Self-Referred Time Measurement for ADC Aperture Noise Suppression
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Solution Overview
Problem
Conventional analog-to-digital converters face challenges in isolating and suppressing clock jitter, particularly at high frequencies, as existing techniques like delta-sigma based sampling are limited to low input bandwidths and require oversampling, making them impractical for high-resolution, high-speed converters.
Innovation Solution
A system architecture that uses self-referred time measurements to estimate and subtract aperture noise, comprising a clock generator, delay element, time subtractor, time-to-digital converter, filter, digital subtractor, integrator, and multiplier to generate an output signal independent of jitter, effectively suppressing aperture noise associated with Nyquist ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If delta-sigma based sampling techniques are used to suppress aperture noise, then aperture noise suppression is improved, but input bandwidth is limited to low frequencies
Solution Approach 1:
The system separates the aperture noise measurement path from the signal conversion path. A dedicated measurement path uses a delay element and time subtractor to measure clock jitter, while the main path performs Nyquist sampling. This segmentation allows independent optimization of noise measurement without limiting signal bandwidth.
Solution Approach 2:
The patent introduces a time-to-digital converter (TDC) as an intermediary device that converts time differences (caused by clock jitter) into digital values. This TDC acts as a mediator between the analog clock signal and the digital processing domain, enabling precise jitter measurement without affecting the main signal path bandwidth.
2Object-affected harmful factors
If oversampling is used in delta-sigma based sampling, then aperture noise suppression is improved, but the number of RC time constants required increases
Solution Approach 1:
The system performs preliminary measurement of clock jitter using the delay element and time subtractor before the main conversion process. By measuring and compensating for aperture noise in advance, the system avoids the need for multiple RC time constants that would be required for post-conversion filtering in oversampling approaches.
Solution Approach 2:
The patent replaces the mechanical/physical RC time constant filtering mechanism with a digital signal processing approach. Instead of using multiple RC circuits for noise filtering, the system uses digital subtraction of measured jitter values, eliminating the need for numerous RC time constants and reducing hardware complexity.
3Productivity
If high-resolution, high-speed conversion is implemented, then conversion speed and resolution are improved, but aperture noise from clock jitter increases
Solution Approach 1:
The system implements a feedback mechanism where the measured clock jitter (aperture noise) is used to compensate for its effect on the conversion process. The measured jitter values are fed back into the system to correct the digital output, allowing high-speed conversion while maintaining precision by actively compensating for aperture noise effects.
Data Source
AI summary
A system and method for suppressing aperture noise resulting from clock jitter associated with a Nyquist analog-to-digital converter (ADC) using self-referred time measurements are provided. The system comprises of a clock, a delay element, a time subtractor, a time-to-digital converter, a filter element, a first digital subtractor, an integrator, a differentiator, and a multiplier. Each of the delay element, time subtractor, time-to-digital converter, filter element, first digital subtractor, integrator, and multiplier is electrically connected in parallel with the ADC, which allows the clock to generate a clock signal that advances into the system and the ADC in order to isolate and suppress the noise aperture associated with the ADC. As such, the architecture of the system is configured to isolate and suppress aperture noise resulting from clock jitter associated with an analog-to-digital converter (ADC) to allow the output signal of the system be independent of the aperture noise.