Continuous-Time Delta Sigma Modulator With Embedded CVC
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Solution Overview
Problem
Conventional delta sigma modulators face challenges in achieving high resolution while maintaining power efficiency, as they often suffer from noise folding and increased thermal noise, and require additional capacitance-to-voltage converters that increase power consumption.
Innovation Solution
A continuous-time delta sigma modulator with an embedded capacitance-to-voltage converter and a voltage-controlled oscillator-based integrator, which reduces thermal noise and power consumption by integrating the CVC within the sigma-delta loop and using multi-bit quantization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete-time delta sigma modulators are used to achieve high resolution, then measurement precision is improved, but thermal noise increases due to noise folding
Solution Approach 1:
The patent inverts the conventional discrete-time approach by implementing a continuous-time delta sigma modulator. This inversion eliminates the sampling operation that causes noise folding, thereby reducing thermal noise while maintaining high resolution through continuous signal processing throughout the modulator circuit.
Solution Approach 2:
The patent changes the fundamental operating parameter from discrete-time sampling to continuous-time processing. By transitioning the modulator from discrete to continuous operation, the noise characteristics are fundamentally altered, eliminating the noise folding effect inherent in sampled systems while preserving measurement precision.
2Measurement precision
If discrete-time delta sigma modulators with sensing capacitors are used, then measurement precision is improved, but power consumption increases due to charging and discharging of large capacitors
Solution Approach 1:
The patent extracts the large sensing capacitors from the continuous-time modulator circuit, eliminating the need to charge and discharge these large capacitors at the sampling frequency. This extraction removes the primary source of high power consumption while retaining the resolution benefits through alternative circuit implementation.
Solution Approach 2:
The patent changes the operational mode from discrete-time with periodic capacitor charging/discharging to continuous-time with steady-state operation. This parameter change eliminates the high-frequency switching losses associated with charging and discharging large sensing capacitors, significantly reducing power consumption.
3Measurement precision
If additional capacitance-to-voltage converters are added to achieve high resolution, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent merges the capacitance-to-voltage conversion function directly into the delta sigma modulator circuit itself, eliminating the need for separate external CVC components. This integration achieves high resolution measurement precision while reducing overall device complexity by combining multiple functions into a unified circuit architecture.
Solution Approach 2:
The patent implements a multi-functional modulator circuit that simultaneously performs capacitance sensing, voltage conversion, and delta sigma modulation within a single integrated structure. This universal circuit design eliminates the need for separate dedicated CVC components, reducing device complexity while maintaining high measurement precision.
Data Source
AI summary
Various embodiments may provide a delta sigma modulator for generating a digital output voltage. The delta sigma modulator may include a capacitance-to-voltage converter for converting a sensed continuous-in-time applied capacitance signal to a delta analog output voltage signal. The modulator may also include an integrator circuit arrangement configured to generate an analog output voltage signal based on the delta analog output voltage signal. The modulator may additionally include a quantizer circuit arrangement configured to generate the digital output signal based on the analog output voltage signal. The modulator may further include a voltage digital-to-analog converter configured to generate the analog charging voltage based on the digital output signal, thereby generating the delta analog output voltage signal based on the digital output signal.