Digital Amplifier Modulator Using Multi-Pulse Amplitude Encoding
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Solution Overview
Problem
Digital amplifiers face challenges in achieving high output power with good energy efficiency and high bandwidth at high frequencies due to limitations in transistor frequency reserves, and existing modulation methods like EDSM and BPDSM are inefficient, leading to decharging and charging losses.
Innovation Solution
A modulator with a pulse shaper and control unit that encodes input signal amplitude into bit patterns, allowing for adaptable bit patterning and amplitude value representation, optimizing the bit stream for digital amplifiers by selecting control commands based on amplitude values and storing phase corrections, enabling improved efficiency and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If EDSM (Envelope Delta Sigma Modulation) is used to generate a binary signal for digital amplifiers, then the amplifier can operate with high efficiency, but the output amplitude cannot be fine-tuned and the linearity is poor
Solution Approach 1:
The invention segments the single binary pulse into multiple discrete pulses within one carrier period. Instead of using one pulse to represent the amplitude, multiple pulses (e.g., 3 pulses) are used, where each pulse has a fixed width but their combined duration encodes the amplitude value. This segmentation allows fine-tuning of the output amplitude while maintaining the high efficiency of digital amplification.
2Productivity
If BPDSM (Band Pass Delta Sigma Modulation) is used to modulate the RF signal, then the signal can be converted to a digital bit stream, but oversampling increases the number of switching operations causing decharging and charging losses
Solution Approach 1:
The invention adopts periodic action by confining all pulse operations within a single carrier period rather than using continuous oversampling. The modulator generates multiple discrete pulses within one carrier cycle, synchronized to the carrier frequency. This periodic approach maintains high signal conversion capability while dramatically reducing the number of switching operations compared to BPDSM, thereby minimizing decharging and charging losses in the amplifier.
3Measurement precision
If multiple pulses are used to represent amplitude values, then the output signal fidelity is improved, but the bit pattern complexity and device complexity increase
Solution Approach 1:
The invention changes the parameter representation from variable pulse width to variable pulse count. Instead of adjusting the width of individual pulses to encode amplitude, the system uses a fixed number of discrete pulses where the amplitude is encoded by which specific pulses are active within the carrier period. This parameter change simplifies the device complexity while maintaining high signal fidelity, as it avoids complex width modulation circuits.
Data Source
AI summary
The present disclosure relates to a modulator for a digital amplifier and a device comprising such a modulator and a digital amplifier.The modulator includes a pulse shaper and a control unit for controlling the pulse shaper to convert an input signal into a bit stream configured for a digital amplifier which encodes an amplitude value per clock of a carrier signal. The pulse shaper can represent a respective amplitude value of the input signal with different bit patterns. The control unit includes an assignment of the control commands to associated amplitude values resulting from amplification of the associated bit patterns with the digital amplifier is stored or at least is provided in that the control unit selects a control command per clock by means of the assignment and the amplitude value of the input signal and drives the pulse shaper accordingly.