Fast-Switching PMIC for 5G RF Power Amplifiers
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Solution Overview
Problem
Wireless communication devices face challenges in maintaining efficient power management, particularly in 5G-NR systems, due to the need for rapid voltage changes between OFDM symbols, which can lead to battery drain and operational inefficiencies.
Innovation Solution
A fast-switching power management integrated circuit (PMIC) that provides average power tracking (APT) voltage to power amplifier circuits, enabling rapid voltage transitions within 20 nanoseconds with reduced inrush current, using a voltage amplifier and offset circuit to maintain voltage levels and reduce ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid voltage changes are implemented between OFDM symbols to meet 5G-NR requirements, then signal transmission performance is improved, but battery drain increases and power efficiency deteriorates
Solution Approach 1:
The PMIC performs preliminary voltage adjustment during the cyclic prefix period before the actual OFDM symbol transmission begins. By preparing the voltage transition in advance during the guard period, the system achieves rapid voltage switching without extending into the active transmission period, thereby maintaining power efficiency while meeting the speed requirements for 5G-NR operations
Solution Approach 2:
The voltage transition is executed rapidly during the brief cyclic prefix interval by applying accelerated switching control. The PMIC utilizes the short available time window to complete the voltage change from present level to future level through high-speed switching mechanisms, achieving the required transition speed without impacting the main signal transmission period
2Loss of time
If voltage transition time is reduced to meet CP duration requirements, then OFDM symbol switching performance is improved, but voltage stability and ripple control deteriorate
Solution Approach 1:
An offset circuit is introduced as an intermediary component between the voltage source and the power amplifier. This offset circuit generates a compensating voltage signal that counteracts the ripple and transient effects during rapid voltage transitions. By adding this intermediary stage, the system achieves fast voltage switching while the offset compensation maintains voltage stability and prevents excessive ripple during the transition interval
Solution Approach 2:
The PMIC dynamically adjusts voltage parameters during the transition by changing from a present voltage level to a future voltage level within the CP duration. The system modifies the voltage transition profile to complete the change rapidly while incorporating ripple reduction techniques that maintain stability throughout the transition process
Data Source
AI summary
A fast-switching power management integrated circuit (PMIC) is provided. The PMIC is configured to provide an average power tracking (APT) voltage to a power amplifier circuit for amplifying a radio frequency (RF) signal modulated in multiple time intervals. Herein, the PMIC is configured to increase or decrease the APT voltage from a present voltage level in a present one of the time intervals to a future voltage level in an upcoming one of the time intervals with very short switching interval (e.g., <20 nanoseconds). When the APT voltage transitions from the present voltage level to the future voltage level, the PMIC opportunistically activates a voltage amplifier to help ensure proper operation of the power amplifier circuit (e.g., maintain the APT voltage at the present level and reduce ripple in the APT voltage). As a result, the PMIC can switch the APT voltage frequently and rapidly with reduced inrush current.