Polar Transmitter Tunable Matching for Wideband Back-Off Efficiency
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Solution Overview
Problem
Current wideband power amplifier designs suffer from poor back-off efficiency, even with advanced matching networks, and require a solution for improved power efficiency across multiple communication standards while maintaining a compact size.
Innovation Solution
A novel feed-forward architecture with a dynamic-matching network in a digital polar transmitter is introduced, which optimizes matching modes under various amplitude and frequency conditions, using a tunable matching network and switched capacitors to enhance saturated and back-off power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed matching network is used in the transmitter, then the device complexity is reduced, but the bandwidth is limited and power efficiency at different operating points deteriorates
Solution Approach 1:
The patent implements a dynamic matching network that automatically adjusts its impedance transformation ratio based on the operating frequency and power level. The matching network transitions from a fixed configuration to a dynamically adjustable one, enabling optimal impedance matching across wide frequency ranges and at different back-off power levels, thereby resolving the contradiction between bandwidth adaptability and device complexity.
Solution Approach 2:
The patent changes the electrical parameters of the matching network by introducing adjustable impedance transformation ratios. The matching network can dynamically alter its transformation ratio to match different load conditions and frequency points, enabling the transmitter to maintain high efficiency across a wide bandwidth without requiring multiple fixed matching networks.
2Adaptability or versatility
If multiple inductors are used for inter-stage/output-stage matching in wideband PA, then the bandwidth is extended, but the power efficiency is sacrificed
Solution Approach 1:
The patent replaces static multi-inductor matching networks with a dynamic matching network that adjusts its characteristics in real-time. This dynamic approach enables the system to achieve wideband performance through adaptive impedance transformation rather than relying on multiple fixed inductors, thereby maintaining bandwidth while improving power efficiency by eliminating the losses associated with fixed inductor-based matching.
3Loss of energy
If a dual-modes or multiple modes matching network is used, then the back-off efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent implements a universal matching network that can operate in multiple modes through a single integrated structure. The dynamic matching network is designed to provide optimal matching for both saturated and back-off power levels, as well as across different frequency points, using one unified circuit rather than separate dual-mode or multi-mode networks, thereby reducing overall device complexity while maintaining high back-off efficiency.
Data Source
AI summary
A polar transmitter includes an amplitude path comprising an amplitude signal that corresponds to an amplitude of a vector sum of an in-phase input signal and a quadrature input signal; a phase path comprising a phase modulator configured to phase-modulate a phase signal that corresponds to the phase of the vector sum of the in-phase input signal and the quadrature input signal; a digital power amplifier (DPA) configured to amplify the phase-modulated (PM) input signal based on the amplitude signal; a tunable matching network coupled to an output of the DPA and configured to adjust a load impedance of the DPA; and a controller configured to adjust the matching network based on a look-up table with respect to amplitude and frequency information, where the look-up table indicates a plurality of optimal operation modes of the matching network for specific combinations of amplitude and frequency information.