Qualcomm Envelope Power Tracker and PA Manufacturers

This article explores the Qualcomm Envelope Power Tracker QET5100 and its features. We’ll also touch upon some of the leading manufacturers of Envelope Tracking power amplifiers (PAs).

What is Envelope Tracking?

Modern wireless systems rely on complex modulation techniques like QAM and OFDM, where the amplitude of the waveform changes over time – unlike FM and PM modulation. Traditional RF amplifiers are often operated in a compression region to maximize efficiency. This approach works well when the amplifier input signal amplitude is relatively constant, as is the case with FM/PM modulated signals.

Waveform Without Envelope Tracking

However, in amplitude-modulated systems, there can be a significant difference between the amplifier’s signal input and its supply voltage. This can lead to undesirable over-voltage situations for the amplifier, resulting in wasted power and reduced overall efficiency. Remember, efficiency is the ratio of power output to DC power input.

Envelope Tracking

Envelope tracking addresses this issue by dynamically adjusting the power supply to the PA based on the envelope of the time-varying input signal. In essence, a higher DC supply is provided during signal peaks (maxima) and a lower DC supply during signal troughs (minima). This allows for achieving peak efficiency.

RF Front End with power tracker Image Courtesy : Qualcomm Technologies, Inc.

As shown in the image above, the modem is responsible for baseband signal generation and analysis. It employs a DAC (Digital-to-Analog Converter) in the transmit path and an ADC (Analog-to-Digital Converter) in the receive path. The envelope power tracker receives input from the modem’s DAC and provides a proportional DC voltage to the PA (Power Amplifier).

Using an envelope power tracker in the RF front-end system brings several advantages, including increased battery life, improved amplifier efficiency, and better compliance with EVM/ACPR (Error Vector Magnitude/Adjacent Channel Power Ratio) specifications for wireless systems.

Refer to a tutorial on Envelope Tracking Basics for more information.

Qualcomm Envelope Power Tracker QET5100

Here are some key features of the Qualcomm Envelope Power Tracker (QET5100):

• It’s integrated into Qualcomm Snapdragon modems, commonly found in LTE and 5G mobile phones.
• It supports 60 MHz envelope tracking for up to three uplink carrier aggregation channels.
• It works in conjunction with the modem to deliver power-efficient connectivity in mobile devices.
• It provides cost-optimized RF front-end solutions.

Envelope Tracking Power Amplifier Manufacturers

The following table lists some prominent manufacturers of Envelope Power Trackers and envelope tracking power amplifiers (PAs):