Digital Envelope Tracker Switching to Suppress LC Filter Peaking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital envelope trackers for RF power amplifiers face a contradiction between minimizing supply filter losses and preventing peaking, as lossless filters tend to peak and ring, violating voltage requirements.
Innovation Solution
A digital envelope tracker with a low-loss and high-Q supply filter is implemented, using a snubber network to reduce peaking by dissipating ringing energy, and employing a level selection circuitry that schedules secondary switching events to generate a filter response with smaller peaking, thereby reducing AC losses and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a lossless LC filter is used in the supply filter, then the efficiency of the overall envelope tracking is improved, but the filter peaks and rings causing voltage violations
Solution Approach 1:
A damping network is introduced as an intermediary element between the LC filter components. This damping network acts as a mediator that absorbs the excessive energy causing peaking and ringing, allowing the LC filter to maintain its low-loss characteristics while preventing voltage violations through the controlled energy dissipation of the damping network.
Solution Approach 2:
The invention changes the parameters of the filter by introducing resistance elements with specific values that optimize the balance between loss and peaking suppression. By carefully selecting the resistance values in the damping network, the system achieves minimal power loss while effectively controlling the peaking behavior to comply with voltage requirements.
2Reliability
If damping elements are added to reduce peaking, then voltage requirement compliance is improved, but the efficiency of the overall envelope tracking decreases
Solution Approach 1:
The invention optimizes the parameters of the damping network by carefully selecting resistance values that minimize power loss while achieving sufficient peaking reduction. The parameter optimization ensures that the damping elements provide just enough suppression to comply with voltage requirements without excessive energy dissipation that would reduce overall efficiency.
Solution Approach 2:
The damping network serves as an intermediary that provides controlled energy dissipation only when needed to suppress peaking, rather than continuously dissipating energy. This allows the system to maintain high efficiency during normal operation while providing reliability protection when peaking occurs.
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 achieves low peaking at the supply filter output without a snubber resistor, reducing power consumption and increasing efficiency, while allowing for a simpler supply filter topology.
Implementation Method 1
using a snubber network to reduce peaking by dissipating ringing energy
Implementation Method 2
A supply filter (e.g. a passive filter) between the switch and the PA power amplifier input is used to smoothen the transition from one voltage level to another, to achieve low out-of-band noise levels
Data Source
AI summary
A digital envelop tracker for a power amplifier. The digital envelop tracker includes a supply filter for filtering a supply voltage to a power amplifier, a level selection circuitry configured to determine a level of supply voltage based on an instantaneous power of an input data stream, schedule a series of switching events based on the determined level of supply voltage, and generate a level select signal based on the scheduled series of switching events, and a switch for connecting one of supply voltages to the supply filter based on the level select signal. The level selection circuitry schedules a primary switching event of the switch based on the determined level of supply voltage and secondary switching events of the switch delayed with respect to the primary switching event based on the determined level of supply voltage to generate a filter response of the supply filter with smaller peaking.