Doherty Amplifier TIP Cells for Adjustable Alpha at 90° Phase
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Solution Overview
Problem
Conventional Doherty amplifiers have a fixed alpha factor, which is not beneficial across different modulation schemes, leading to poorer power added efficiency (PAE) at high peak to average power ratios in modern wireless communication systems.
Innovation Solution
A Doherty amplifier circuit with a tunable impedance and phase circuit, allowing for an adjustable alpha factor, which optimizes power added efficiency (PAE) for different modulation schemes and power levels by maintaining a 90° phase shift with minimal variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed alpha factor is used in conventional Doherty amplifiers, then the circuit structure is simple, but power added efficiency deteriorates at high peak to average power ratios in modern wireless communication systems
Solution Approach 1:
The patent applies the dynamics principle by making the alpha factor adjustable rather than fixed. The Doherty amplifier includes a tuning network with variable components (such as variable capacitors or inductors) that allow the alpha factor to be dynamically adjusted according to different modulation schemes and operating conditions. This enables the amplifier to optimize power added efficiency for various peak-to-average power ratios while maintaining a relatively simple basic circuit structure.
2Loss of energy
If the alpha factor is adjusted for different modulation schemes, then power added efficiency improves, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by adjusting the alpha factor parameter to match different modulation schemes and operating conditions. The tuning network allows modification of electrical parameters (impedance values, phase shifts) without fundamentally changing the amplifier's circuit topology. This enables optimization of power added efficiency for various wireless communication standards while keeping the device complexity manageable through parameter adjustment rather than structural redesign.
Data Source
AI summary
A Doherty amplifier circuit having a tunable impedance and phase (“TIP”) circuit to provide an adjustable alpha factor, which allows for a selection of power added efficiency (PAE) curves that are useful for applications having different modulations or to meet other criteria. Embodiments include a Doherty amplifier having a TIP circuit that provides for tunability of the impedance ZINV (resulting in an adjustable alpha factor) while maintaining the phase of the output of the carrier amplifier at 90° (for a selected polarity)±a low phase variation. Embodiments of the TIP circuit include one or more series-connected TIP cells comprising at least one TIP circuit combined with a tunable phase adjustment circuit. In operation, when the impedance of a TIP cell is adjusted, adjustments within the cell are also made to provide a phase shift correction back towards 90° (at the selected polarity).