Delta-Sigma Modulator Feedback Switching for Excess Loop Delay
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Solution Overview
Problem
Continuous time Delta Sigma Modulators (CTDSMs) face stability and signal-to-noise ratio degradation due to excess loop delay, which is a challenge for high-speed applications requiring high sampling rates.
Innovation Solution
A delta sigma modulator architecture that includes a loop filter, comparators, and a reference select logic unit with pre-computed reference voltages, which are activated by switching signals to provide fast feedback and increase sampling frequency, thereby reducing excess loop delay and enhancing resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If continuous time delta sigma modulator is used for high speed applications, then sampling rate is increased, but excess loop delay degrades stability and signal to noise ratio
Solution Approach 1:
The patent pre-calculates and stores reference voltages in a lookup table before operation. During high-speed conversion, the system directly retrieves pre-computed reference values instead of calculating them in real-time, eliminating computational delay and maintaining stability at high sampling rates
Solution Approach 2:
The system dynamically selects reference voltages from the lookup table based on the current digital output state. This dynamic adaptation allows the modulator to compensate for excess loop delay effects in real-time while operating at high sampling rates, maintaining both speed and stability
2Speed
If continuous time delta sigma modulator is used for high speed applications, then sampling rate is increased, but excess loop delay degrades signal to noise ratio
Solution Approach 1:
Reference voltages are pre-computed and stored to account for excess loop delay effects. This preliminary action ensures that the correct compensation values are immediately available during high-speed operation, maintaining signal to noise ratio despite increased sampling rate
Solution Approach 2:
The system uses feedback from the digital output to select appropriate pre-computed reference voltages. This feedback mechanism ensures that the reference values used for comparison account for the actual loop delay conditions, preserving measurement precision at high sampling rates
Data Source
AI summary
A technique for excess loop delay compensation in delta sigma modulator. The delta sigma modulator includes a loop filter. The loop filter receives an analog input signal and an output of a digital to analog converter. A comparator receives an output of the loop filter and generates a digital output signal. A reference select logic unit receives the digital output signal as a feedback and generates one or more switching signals. One or more switches are coupled to the comparator and each switch receives a pre-computed reference voltage. The one or more switches are activated by the one or more switching signals in response to the digital output signal.