Differential Amplifier Harmonic Suppression With Switchable Resonance
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Solution Overview
Problem
Differential amplifier circuits struggle to prevent second harmonics from being outputted without affecting fundamental signals, which is crucial for achieving ideal class-F operation and reducing power consumption.
Innovation Solution
Incorporating resonant circuits with specific resonant frequencies corresponding to second harmonic frequencies, utilizing inductors and capacitors in series and parallel configurations, and a switch to control the load impedance, preventing second harmonics from being outputted while maintaining fundamental signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a differential amplifier circuit uses a simple output structure without harmonic suppression, then the device complexity is reduced, but second harmonics are outputted affecting signal quality
Solution Approach 1:
The patent introduces resonant circuits as intermediary elements between the differential amplifier output and the load. These resonant circuits act as mediators that selectively interact with second harmonic frequencies, presenting high impedance to block them while maintaining low impedance at fundamental frequencies, thus suppressing harmful harmonics without complicating the overall amplifier structure
Solution Approach 2:
The patent changes the impedance parameters of the output circuit by incorporating resonant circuits with specific resonant frequencies. By adjusting the resonant frequency parameters of these circuits to match the second harmonic frequency, the circuit dynamically alters its impedance characteristics to suppress harmonics while maintaining fundamental signal transmission
2Use of energy by moving object
If the differential amplifier operates in class-F mode to reduce power consumption, then energy efficiency is improved, but second harmonics are not suppressed affecting operation quality
Solution Approach 1:
The patent converts the harmful second harmonic generation inherent in class-F operation into a beneficial feature by using resonant circuits to resonate at these frequencies. The resonant circuits transform the unwanted harmonic energy into a controlled phenomenon that can be suppressed through impedance matching, allowing class-F operation to maintain both efficiency and signal quality
3Object-generated harmful factors
If resonant circuits are added to suppress second harmonics, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent designs resonant circuits that serve multiple functions simultaneously: they suppress second harmonics, maintain fundamental signal transmission, and can be integrated with existing amplifier output structures. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity while achieving harmonic suppression
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
Effectively prevents second harmonics from being outputted, allowing for ideal class-F operation and reduced power consumption by short-circuiting load impedances at resonant frequencies, thereby enhancing the efficiency of the differential amplifier circuit.
Implementation Method 1
the first inductor or the second inductor is connected in series with the first capacitor to form a resonant circuit having a first resonant frequency, and the first inductor or the second inductor is connected in series with the first capacitor and the second capacitor that are connected in parallel to form a resonant circuit having a second resonant frequency
Data Source
AI summary
A differential amplifier circuit includes a first and second amplifiers that output a differential signal in a radio-frequency band, a first inductor having a first end connected to an output end of the first amplifier, a second inductor having a first end connected to an output end of the second amplifier, a choke inductor connected to second ends of the first and second inductors, a first and second capacitors, and a switch that connects the second capacitor in parallel to the first capacitor or terminates a parallel connection of the first and second capacitors. A resonant circuit formed by connecting the first or second inductor in series with the first capacitor has a different resonant frequency from a resonant circuit formed by connecting the first or second inductor in series with the parallel-connected first and second capacitors. These resonant frequencies correspond to second harmonic frequencies of the differential signal.