Staged Switch Activation in Voltage Modulators for Clean SBET
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Solution Overview
Problem
Existing radio systems face challenges in achieving fast, clean transitions in symbol-based envelope tracking (SBET) for power amplifiers, leading to excessive overshoots and power dissipation due to parasitic inductances and slow switching times.
Innovation Solution
Implementing a voltage modulator with staged activation of parallel field effect transistors, where smaller switches activate before larger ones to minimize overshoots and power dissipation, using make-before-break switching and magnetic field cancellation to achieve rapid transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional switching mechanisms are used in voltage modulators for symbol-based envelope tracking, then the power amplifier can be biased with discrete voltage levels, but excessive overshoots and power dissipation occur due to parasitic inductances and slow switching times
Solution Approach 1:
The patent segments the switching operation into multiple phases by introducing a two-stage switching mechanism. The first switch (S1) and second switch (S2) operate in sequence rather than simultaneously, dividing the voltage transition into manageable stages that reduce overshoot and power dissipation during each transition phase
Solution Approach 2:
The patent applies preliminary action by pre-charging or pre-discharging capacitive elements before the main switching event. The first switch activates to prepare the voltage level before the second switch completes the transition, ensuring that parasitic inductances do not cause excessive overshoot during the actual voltage change
2Loss of time
If faster switching is implemented to reduce transition time in symbol-based envelope tracking, then the envelope tracking accuracy improves, but electromagnetic interference and power dissipation increase due to parasitic inductances
Solution Approach 1:
The patent introduces intermediary switching elements (the first and second switches in series) that mediate the voltage transition. These intermediate switches control the rate of change of current through the parasitic inductances, reducing electromagnetic interference while maintaining fast overall transition times for accurate envelope tracking
3Power
If larger switches are used to reduce resistance and improve current handling in the voltage modulator, then the power handling capability increases, but the physical area and device complexity increase
Solution Approach 1:
The patent segments the current path through multiple switches in series (first switch and second switch) rather than using a single large switch. This segmentation allows each switch to be smaller in physical area while collectively handling the required power, reducing the total device footprint while maintaining power handling capability
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
The solution enables clean, fast transitions without significant overshoots or power dissipation, improving power amplifier efficiency and reducing electromagnetic interference.
Implementation Method 1
excessive overshoots and power dissipation due to parasitic inductances and slow switching times
Implementation Method 2
magnetic field cancellation to achieve rapid transitions
Data Source
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AI summary
Aspects of this disclosure relate to voltage modulators with staged activation of switches. A voltage modulator can receive supply voltages and provide a selected one of the supply voltages as an output voltage. The voltage modulator can include switches in parallel where one of the switches in parallel activates before another switch in parallel in association by transitioning the output voltage between different supply voltages. Embodiments of this disclosure relate to symbol-based envelope tracking. Related systems and methods are disclosed.