Power Amplifier Harmonic Cancellation via Delayed Path Interference
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Solution Overview
Problem
RF power amplifiers generate unwanted harmonics, leading to increased complexity and cost in external harmonic filtering networks, and potential self-interference with other circuits.
Innovation Solution
The power amplifier system divides the amplification into two matched paths with a delay element in one path relative to the other, allowing for cancellation of harmonic energy by adjusting the delay to specific values, thereby reducing the order of the external matching network and attenuating unwanted harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If external harmonic filtering networks are used to reduce unwanted harmonics, then harmonic attenuation is improved, but device complexity and product cost increase due to large order filters and higher parts counts
Solution Approach 1:
The power amplifier is divided into two separate matched amplification paths (first and second paths) with identical components but different delay settings. Each path processes the input signal independently with a different delay element value, and their outputs are combined to achieve harmonic cancellation through destructive interference, eliminating the need for complex external filtering networks
Solution Approach 2:
The patent converts the harmful harmonic energy into a beneficial effect by using the same harmonic generation mechanism against itself. The two amplification paths generate identical harmonics that are then canceled through destructive interference when combined, transforming the harmful harmonic energy into useful signal cancellation
2Object-generated harmful factors
If external harmonic filtering networks are used to reduce unwanted harmonics, then harmonic attenuation is improved, but manufacturing cost increases due to higher parts counts
Solution Approach 1:
The power amplifier is divided into two separate matched amplification paths (first and second paths) with identical components but different delay settings. Each path processes the input signal independently with a different delay element value, and their outputs are combined to achieve harmonic cancellation through destructive interference, eliminating the need for complex external filtering networks
Solution Approach 2:
The patent changes the delay parameter (Td) of one amplification path relative to the other to achieve harmonic cancellation. By adjusting the delay element value in the second path to be different from the first path while keeping other components matched, the system achieves frequency-selective harmonic attenuation without requiring additional filtering components
3Object-generated harmful factors
If high order filtering networks are used to reduce unwanted harmonics, then harmonic attenuation is improved, but the harmonics self-interfere with other circuits creating additional problems
Solution Approach 1:
The patent converts the harmful harmonic energy into a beneficial effect by using the same harmonic generation mechanism against itself. The two amplification paths generate identical harmonics that are then canceled through destructive interference when combined, transforming the harmful harmonic energy into useful signal cancellation
Solution Approach 2:
The delay element acts as an intermediary that introduces a controlled time difference between the two amplification paths. This delay difference causes the harmonic signals from each path to be out of phase when combined, enabling destructive interference and cancellation of unwanted harmonics while the fundamental signal remains constructively added
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 approach achieves significant attenuation of harmonics with minimal loss in fundamental power, reducing the complexity and cost of harmonic filtering networks while minimizing interference with other circuits.
Implementation Method 1
a delay element in one path relative to the other, allowing for cancellation of harmonic energy by adjusting the delay to specific values
Implementation Method 2
allowing for cancellation of harmonic energy by adjusting the delay to specific values, thereby reducing the order of the external matching network and attenuating unwanted harmonics
Data Source
AI summary
In one form, a power amplifier system includes first and second amplification path, and a combination element. The first amplification path has an input for receiving a drive signal, and an output. The second amplification path has an input coupled to the input of the first amplification path, and an output. The second amplification path has a delay element that inserts a signal path delay with respect to the first amplification path, wherein the delay element has a delay corresponding to a harmonic that is desired to be reduced. The combination element is coupled to the output of the first amplification path and an output of the second amplification path, and provides an output signal as a sum of outputs of the first amplification path and the second amplification path.