Doherty Power Amplifier Combiner Without Quarter-Wave Lines
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Solution Overview
Problem
Existing power amplifier circuits, particularly Doherty amplifier circuits, face limitations in increasing bandwidth while maintaining efficiency and reducing size, as they often rely on quarter wavelength lines that are not suitable for size reduction and bandwidth expansion.
Innovation Solution
The proposed power amplifier circuit employs a divider circuit that splits the input signal into multiple phases, using transformers with inductors and capacitors to create differential pairs and converters, allowing for the elimination of quarter wavelength lines and enabling wider bandwidth through optimized phase differences and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quarter wavelength line is used as the combiner in a Doherty amplifier circuit, then the circuit achieves proper signal combining and phase alignment, but the circuit size increases and bandwidth is limited
Solution Approach 1:
The patent extracts and eliminates the quarter wavelength line from the Doherty amplifier circuit. By removing this specific component, the circuit size is reduced and bandwidth is increased while the signal combining function is maintained through alternative circuit configurations using transformers and impedance matching networks.
Solution Approach 2:
The patent implements a combiner circuit that performs multiple functions: signal combining, impedance matching, and phase alignment without requiring a dedicated quarter wavelength line. The transformer-based combiner structure provides universal functionality that replaces the specialized quarter wavelength line component.
2Reliability
If a quarter wavelength line is used as the combiner, then signal combining is achieved, but the bandwidth of the power amplifier circuit is limited
Solution Approach 1:
The quarter wavelength line is removed from the circuit to eliminate its bandwidth limitations. The alternative combiner design using transformers and impedance matching networks provides wider bandwidth operation while maintaining signal combining performance.
Solution Approach 2:
The patent changes the operational parameters of the combiner by using transformer-based impedance matching instead of quarter wavelength line resonance. This parameter change enables the circuit to operate over a wider frequency range, achieving increased bandwidth while maintaining proper signal combining.
3Use of energy by moving object
If carrier and peak amplifiers are operated in saturation regions to improve power efficiency, then power efficiency increases, but distortion increases and requires complex linearization circuits
Solution Approach 1:
The patent merges the carrier amplifier and peak amplifier operations in the saturation region, using their combined output through the combiner to achieve both high power efficiency and acceptable linearity. The combiner structure itself contributes to signal reconstruction that reduces the need for additional complex linearization circuits.
Solution Approach 2:
The Doherty amplifier structure enables the amplifiers to self-linearize to some extent through their interaction in the combiner. The circuit configuration allows the amplifiers to operate in saturation while the overall system maintains acceptable linearity without requiring external complex linearization circuits, achieving self-service functionality.
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 configuration achieves a significant increase in fractional bandwidth, up to 39.4%, while reducing the circuit size and improving power efficiency by operating the carrier and peak amplifiers in saturation regions based on input signal power levels.
Implementation Method 1
a first converter that includes a first transformer including a first inductor and a second inductor, a capacitor connected in parallel with the first inductor, and a capacitor connected in parallel with the second inductor
Data Source
AI summary
A divider circuit divides an input signal into first, second, third, and fourth input signals. A first carrier amplifier amplifies the first input signal and outputs a first output signal. A first peak amplifier amplifies the second input signal and outputs a second output signal. A first converter inputs the first and second output signals. A second carrier amplifier amplifies the third input signal and outputs a third output signal, the first and second carrier amplifiers forming a differential pair. A second peak amplifier amplifies the fourth input signal and outputs a fourth output signal, the first and second peak amplifiers forming a differential pair. A second converter inputs the third output signal and is electrically connected to the first converter. A combiner is electrically connected to an output terminal or a ground and to the first and second converters.