MAXREFDES39#: Power Amplifier Biasing with MAX11300 PIXI

Overview

The MAXREFDES39# power amplifier (PA) bias reference design uses the MAX11300 to bias and monitor PAs in RF base station system applications. Infineon's PTMA210152M-20W is used in this example, but any other power amplifier can be used. The MAX11300 provides a highly integrated solution for RF power amplifier bias infrastructure. The design uses all MAX11300 analog peripherals, requiring only one MAX11300 to bias and monitor the 2-stage RF power amplifier. Features of the reference design are as follows:

• Frequency Division Duplex (FDD) and Time Division Duplex (TDD) radio frequency (RF) power amplifier monitoring, bias configuration and control.

• Monitoring function

• Highly accurate measurement of voltage and current

• Measure current with Maxim's current-sense amplifier ( MAX44285 )

• Drain voltage and current of primary and secondary amplifiers

• Two external and one internal temperature monitors

• Gate Bias for Primary and Secondary Amplifiers

• control function

• RF PA quick on/off

• Synchronous TDD functionality

• High Efficiency, Adjustable Drain Voltage Power Supply

• LED signals and alarms

• Automatic control function


Figure 1. MAXREFDES39# system block diagram

The USB interface to the microcontroller and the serial port to the MAX11300 are isolated from the main circuit through the MAX14850 . The microcontroller part is powered via USB, while other circuit parts are powered by an independent 36V DC power supply. Figure 1 also includes the power supply control and monitoring of the RF PA.