DAC Pre-Distortion and Calibration for High Dynamic Range
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Solution Overview
Problem
Traditional digital-to-analog converters (DACs) face a trade-off between achieving high bandwidth, dynamic range, and output power, often requiring amplification that compromises efficiency and thermal management, resulting in low output power levels unsuitable for applications like Active Electronically Scanned Arrays.
Innovation Solution
A system incorporating a digital pre-distortion circuit, a DAC core section, a power amplifier section, and a calibration circuit that pre-distorts digital signals to compensate for nonlinearities, allowing for high-efficiency amplification while maintaining dynamic range, with feedback mechanisms to adjust settings for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an amplifier is used to amplify the DAC output signal to reach required output power levels, then output power is improved, but dynamic range is compromised due to the efficiency trade-off
Solution Approach 1:
The patent applies digital pre-distortion to the input signal before it enters the DAC and amplifier chain. This preliminary action pre-compensates for the nonlinearities and compression effects that will occur during amplification, allowing the system to operate the amplifier in a more efficient regime while maintaining the required dynamic range and linearity in the final output signal.
2Manufacturing precision
If an amplifier is operated in a linear range to preserve dynamic range, then dynamic range is improved, but efficiency deteriorates resulting in high power consumption and thermal management complications
Solution Approach 1:
By applying pre-distortion beforehand, the system can operate the power amplifier in a higher efficiency regime (such as class AB or B) rather than requiring class A linear operation. The pre-distorted signal compensates for the amplifier's nonlinear characteristics, allowing efficient operation while maintaining the required dynamic range and signal fidelity.
3Use of energy by moving object
If an amplifier is used in the nonlinear regime with higher efficiency, then efficiency is improved and thermal issues are alleviated, but amplifier linearity is compromised resulting in reduced dynamic range of the output signal
Solution Approach 1:
The pre-distortion circuit intentionally distorts the input signal in advance to counteract the expected nonlinear distortion from the power amplifier. This allows the amplifier to operate in a more efficient nonlinear regime while the pre-applied distortion compensation ensures that the final output signal maintains the required linearity and dynamic range specifications.
4Manufacturing precision
If traditional DAC design emphasizes maximizing bandwidth and dynamic range, then bandwidth and dynamic range are improved, but output power remains low making it unsuitable for applications like AESAs
Solution Approach 1:
The patent integrates digital pre-distortion in the signal path before the DAC and amplifier stages. This preliminary processing enables the system to maintain high dynamic range and bandwidth characteristics while allowing subsequent amplification stages to boost the output power to levels suitable for high-power applications like Active Electronically Scanned Arrays without compromising the signal quality.
Data Source
AI summary
A system having: a digital pre-distortion circuit fed by a digital signal for distorting the digital signal; a digital to analog converter (DAC) core section coupled to an output of the calibration circuit for converting the distorted digital signal into a corresponding analog signal, the DAC core section performing the conversion in accordance with a control signal fed to the DAC core section; a power amplifier (PA) section coupled to an output of the DAC core section for amplifying power in the analog signal; and a calibration circuit coupled to the output of the power amplifier for producing, in response to the power in the power amplified analog signal, the control signal for the DAC core section.