Envelope Tracking Circuitry for RF Amplifier Power Efficiency
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Solution Overview
Problem
Wireless communications circuitry in electronic devices consumes excessive energy due to the need for large dynamic range supply voltages to accommodate varying RF signal amplitudes, leading to inefficiency and reduced battery life.
Innovation Solution
The envelope power supply circuitry includes power converter and tracking circuitry that adjusts the supply voltage based on input power levels, limiting the dynamic range when possible to reduce energy consumption, while maintaining amplifier gain consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large dynamic range supply voltage is used to accommodate varying RF signal amplitudes, then the amplifier can handle the full amplitude range, but energy consumption increases
Solution Approach 1:
The supply voltage is made dynamic rather than static, allowing it to adapt to the instantaneous amplitude of the RF signal. The envelope tracking circuitry continuously adjusts the supply voltage to match the signal envelope, providing high voltage only when needed for peak amplitudes and lower voltage during low-amplitude periods, thus resolving the contradiction between handling full amplitude range and reducing energy consumption
Solution Approach 2:
The supply voltage parameter is changed from a constant value to a time-varying parameter that tracks the signal envelope. By modulating the supply voltage according to the instantaneous signal amplitude, the system achieves both full amplitude range coverage and reduced energy consumption, as the voltage parameter adapts to match actual signal requirements
2Adaptability or versatility
If the supply voltage is set based on the worst-case scenario (largest possible amplitude range), then all RF signals can be accommodated, but the dynamic range of the envelope power supply signal becomes unnecessarily large, degrading efficiency
Solution Approach 1:
The envelope tracking system uses the RF signal itself to control the supply voltage. The signal envelope automatically determines the required voltage level, eliminating the need for external worst-case sizing. The system serves itself by using the signal's own characteristics to regulate the power supply, achieving both universal signal accommodation and improved efficiency without unnecessary voltage headroom
3Loss of energy
If envelope tracking is implemented to increase efficiency, then power consumption decreases, but the dynamic range requirements for the power supply circuitry increase
Solution Approach 1:
The power supply is segmented into multiple voltage levels or ranges that can be selectively applied. Rather than requiring a single high-dynamic-range power supply, the system divides the voltage requirements into segments, using lower voltage for most operating conditions and only accessing higher voltage segments when the signal envelope demands it, thus reducing overall dynamic range requirements while maintaining efficiency benefits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach decreases energy consumption by reducing the supply voltage, thereby extending battery life without significant impact on performance or introducing excessive distortion.
Implementation Method 1
The power converter circuitry is configured to receive an envelope power converter control signal and a supply voltage and provide an envelope power supply signal for an amplifier from the supply voltage and based on the envelope power converter control signal
Implementation Method 2
Envelope tracking involves modulating a supply voltage provided to an amplifier based on the instantaneous magnitude (i.e., the envelope) of an RF input signal provided to the amplifier
Data Source
AI summary
Envelope power supply circuitry includes power converter circuitry and envelope tracking circuitry. The power converter circuitry is configured to receive an envelope power converter control signal and a supply voltage and provide an envelope power supply signal for an amplifier from the supply voltage and based on the envelope power converter control signal. The envelope tracking circuitry is coupled to the power converter circuitry. In a first mode of operation, the envelope tracking circuitry is configured to provide the envelope power converter control signal such that a gain of the amplifier remains substantially constant over a range of input power provided to the amplifier. In a second mode of operation, the envelope tracking circuitry is configured to limit the dynamic range of the envelope power supply signal.