and generate higher transmit power, which reduces the efficiency of RF power amplifiers and creates extra heat. The LM3290 and LM3291, which support battery voltages down to 2.5 V, provide high efficiency at higher power output levels and high PAR, while meeting stringent receive band noise requirements in all LTE bands.
Key features and benefits of LM3290 and LM3291 include: bandwidth and battery voltage flexibility; envelope tracking capability helps reduce heat and power consumption by as much as 25 percent and achieves greater than 90-percent efficiency using advanced power tracking for LTE 25RB; increased power capacity; supports the MIPI eTrak analogue differential front end interface for envelope tracking and a 1.8-V MIPI RFFE digital interface to simplify integration with the industry’s newest RF platforms. The devices also allow seamless transition between envelope tracking and average power tracking operating modes.
The LM3290 and LM3291 provide high efficiency, low noise, low output impedance and low output ripple voltage at high LTE bandwidths (LTE10 and 20). The devices support a minimum bandwidth of 75 MHz – belived to be an industry-first when using envelope tracking – providing high accuracy with adjacent channel leakage ratio and noise performance.