Baseband Digital Pre-Distortion for CATV Amplifier Linearity
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Solution Overview
Problem
Power amplifiers in communication systems face challenges with limited linearity of output responses, which digital pre-distortion (DPD) aims to enhance, but existing implementations are costly and inefficient.
Innovation Solution
Implementing digital pre-distortion in a lower frequency domain, such as baseband or intermediate frequency, within digital communication circuits, which includes a baseband digital pre-distortion circuit, up-conversion circuitry, and feedback circuitry to generate and apply pre-distortion signals to power amplifiers, reducing hardware costs and DC power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital pre-distortion is implemented in radio frequency domain, then linearity of power amplifier output response is improved, but hardware cost and power consumption increase
Solution Approach 1:
The patent introduces an intermediate frequency domain as a mediator between baseband and radio frequency. The DPD processing is performed at this intermediate frequency, which requires lower processing power and hardware resources compared to full RF domain processing, while still achieving effective linearization of the power amplifier output response.
Solution Approach 2:
The patent changes the frequency parameter of the signal processing from radio frequency to a lower intermediate frequency or baseband domain. This parameter change reduces the computational complexity and hardware requirements for DPD implementation while maintaining the linearity improvement effect through appropriate frequency translation and processing.
2Reliability
If digital pre-distortion is implemented in radio frequency domain, then linearity of power amplifier output response is improved, but hardware cost increases
Solution Approach 1:
The patent introduces an intermediate frequency domain as a mediator between baseband and radio frequency. The DPD processing is performed at this intermediate frequency, which requires lower processing power and hardware resources compared to full RF domain processing, while still achieving effective linearization of the power amplifier output response.
Solution Approach 2:
The patent changes the frequency parameter of the signal processing from radio frequency to a lower intermediate frequency or baseband domain. This parameter change reduces the computational complexity and hardware requirements for DPD implementation while maintaining the linearity improvement effect through appropriate frequency translation and processing.
3Measurement precision
If digital pre-distortion is implemented in higher frequency domain, then processing accuracy is improved, but processing speed and efficiency decrease
Solution Approach 1:
The patent transitions the processing from the time domain at high frequency to the frequency domain at lower intermediate frequencies. This dimensional change in the processing space allows for more efficient algorithms that maintain accuracy while improving processing speed, as the lower frequencies require fewer computational operations for the same level of precision.
Data Source
AI summary
Described examples provide for digital communication circuits and systems that implement digital pre-distortion (DPD). In an example, a circuit includes a baseband DPD circuit, up-conversion circuitry, and feedback circuitry. The baseband DPD circuit comprises a baseband signal path and pre-distortion path. The pre-distortion path is configured to generate a pre-distortion signal based on the baseband signal. The baseband DPD circuit includes a first adder configured to add the baseband signal from the baseband signal path and the pre-distortion signal from the pre-distortion path to generate a pre-distorted baseband signal. The up-conversion circuitry is configured to convert the pre-distorted baseband signal to a radio frequency signal. The up-conversion circuitry is configured to be coupled to an input of a cable television (CATV) amplifier. The feedback circuitry comprises a DPD engine configured to determine a configuration of the pre-distortion path based on an output signal on the output of the CATV amplifier.