Signal Converter Power-State Switching for Harmonic Suppression
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Solution Overview
Problem
Existing sigma-delta modulators introduce significant distortion during analog-to-digital conversions due to mismatch in digital-to-analog converters, leading to noise and spurious signals that degrade circuit performance.
Innovation Solution
A signal converter system that includes two resistor ladders and a controller to generate control signals that flip the power supply states of the converters, synchronizing these changes with selection states to suppress harmonics and distortion, thereby improving the signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If data-weighted-averaging (DWA) algorithms are used to perform noise shaping, then noise is reduced, but the algorithm introduces additional noise and complexity
Solution Approach 1:
The patent extracts and eliminates the source of distortion by using multiple DACs with complementary residue signals. Instead of trying to shape or filter the noise after it is generated, the system removes the distortion at its source by canceling out the mismatch errors through signal subtraction, thereby avoiding the need for complex DWA algorithms.
Solution Approach 2:
The patent introduces an intermediary signal processing path where the residue signals from multiple DACs are combined and processed before being fed back to the modulator. This intermediary path allows for distortion cancellation without requiring complex noise shaping algorithms in the main signal path.
2Manufacturing precision
If an excessive number of extra switches, amplifiers, and/or other circuit components are used, then matching is improved, but noise increases, power consumption increases, and matching requirements are not eliminated
Solution Approach 1:
The patent segments the single DAC function into multiple parallel DACs, each handling a portion of the signal. By dividing the conversion task among multiple simpler DACs and combining their outputs with appropriate weighting, the system achieves better overall matching precision without requiring each individual DAC to be highly precise, thereby reducing noise from excessive component usage.
Solution Approach 2:
The patent merges multiple DAC outputs through a combining network that weights and sums the residue signals. This merging process allows the system to achieve high precision by combining several moderate-precision DACs rather than using a single high-precision DAC with many complex components, thereby reducing noise and power consumption.
3Object-affected harmful factors
If mismatch occurs in the digital-to-analog converter, then harmonics and spurious signals are introduced, but increasing converter complexity to reduce mismatch increases power consumption and noise
Solution Approach 1:
The patent converts the harmful effect of DAC mismatch into a beneficial cancellation mechanism. By intentionally creating complementary residue signals from multiple DACs that are combined in a specific way, the system transforms the mismatch errors into canceling signals, where the harmonics and spurious signals from one DAC are canceled by the corresponding errors from another DAC, reducing total distortion without increasing power consumption.
4Manufacturing precision
If noise shaping is performed to reduce distortion, then signal quality improves, but additional noise is introduced by the shaping algorithm
Solution Approach 1:
The patent performs preliminary distortion cancellation by combining and weighting the residue signals from multiple DACs before they are fed back to the modulator. This preliminary action removes the distortion components early in the signal path, preventing them from propagating through the system and eliminating the need for subsequent noise shaping operations that would introduce additional noise.
Data Source
AI summary
A signal converter includes a first converter, a second converter, a signal generator, and a controller. The first converter generates a first analog signal from a digital signal, and the second converter generates a second analog signal from the digital signal. The signal generator outputs a converted analog signal based on the first analog signal and the second analog signal. The controller generates one or more control signals to change a power supply state of at least one of the first converter and the second converter. The change in power supply state suppress even order harmonics.