Parallel Amplifier Modulation With Stepped Waveform Harmonic Reduction
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Solution Overview
Problem
Existing modulated signal generating devices that use parallel amplifiers for transmitting modulated signals produce rectangular waveforms, requiring band-pass filters to remove harmonic components, which is inefficient.
Innovation Solution
A modulated signal generating device that includes a determining unit, a control signal generating unit, and a combiner, which determines the number of amplifiers to drive based on the input signal's amplitude and fluctuation, generating control signals to produce a stepwise waveform output, thereby reducing harmonic components without the need for band-pass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If on-off control is performed on amplifiers according to carrier signal frequency, then amplitude modulation is achieved, but rectangular waveform is generated requiring band-pass filter
Solution Approach 1:
The patent applies dynamics by making the control period variable and adaptive. The control period is set to be shorter than the period of the input signal and is dynamically adjusted based on signal characteristics. This dynamic control approach transforms the static rectangular waveform into a stepped waveform with reduced harmonics, eliminating the need for band-pass filters while maintaining amplitude modulation capability.
Solution Approach 2:
The patent changes the parameter of control period from being equal to or longer than the input signal period to being shorter than the input signal period. This parameter change fundamentally alters the waveform shape from rectangular to stepped, reducing harmonic components and eliminating the need for additional filtering components.
2Manufacturing precision
If band-pass filter is used to remove harmonic components, then signal quality is improved, but device size and complexity increase
Solution Approach 1:
The patent converts the harmful rectangular waveform with high harmonics into a beneficial stepped waveform by using short-period on-off control. The rapid switching creates a waveform that naturally approximates the desired sinusoidal shape through harmonic cancellation, turning the previously harmful harmonic-rich rectangular wave into a useful stepped waveform that requires no additional filtering.
3Power
If amplifiers operate continuously at high power, then output power is maintained, but heat generation and device lifespan are affected
Solution Approach 1:
The patent employs periodic on-off control of amplifiers with control periods shorter than the input signal period. This periodic switching allows amplifiers to operate in pulses rather than continuously, reducing average power dissipation and heat generation while maintaining the required output power through constructive combination of amplified pulses.
4Manufacturing precision
If control period is shorter than input signal period, then harmonic components are reduced, but control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-setting the control period to be shorter than the input signal period before the modulation process begins. This pre-determined timing relationship simplifies the control mechanism, as the controller only needs to generate periodic control signals at the predetermined short period without complex real-time calculations, reducing control complexity while maintaining waveform accuracy.
Data Source
AI summary
According to an embodiment, the modulated signal generating device modulates an input signal and generates an output signal. The modulated signal generating device includes a plurality of amplifiers, a combiner, a determining unit and a control signal generating unit. The plurality of amplifiers connects in parallel with one another and each configures to drive based on a control signal and to generate amplified signals. The combiner configures to combine the amplified signals and to obtain the output signal having a stepwise waveform. The determining unit configures to determine number of amplifiers to be driven based on a value of the input signal in a period shorter than a period of the input signal. The control signal generating unit configures to select zero or more amplifiers to be driven from among the amplifiers, based on the number of amplifiers determined by the determining unit, the value of the input signal, and a fluctuation in the value of the input signal, and to generate the control signal for driving the selected amplifier.