Delta-Sigma Voltage Regulation With Feedforward for Low-Ripple Stability
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Solution Overview
Problem
Conventional voltage regulators, such as LDOs, face challenges in efficient and reliable operation due to complex stability analysis, high ripple, poor bandwidth, and scalability issues, particularly in low voltage applications.
Innovation Solution
A voltage regulator device incorporating a digital modulation device with a delta-sigma modulator, quantizer, and feedforward path, which digitally modulates the feedback signal and feeds it forward to control the power device, reducing quantization noise and improving stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional analog LDO is used, then voltage regulation is achieved, but stability analysis becomes complex due to varying pole and zero locations
Solution Approach 1:
The patent replaces the conventional analog error amplifier with a digital modulation device comprising a delta-sigma modulator and quantizer. This substitution transforms the continuous analog control signal into a pulsed digital signal, eliminating the need for complex stability analysis of analog poles and zeros while maintaining voltage regulation functionality.
Solution Approach 2:
The invention changes the control signal representation from analog voltage levels to digital pulse density modulation. The delta-sigma modulator converts the error signal into a high-frequency pulse stream where the density of pulses represents the error magnitude, fundamentally changing the parameter space and simplifying stability characteristics.
2Extent of automation
If conventional digital LDO with ADC and shift register is used, then digital control is achieved, but output ripple increases
Solution Approach 1:
The patent employs periodic high-frequency pulsing through the delta-sigma modulator to control the power device. This periodic action with frequency far exceeding the bandwidth of interest effectively pushes quantization noise and ripple to higher frequencies where they can be filtered by the output capacitor, reducing visible output ripple.
Solution Approach 2:
The delta-sigma modulator acts as an intermediary between the digital comparator output and the power device control. It processes the digital error signal through noise shaping and pulse density modulation, mediating the control signal to minimize harmful ripple while maintaining digital control benefits.
3Extent of automation
If conventional digital LDO with shift register is used, then digital control is achieved, but bandwidth becomes poor
Solution Approach 1:
The patent removes the shift register delay by directly connecting the comparator output to the delta-sigma modulator input. This preliminary action eliminates unnecessary processing stages and delays, allowing the regulation loop to respond more quickly to load changes and improving bandwidth.
Solution Approach 2:
The invention replaces the conventional digital control architecture with ADC-shift register-DAC with a direct digital modulation approach. The delta-sigma modulator processes the error signal without intermediate sampling and holding stages, substituting the traditional multi-stage digital control path with a more direct digital modulation scheme that improves response speed.
4Use of energy by moving object
If conventional class D LDO is used, then high efficiency is achieved, but process dependence increases
Solution Approach 1:
The patent creates a universal voltage regulator architecture that functions across different manufacturing processes and voltage conditions. The digital delta-sigma modulator and quantizer provide process-insensitive control that adapts to varying process parameters, making the regulator versatile across different technology nodes and process variations.
Data Source
AI summary
It is described a voltage regulator device (100), comprising:i) a power device (150), configured to receive an input signal (151) and to produce a corresponding output signal (152);ii) a comparator device (110), coupled via a feedback path (140) to the power device (150), and configured to receive the output signal (152) as a feedback signal (141), and to produce a compared feedback signal (112); andiii) a digital modulation device (120), arranged between the comparator device (110) and the power device (150), and configured to digitally modulate the compared feedback signal (112), and to provide the digitally modulated signal (121) to the power device (150), wherein the digital modulation device (120) comprises:iiia) a delta-sigma (122),iiib) a quantizer (124), andiiic) a feedforward path (128), configured to feedforward the compared feedback signal (112) beyond the delta-sigma (122).