ADC Compensation Network for Voltage Metering Error Reduction
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Solution Overview
Problem
In battery-powered electronic devices, the Coulomb counter in power management integrated circuits faces challenges in capturing fast input transients while maintaining low current consumption, leading to a differential input voltage error due to high value input resistances, which affects the accuracy of battery state-of-charge estimation.
Innovation Solution
A voltage metering module with an analogue to digital converter (ADC) component that includes a compensation network to reduce input current errors, using a switching arrangement to couple the input to either the voltage signal or a reference voltage signal, and an integrator to generate an integrated sampled voltage signal, thereby compensating for input current components and reducing voltage errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high value input resistances are used in the RC filter to compensate for limited capacitance size, then the input signal bandwidth requirement is met, but the differential input voltage error increases significantly
Solution Approach 1:
A compensation network is introduced as an intermediary element between the RC filter and the ADC converter. This network generates a compensating signal that counteracts the differential input voltage error caused by the high value input resistances, allowing the system to maintain both the required input signal bandwidth and measurement precision
Solution Approach 2:
The compensation network uses feedback from the ADC converter's input current information to generate a compensating signal. This feedback mechanism allows the system to dynamically adjust and cancel out the voltage errors introduced by the high value resistances in the RC filter
2Use of energy by moving object
If the sampling frequency is kept low to maintain low current consumption in the Coulomb counter, then energy efficiency is improved, but the ability to capture fast input transients is reduced
Solution Approach 1:
The RC filter with its memory effect performs preliminary action by smoothing and integrating the input signal before it reaches the low-frequency ADC converter. This preliminary filtering action allows the system to capture fast transients through the filter's inherent temporal integration while the ADC operates at low frequency to conserve energy
Solution Approach 2:
The compensation network acts as an intermediary that bridges the gap between the low sampling frequency and the need to capture fast transients. By compensating for the input current effects, it allows accurate representation of transient signals even when sampled at low frequencies
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces input voltage errors and maintains accurate battery state-of-charge estimation by compensating for input current components, enhancing the accuracy of battery capacity prediction in next-generation devices.
Implementation Method 1
The voltage (Vsns_diff) across a sense resistor 110 is filtered using a single pole RC filter
Implementation Method 2
an integrator to generate an integrated sampled voltage signal
Implementation Method 3
A compensation network is provided which is controllable to sample the voltage signal to generate a compensating signal
Data Source
AI summary
A voltage metering module for metering a voltage signal at least one analogue to digital converter (ADC) component arranged to receive at an input thereof a voltage signal and to generate a digital signal representative of the received voltage signal. The at least one ADC component includes at least one sampling network controllable to sample the received voltage signal for conversion to a digital signal representative of the received voltage signal and at least one compensation network operably coupled in parallel with the sampling network and controllable to sample the received voltage signal such that an input current of the compensation network at least partially compensates for a component of an input current of the sampling network.