Digital Delta-Sigma Modulator with Adjustable Output Frequency Band
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Solution Overview
Problem
Fully-recursive delta-sigma digital-to-analog converters (DACs) are limited by their maximum output data rate, which restricts their performance and introduces spectral artifacts when attempting to parallelize or pipeline for higher output rates, making them impractical for many applications.
Innovation Solution
A digital delta-sigma modulator with non-recursive computation of residues and dynamically adjustable output frequency, allowing for increased output sample rates through parallelization and pipelining, while maintaining signal quality by pre-computing and storing waveforms for higher transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fully-recursive delta-sigma DAC is used, then feedback loop provides noise shaping, but maximum output data rate is limited
Solution Approach 1:
The patent segments the recursive feedback loop into separate functional blocks that can be independently computed and parallelized. By dividing the residue computation into non-recursive segments, the system achieves higher output data rates while maintaining noise shaping through distributed feedback paths.
Solution Approach 2:
The patent pre-computes waveform data and stores it in lookup tables before runtime. This preliminary action allows the system to retrieve pre-computed values during operation, significantly increasing output data rate without requiring complex real-time recursive computations.
2Productivity
If parallelization or pipelining is attempted for higher output rates, then productivity increases, but spectral artifacts are introduced
Solution Approach 1:
The patent introduces intermediary components including lookup tables and interpolation circuits that mediate between parallel computation paths. These intermediaries ensure that parallelized operations produce coherent output without introducing spectral artifacts, maintaining signal quality while achieving high output rates.
Solution Approach 2:
The patent implements dynamic adjustment of computation parameters and feedback timing to adapt to different operating conditions. This dynamic approach allows the system to maintain optimal signal quality across varying output rates by adjusting computational depth and feedback application timing.
3Productivity
If output sample rate is increased, then operational bandwidth or dynamic range improves, but computational complexity increases
Solution Approach 1:
The patent pre-computes and stores waveform data in lookup tables at lower computational rates. During high-speed operation, the system retrieves and interpolates from these pre-computed tables, achieving high output sample rates without proportionally increasing computational complexity.
Solution Approach 2:
The patent uses copied and reused computational patterns through interpolation circuits that generate high-rate output from lower-rate pre-computed data. This copying approach allows the system to achieve high output rates by replicating and timing-adjusting base computational patterns rather than performing full computations at the target rate.
Data Source
AI summary
A delta-sigma modulator (DSM) with non-recursive computation of delta-sigma residues comprising: an input port for receiving a digital input signal; a residue calculation circuit coupled to the input port for calculating delta-sigma residues non-recursively; a DSM output calculation circuit coupled to the output of the residue calculation circuit for generating an output of the DSM; and a second input port for receiving a control signal, wherein the control signal dynamically adjusts an output frequency band of the DSM.