Differential Integrator Calibration for Charge Pump Current Sensing
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Solution Overview
Problem
Existing electronic circuits face challenges in accurately monitoring and regulating current drawn from a power source, such as batteries, to prevent damage to capacitive charge pump systems and integrated circuits, requiring high accuracy in current comparison.
Innovation Solution
A gain calibration method and system within a charge pump that uses a differential integrator with coarse and fine trim adjustments to ensure accurate current sensing, employing a resistor for current sensing and a bandgap reference voltage conversion to achieve precise calibration over a range of current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a single calibration point is used, then calibration time is reduced, but accuracy over a range of current levels may be compromised
Solution Approach 1:
The patent changes the parameters of the differential integrator circuit by applying coarse trim to adjust the gain and fine trim to adjust the threshold voltage. This allows a single calibration point to be used while maintaining accuracy across a range of current levels, resolving the contradiction between calibration time and measurement precision.
2Measurement precision
If coarse trim and fine trim are both applied, then current measurement accuracy is improved, but circuit complexity increases
Solution Approach 1:
The calibration process is segmented into two distinct stages: coarse trim for gain adjustment and fine trim for threshold voltage adjustment. This segmentation allows each trim to address specific error sources independently, improving measurement precision while keeping the circuit implementation manageable through modular adjustment mechanisms.
Data Source
AI summary
An apparatus for calibrating a differential circuit that includes a differential integrator having an input, a gain, and an output connected to a comparator. The differential integrator output is chargeable to a threshold prior to an integration period. The differential integrator integrates the input during the integration period such that the differential integrator output goes toward zero from the threshold. The comparator detects the output of the differential integrator reaching zero. The apparatus includes a closed-loop gain trim circuit to perform a coarse calibration to adjust and set the gain of the differential integrator and a reference generator that generates the threshold to which the differential integrator output is pre-charged. The reference generator is trimmable during a fine calibration to adjust and set the threshold to correct for residual gain error in the differential circuit remaining after the coarse calibration is performed.