What is SuPA?
This presentation provides an overview of Supply for Power Amplifier (SuPA), including key benefits and characteristics.
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What is SuPA? Today you will get an understanding of what SuPA is, the benefits it provides, and how it's different than a standard Buck converter. My name's David van Schravendijk, and I'm a product marketing engineer for the RF power group of Texas Instruments in Silicon Valley.
SuPA stands for Supply for Power Amplifier. When designing a mobile device, the RF front end is a key factor that can influence your customers' user experience. With a SuPA, you can significantly increase battery life, performance, and help your mobile device fit into a small compact size.
As shown on the left side, the traditional approach shows a power amplifier that is connected directly to the battery, which leads to less efficiency and wasted heat. On the right side, the more efficient approach uses a SuPA to provide an adaptive supply between the battery and the power amplifier to provide significant efficiency and heat improvements.
Let's review the main benefits of using a SuPA. First, SuPA or Supply for Power Amplifiers provides reduced battery current draw. Typical RF power amplifiers have efficiencies between 4% and 40%.
This can result in a lot of wasted power and the need for a large, expensive battery. SuPA's solution is from Texas Instruments can reduce battery current by 20% to 50%. This leads to longer battery life and more time for voice and data usage.
A second benefit that a SuPA provides is improved thermal performance. When a power amplifier is transmitting voice or large amounts of data, it can create a lot of excess heat. This can reduce reliability and require a larger design to dissipate the excess heat. SuPA solutions from TI can reduce the worst case hot temperature by 30 degrees Celsius. This leads to reduced thermal constraints, better reliability, and the ability to have smaller, thinner mobile device designs.
Now that you know what SuPA is and understand the benefits, you may be interested in the key characteristics of a SuPA. There are some key differences between standard DC to DC converters and SuPAs, including higher switching frequencies to allow small sizes, higher efficiencies, high transient times, and lower output ripple. Bypass mode to allow fast transient response in high load conditions. And ACLR and other RF compliances that are necessary in mobile and RF products.
Let's compare the two side by side. A typical digital core Buck has no V control pin needed to change the output voltage, while a SuPA has a critical control pin for changing its output voltage. A typical Buck usually operates at low duty cycles below 60%, while a SuPA operates over a wide range of duty cycles from 10% to 100%.
A typical Buck is designed to have high efficiency over its entire output current range, while a SuPA is designed for high efficiency over its entire output voltage range. The quiescent current of a typical digital core Buck is critical, as it spends more time in standby, while a SuPA Buck is powering a power amplifier, which is usually under constant load.
Digital core Bucks are current limit designed to support maximum output current, while SuPA Bucks are designed for fast Vcon transients and maximum output current. A digital core Buck is optimized for line and load transients, while a SuPA Buck is optimized for Vcon transients.
The startup time is a critical difference between the two, as digital core Bucks usually aim to have below a 700 micro-second start time, while SuPA are much lower at less than 50 microseconds. Lastly, SuPA Bucks are designed to provide low output ripple and smooth transitions while dropout is not critical in digital core Bucks.
Thank you for listening. You should now understand what SuPA is, the benefits it provides, and how it's different from a standard Buck converter. For more information, please go to www.ti.com/rfpower.