Efficiently Controlling Power Switching of GaN Power Amplifiers Using Power Management Modules

[Introduction]It is well known that powering up and powering down GaN PAs can be challenging in some designs because of the specific bias timing required for GaN PAs. Improper handling may result in component damage. Managing timing steps is critical. The good news is that the difficulty of this task has been reduced.

Our video will show how customers using GaN PAs can use the Qorvo ACT41000 power management module to efficiently control the power switching of these devices. This helps achieve the performance customers expect and simplifies the GaN biasing process.

Once the PA is set up through the ACT41000’s GUI, it automatically adjusts the power-up and power-down timing of the GaN PA and optimizes the PA static bias for excellent system performance (see Figure 1). This simplifies RF PA system design, making it more cost-effective and easier to use. Thanks to its auto-tuning capability, the ACT41000 eliminates the need for external digital-to-analog converters (DACs) and current sense amplifiers. As a result, not only is the system design simplified and the size of the system reduced, the number of components is reduced, and the overall bill of materials cost is reduced.

Figure 1: Block diagram of the ACT41000 design powering the QPA2211.

The ACT41000 is equipped with an evaluation platform and GUI to assist in fine-tuning the bias, as shown in Figure 2. The auto-tuning feature helps optimize the bias performance of the GaN PA during device aging or temperature changes. When the GaN PA detects environmental or aging changes, the ACT41000 fine-tunes the device’s voltage and current values ​​to adjust the optimal performance settings specified in the GUI. This is very important for applications such as 5G base stations (high temperature during the day and lower temperature at night). Autotune bias can be used to help optimize performance under these fluctuating conditions. With this capability, engineers can provide automated designs, making it easier to provide their users with more reliable optimized solutions.

Figure 2: GUI for setting up the ACT41000.

The ACT41000 operates from an input voltage of 4.5 to 40 V; at 4 A, it generates a regulated and adjustable output voltage of up to 34 V with a 12.5 mV change. In addition, it integrates a power MOSFET and a current DAC to facilitate accurate detection of the GaN PA quiescent drain current. This advantage, along with its built-in configurability, allows it to bias various types of GaN Pas in numerous markets, such as satellite communications, cellular 5G, radar, and more, as shown in Figure 3.

Figure 3: ACT41000 block diagram, and supported GaN PA applications.

Biasing GaN PAs with a power management device such as the ACT41000 addresses various challenges in maintaining system performance. To learn more about how to use the ACT41000 in GaN PA applications, visit Qorvo’s short video tutorial video.