Sigma-Delta Load Supply Control for Voltage Compensation
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Solution Overview
Problem
Existing control apparatuses for load supply devices are complex and costly in terms of semiconductor chip area due to the need for large digital resources to compensate for supply voltage variations, particularly in digital multipliers and look-up tables used for pulse-width modulation.
Innovation Solution
A control apparatus utilizing a sigma-delta device with a feedback circuit that digitalizes the supply voltage and produces a pulse-density modulation signal, where the digital output is proportional to the inverse of the digitalized supply voltage, minimizing circuit complexity and chip area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a look-up table or real-time inversion circuit is used to compensate for supply voltage variations, then the compensation accuracy is improved, but the device complexity and silicon area occupation increase significantly
Solution Approach 1:
The patent replaces complex digital inversion circuits or look-up tables with an analog-based solution. A capacitor is charged through a resistor with resistance inversely proportional to the supply voltage, and the charging time (measured by a counter) provides the compensated value. This substitutes complex digital logic with simple analog RC timing, dramatically reducing silicon area and circuit complexity while maintaining compensation accuracy.
Solution Approach 2:
The patent introduces an intermediary measurement process: instead of directly computing the inverse of the supply voltage digitally, it uses the charging time of a capacitor as an intermediary physical quantity that naturally represents the inverse relationship. The counter measures this time, and the resulting digital value is already compensated, eliminating the need for complex inversion logic.
2Reliability
If digital multipliers and look-up tables are implemented to compensate for supply voltage variations, then the compensation performance is improved, but the semiconductor chip area increases
Solution Approach 1:
The patent replaces area-intensive digital multipliers and look-up tables with a compact analog RC charging circuit and a simple counter. The physical charging process of the capacitor through the resistor naturally performs the multiplication/division operation needed for compensation, requiring minimal silicon area compared to digital implementations.
Solution Approach 2:
The RC circuit automatically performs the compensation function based on the supply voltage itself. The charging time inherently reflects the inverse relationship with supply voltage, and the counter automatically captures this information. No additional complex control logic or large memory structures are needed—the system uses the supply voltage to compensate for itself through physical laws.
Data Source
AI summary
A control apparatus for a supply device of a load, the supply device is of switching type and connected between a supply voltage and a reference voltage, the apparatus including a sigma-delta device having an input terminal at which is present a first digital signal and adapted to provide a pulse-density modulation signal at the output terminal; the sigma-delta device including a feedback circuit capable of sending to the input terminal of the sigma-delta device a second digital signal whose value depends on the value of the output signal, and the apparatus including a device capable of digitalizing the supply voltage and of providing a further digital signal. The feedback circuit includes a terminal capable of receiving the further digital signal, and the sigma-delta device having a gain such that the output digital signal is proportional to the inverse of the further digital signal.