Phase and Pulse-Width Modulation for Saturated RF Amplifiers

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Solution Overview

Problem

Amplifiers used in digital signal transmission consume excessive power when operating in the linear region, and existing saturated amplifier technologies do not efficiently manage power consumption during non-transmission periods.

Innovation Solution

A system and method that provides amplitude and phase modulation of digital signals using selectively delayed and pulse-width-modulated signals, allowing saturated amplifiers to operate only during pulse transmission, reducing power consumption by using a combination of delay lines for phase modulation and pulse width adjustment for amplitude modulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amplifier operates in the linear region to reduce noise and interference, then signal quality is improved, but power consumption increases because the amplifier is always on

Engineering Contradiction:

Improvesignal qualityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by using pulse width modulation (PWM) to generate periodic pulse signals that switch the amplifier between on and off states. The amplifier operates in saturation mode during active pulses and remains off during inactive periods, creating a periodic operation pattern that reduces average power consumption while maintaining signal quality through controlled switching

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent employs parameter changes by varying the pulse width (duration) of the digital signal to control the amplifier's operation. By adjusting the pulse width parameter, the system optimizes the balance between signal quality and power consumption, allowing the amplifier to operate efficiently in saturation mode during active periods while minimizing power consumption during inactive periods

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the amplifier operates in the saturated region to reduce power consumption, then power efficiency is improved, but signal quality deteriorates due to non-linear operation and harmonics

Engineering Contradiction:

Improvepower efficiencyVSAvoidsignal quality

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses periodic pulse signals with controlled duty cycles to operate the amplifier in saturation mode. The periodic switching between on and off states allows the amplifier to spend minimal time in the non-linear saturation region, reducing harmonic generation while maintaining high power efficiency during active periods

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary action by pre-shaping the digital signal with specific pulse widths and patterns before amplification. This pre-conditioning of the signal ensures that the amplifier operates in saturation mode with minimized distortion and harmonics, improving signal quality while maintaining power efficiency

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If pulse width modulation is used to control amplifier operation, then power consumption is reduced, but device complexity increases due to additional modulation circuits

Engineering Contradiction:

Improvepower consumptionVSAvoidmodulation circuit complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent replaces complex analog modulation circuits with digital signal processing techniques. By using digital logic circuits to generate PWM signals and control the amplifier, the system achieves power consumption control with simpler, more integrated digital components rather than complex analog modulation hardware

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9503294B1Amplitude and phase shift keying modulation for saturated amplifier systems

Publication Date: 2016.11.22 NORTHROP GRUMMAN SYSTEMS CORP

AI summary

An amplitude and phase modulation circuit for modulating an M-ary digital signal having pulses onto a carrier wave for transmission by direct digital synthesis. The modulation circuit includes a digital source that generates a digital signal including pulses representing logical 1s and no pulses representing logical zeros, where a group of M pulses represents a constellation point to be transmitted. The modulation circuit further includes a phase control circuit that provides phase control and an amplitude control circuit that provides pulse width control for the constellation point to be transmitted. A saturated amplifier amplifies the phase and amplitude controlled digital signal and a filter integrates and averages the digital signal to remove noise from the signal so as to convert the digital signal to an analog signal, where the digital source operates to reduce the amplifier power consumption requirements.