Doherty Amplifier TIP Circuit for Adjustable Alpha and PAE
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Solution Overview
Problem
Conventional Doherty amplifiers have a fixed alpha factor, which is not beneficial across different modulation schemes used in cellular telephone systems, leading to poorer power added efficiency (PAE) at high peak to average power ratios.
Innovation Solution
A Doherty amplifier circuit with a tunable impedance and phase circuit (TIP) that allows for an adjustable alpha factor, maintaining a 90° phase shift and optimizing PAE for different modulation schemes and power levels.
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 the power added efficiency deteriorates at high peak to average power ratios across different modulation schemes
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed alpha factor into a dynamically adjustable parameter. The Doherty amplifier incorporates control circuitry that can modify the alpha factor based on operating conditions, modulation scheme, and power level requirements. This dynamic adjustment allows the amplifier to optimize power added efficiency across different peak-to-average power ratios while maintaining operational simplicity through automated control.
Solution Approach 2:
The patent implements parameter changes by systematically varying the alpha factor parameter to match different modulation schemes and power levels. The control system adjusts the alpha factor parameter based on detected operating conditions, enabling the amplifier to adapt its efficiency characteristics. This parameter modification resolves the contradiction by allowing efficiency optimization without fundamentally changing the circuit architecture.
2Use of energy by moving object
If the alpha factor is adjusted for different modulation schemes, then power added efficiency improves across various power levels, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing a control system that handles multiple modulation schemes and power levels through a single integrated alpha factor adjustment mechanism. The control circuitry universally manages different operating conditions by selecting appropriate alpha factor values, eliminating the need for separate circuits for each modulation scheme. This multi-functional approach improves efficiency across various conditions while minimizing the increase in device complexity.
Solution Approach 2:
The patent implements self-service through automatic alpha factor adjustment based on detected operating conditions. The control system autonomously monitors power levels and modulation schemes, then automatically selects and applies the appropriate alpha factor without requiring manual intervention or complex external control. This self-adjusting capability achieves efficiency optimization while keeping the control architecture relatively simple.
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).