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.