RF Amplifier Supply Modulation with Delayed Envelope Prediction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cable television (CATV) networks face high power consumption due to the Class A mode of operation of RF amplifiers, which is inefficient as it requires significant power to accommodate peak to average deviations in signal power, leading to increased costs and energy expenditure.
Innovation Solution
The implementation of systems and methods that utilize digital forward path concepts, such as analog to digital (A2D) RF signal conversion, oversampling, compression coding, and optical on/off transmission, along with a delay-based prediction of signal envelope magnitude to modulate the power supply of RF gain blocks, reducing power consumption while maintaining signal fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Class A mode of operation is used for RF amplifiers, then signal fidelity is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies dynamics by transitioning from static Class A bias to dynamic bias modulation. The amplifier bias point is continuously adjusted according to the instantaneous signal envelope detected from the RF signal, allowing the amplifier to operate at optimal efficiency points while maintaining signal fidelity. This dynamic adaptation resolves the contradiction by making power consumption variable rather than fixed.
Solution Approach 2:
The patent changes the bias parameter dynamically based on signal characteristics. By detecting the signal envelope and using it to modulate the bias point, the system adapts the amplifier's operating parameters in real-time. This parameter change allows the amplifier to maintain high fidelity when needed while reducing power consumption during low-signal conditions.
2Measurement precision
If output RF rms amplitude is limited to 25% of output rail-to-rail range, then signal fidelity is maintained, but power consumption increases
Solution Approach 1:
The patent makes the output amplitude dynamic rather than static. Instead of permanently limiting the output to 25% of rail-to-rail range, the system dynamically adjusts the bias and output levels based on the instantaneous signal envelope. This allows the amplifier to utilize the full dynamic range when needed while maintaining fidelity, thereby reducing unnecessary power consumption.
Solution Approach 2:
The patent changes the output amplitude parameter dynamically based on signal conditions. By using envelope detection and bias modulation, the system adapts the output level to match the actual signal requirements, avoiding the permanent 25% limitation and its associated power waste while preserving signal fidelity.
3Use of energy by moving object
If power supply is modulated based on signal envelope, then power consumption is reduced, but amplifier operation complexity increases
Solution Approach 1:
The patent introduces an intermediary envelope detector that extracts signal amplitude information and uses it to control the bias modulation. This intermediary component simplifies the control architecture by separating the envelope detection function from the power modulation function, making the overall system more manageable despite the added complexity of dynamic operation.
Solution Approach 2:
The patent implements feedback by using the detected signal envelope to continuously adjust the amplifier bias. This feedback mechanism automates the power optimization process, reducing the need for complex manual control while achieving dynamic power consumption reduction based on actual signal conditions.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A device is disclosed for modulating an amplifier power supply to attain amplified RF output power with lower power dissipation. The signal to be amplified is delayed (320), and during the delay the signal envelope is used to generate an auxiliary signal which drives the power supply (370) of the gain block.