Delay-Compensated Envelope Tracking Voltage for RF Power Amplifiers
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Solution Overview
Problem
Conventional envelope tracking power supplies for RF signals often fail to synchronize adequately with RF signals, leading to excessive power consumption, compression, and clipping, especially in high-bandwidth applications like 5G and mmWave, due to inherent delays in generating the target supply voltage.
Innovation Solution
The implementation of envelope tracking power supply circuitry that includes envelope synchronization circuitry to adjust the target supply voltage based on delay measurements, impedance compensation circuitry to cancel source impedance voltage, and adder circuitry to provide a synchronized envelope tracking supply voltage, ensuring accurate synchronization with the RF signal power envelope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If envelope tracking power supply generates target supply voltage to track RF signal power envelope, then power efficiency and linearity of RF power amplifier are improved, but time delay in generating target supply voltage causes synchronization failure leading to excessive power consumption, compression, and clipping
Solution Approach 1:
The patent applies preliminary action by measuring the time delay between the RF signal and the generated target supply voltage, then using this measurement to predictively adjust the phase of the target supply voltage. This allows the envelope tracking power supply to proactively compensate for the inherent generation delay, aligning the supply voltage with the RF signal power envelope before synchronization failure occurs, thereby reducing power consumption while maintaining timing accuracy
Solution Approach 2:
The patent implements feedback by continuously measuring the time delay between the RF signal and the generated target supply voltage, then using this feedback information to adjust the phase of the target supply voltage. The delay measurement circuitry monitors the timing relationship and feeds this information back to the phase adjustment mechanism, creating a closed-loop system that maintains synchronization and optimizes power efficiency
2Power
If envelope tracking power supply provides supply voltage to RF power amplifier, then RF signal amplification is enabled, but output impedance of power supply interacts with input impedance of amplifier causing voltage modulation and performance degradation
Solution Approach 1:
The patent applies the intermediary principle by introducing an impedance compensation circuit between the envelope tracking power supply and the RF power amplifier. This intermediary circuit measures the output voltage of the power supply and generates a compensation signal that counteracts the harmful voltage modulation caused by impedance interaction. The compensation circuit acts as a mediator that isolates the power supply from the amplifier's input impedance effects, maintaining stable operation and preventing performance degradation
Data Source
AI summary
Envelope tracking power supply circuitry includes a look up table (LUT) configured to provide a target supply voltage based on a power envelope measurement. The target supply voltage is dynamically adjusted based on a delay between the power envelope of an RF signal and a provided envelope tracking supply voltage. The envelope tracking supply voltage is generated from the adjusted target supply voltage in order to synchronize the envelope tracking supply voltage with the power envelope of the RF signal.