Envelope Tracking Circuit Notch Filtering for RF Voltage Ripple
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Solution Overview
Problem
Existing power management circuits in 5G-NR wireless communication devices face challenges in reducing voltage ripple within the modulation bandwidth, which leads to undesirable errors in RF signals due to output impedance interactions with load currents, affecting battery life and RF signal quality.
Innovation Solution
Incorporating a notch circuit within the envelope tracking integrated circuit (ETIC) that resonates at a specific frequency within the modulation bandwidth to reduce voltage ripple, combined with a smaller decoupling capacitor and a voltage modulation circuit with feedback mechanisms to minimize output impedance and improve rate of change of the modulated voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional power management circuit uses a larger decoupling capacitor to reduce voltage ripple, then voltage ripple is reduced, but the rate of change of modulated voltage decreases and battery life is shortened
Solution Approach 1:
The patent divides the voltage ripple reduction function into two separate mechanisms: a smaller decoupling capacitor for high-frequency ripple and a notch circuit for specific frequency ranges within the modulation bandwidth. This segmentation allows each component to be optimized for its specific function, enabling fast voltage changes while reducing overall voltage ripple.
Solution Approach 2:
The notch circuit acts as an intermediary element that specifically targets and reduces voltage ripple at problematic frequencies within the modulation bandwidth without affecting the overall rate of change of the modulated voltage. This intermediary approach allows selective ripple reduction while maintaining system performance.
2Use of energy by moving object
If output impedance is increased to improve battery life, then energy efficiency improves, but voltage ripple increases causing RF signal errors
Solution Approach 1:
The patent changes the impedance characteristics dynamically by using a notch circuit that resonates at specific frequencies within the modulation bandwidth. This allows the circuit to present different impedance characteristics at different frequencies, reducing voltage ripple at problematic frequencies while maintaining higher overall output impedance for battery life extension.
3Object-affected harmful factors
If voltage ripple is reduced using traditional methods, then RF signal quality improves, but the circuit complexity increases
Solution Approach 1:
Instead of applying a universal voltage reduction approach across the entire modulation bandwidth, the notch circuit applies localized impedance modification at specific frequency ranges where voltage ripple problems occur. This local quality approach reduces RF signal errors only where needed, minimizing unnecessary circuit complexity.
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 solution effectively minimizes root-mean-square (RMS) error vector magnitude (EVM) and prolongs battery life by reducing voltage ripple, achieving a defined performance threshold while supporting fast voltage changes between OFDM symbols.
Implementation Method 1
The notch circuit is configured to resonate at a notch frequency within a modulation bandwidth of the RF signal to reduce the voltage ripple
Data Source
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AI summary
Voltage ripple reduction in a power management circuit is disclosed. The power management circuit includes a power amplifier circuit configured to amplify a radio frequency (RF) signal based on a modulated voltage and an envelope tracking integrated circuit (ETIC) configured to provide the modulated voltage to the power amplifier circuit via a conductive path. Notably, an output impedance presenting at an input of the power amplifier circuit can interact with a modulated load current in the power amplifier circuit to create a voltage ripple in the modulated voltage to potentially cause an undesirable error in the RF signal. In this regard, a notch circuit is provided, preferably in the ETIC, to reduce the voltage ripple within a modulation bandwidth of the RF signal. As a result, it is possible to minimize the undesirable error, such as root-mean-square (RMS) error vector magnitude (EVM), within the modulation bandwidth of the RF signal.