Dual-Frequency Doherty Amplifier With 90° Compensation Circuit
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Solution Overview
Problem
Conventional Doherty amplifiers are limited to a single operation frequency, requiring multiple amplifiers and a switch to amplify signals over a wide band, resulting in a large and complex circuit.
Innovation Solution
A Doherty amplifier configuration with specific electrical lengths for input and output circuits, along with a compensation circuit and controller to switch amplification classes, enabling amplification of signals at two operation frequencies without multiple amplifiers or a switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple Doherty amplifiers with different operation frequencies are used to amplify signals over a wide band, then the applicable frequency range is improved, but the circuit size and complexity increase due to requiring switches and multiple amplifiers
Solution Approach 1:
The patent applies universality by designing a single Doherty amplifier that can operate at multiple frequencies (first operation frequency and second operation frequency which is half of the first). The amplifier structure includes circuits with specific electrical lengths that enable it to function across different frequency bands without requiring separate amplifiers for each frequency, thus reducing circuit complexity while maintaining wide frequency applicability
Solution Approach 2:
The patent utilizes parameter changes by adjusting the electrical lengths of input and output circuits to specific values (180×n degrees and 90 degrees at the first operation frequency) that allow the same amplifier structure to operate effectively at both the first operation frequency and its half frequency. This parameter optimization enables frequency adaptability without increasing device complexity
2Adaptability or versatility
If a switch is included to switch between multiple Doherty amplifiers depending on operation frequency, then the ability to amplify signals at different frequencies is improved, but the device complexity and number of components increase
Solution Approach 1:
The patent extracts and eliminates the switch component from the system by designing an amplifier that inherently supports multiple frequencies through its circuit structure. Instead of using a switch to select between different amplifiers, the single amplifier is designed with input and output circuits having specific electrical lengths that naturally accommodate both frequency operations, thereby removing the need for additional switching components
Solution Approach 2:
The patent merges the functionality of multiple frequency-specific amplifiers into a single unified amplifier structure. By combining the capability to amplify at both the first operation frequency and its half frequency within one amplifier unit with properly designed input and output circuits, the system eliminates the need for separate amplifiers and switches, reducing overall device complexity
Data Source
AI summary
Included is a compensation circuit having one end connected to another end of a first output circuit and another end of a second output circuit and another end grounded, the compensation circuit having an electrical length of 90 degrees at a first operation frequency and an electrical length of 45 degrees at a second operation frequency which is half of the first operation frequency.